The control tube that is used to compare to test broths 1, 2, and 3 in order to evaluate the effectiveness of the germicide is the positive control tube.
This control tube contains bacteria that are not exposed to the germicide and serves as a reference for the growth and viability of the bacteria in the absence of the germicide.
By comparing the growth and viability of the bacteria in the positive control tube to the growth and viability of the bacteria in the test broths, researchers can determine the effectiveness of the germicide in killing or inhibiting the growth of the bacteria.
It is important to use a positive control tube in order to establish a baseline for comparison and ensure accurate and reliable results
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if the size of the zinc electrode were doubled, does the cell voltage increase, decrease or stay the same? justify your answer.
In changing the size of the zinc electrode would not impact the voltage of the cell.
If the size of the zinc electrode were doubled, the cell voltage would stay the same. This is because the voltage of a cell is dependent on the difference in potential between the two electrodes, not their size.
Doubling the size of the zinc electrode would not change the potential difference between the zinc and copper electrodes, therefore the cell voltage would remain constant.
The only factor that would affect the cell voltage would be a change in the concentration or temperature of the electrolyte solution or a change in the material or surface area of the copper electrode.
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as lactic acid accumulates, which compensatory mechanism is initially triggered to maintain acid-base balance?
When lactic acid accumulates, the compensatory mechanism initially triggered to maintain acid-base balance is the respiratory system. It increases the rate and depth of breathing to eliminate more carbon dioxide, which helps reduce acidity and restore pH balance in the body.
As lactic acid accumulates, the compensatory mechanism that is initially triggered to maintain acid-base balance is increased ventilation or hyperventilation. This is because the increased ventilation leads to a decrease in carbon dioxide (CO2) levels in the blood, which helps to offset the acidic effects of lactic acid accumulation. This is a temporary compensatory mechanism, however, as the body will eventually need to eliminate the excess lactic acid through other means such as metabolism and excretion.
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ammonia is a weak electrolyte. which of the following is true about the behavior of ammonia in water? question 11 options: ammonia is insoluble in water ammonia forms no ions when it dissolves in water ammonia ionizes completely in water ammonia ionizes only partially in water
Ammonia ionizes only partially in water. Option 4 is correct.
When ammonia dissolves in water, it reacts with water to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻), according to the equation: NH₃ + H₂O ⇌ NH₄⁺ + OH⁻. However, this reaction is reversible and only a small fraction of ammonia molecules ionize to form ions. As a result, ammonia is classified as a weak electrolyte, meaning that it only conducts electricity weakly in solution.
Weak electrolytes are characterized by their partial ionization in solution, and they have relatively low electrical conductivity compared to strong electrolytes, which ionize completely in solution. Hence Option 4 is correct.
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If 120 cm3 of oxygen gas is collected at 27 oC and 713.3 mm Hg pressure, what will the volume (in cm3) of the dry gas be at STP?
If 120 cm³ of oxygen gas is collected at 713.3 mm Hg pressure, the volume of the dry gas at STP is 0.102 cm³.
How do you calculate the volume of the dry gas to be at STP?To solve this problem, we will use the ideal gas law, which relates the pressure, volume, temperature, and number of moles of a gas:
PV = nRT
First, we need to convert the given conditions to the correct units. The temperature is already in Celsius, so we need to convert it to kelvins by adding 273.15:
T = 27 + 273.15 = 300.15 K
The pressure is given in millimeters of mercury (mm Hg), so we need to convert it to atmospheres (atm) to use in the ideal gas law. There are 760 mm Hg in 1 atm, so:
P = 713.3 mm Hg / 760 mm Hg/atm = 0.938 atm
Next, we can use the ideal gas law to find the number of moles of oxygen gas:
n = PV/RT = (0.938 atm)(120 cm³)/(0.08206 L·atm/(mol·K))(300.15 K) = 0.00454 mol
Finally, we can use the molar volume of a gas at STP (standard temperature and pressure) to find the volume of the dry gas at STP. At STP, the temperature is 273.15 K and the pressure is 1 atm. The molar volume of a gas at STP is 22.4 L/mol, so:
V = n(22.4 L/mol) = (0.00454 mol)(22.4 L/mol) = 0.102 cm³
Therefore, the volume of the dry gas at STP is 0.102 cm³.
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Mrs. Johnson is 44 years old. She has fluctuating weakness around her eyes, difficulty
chewing and swallowing. She is told she has an autoimmune disorder that has no
cure. These symptoms describe:
O myasthenia gravis
O Cumulative trauma disorders
O muscular distropy
O tetanus
Answer:
A
Explanation:
M.G has no cure. it's an autoimmune disease that affects communication between nervous and the muscles.
if he gas has an average kinetic energy of 6430 j/mol under certain conditions, what is the root mean square speed of f2 gas molecules under the same conditions?
The root mean square speed of F2 Gas molecules under the same conditions is approximately 582.19 m/s
Given: Average kinetic energy (E_k) = 6430 J/mol
Molar mass of F2 = 2 * Molar mass of F = 2 * 19 g/mol = 38 g/mol (since F has a molar mass of 19 g/mol)
First, let's convert the molar mass of F2 from grams to kilograms:
Molar mass of F2 = 38 g/mol * (1 kg/1000 g) = 0.038 kg/mol
Now, we can use the equation for the average kinetic energy to determine the root mean square speed (v_rms):
E_k = (3/2) * R * T = (1/2) * m * v_[tex]rms^{2}[/tex]
Where R is the universal gas constant (8.314 J/mol K) and T is the temperature in Kelvin.
Since we want to find v_rms, we can rearrange the equation as follows:
v_[tex]rms^{2}[/tex] = (2 * E_k) / m
Plugging in the given values:
v_[tex]rms^{2}[/tex] = (2 * 6430 J/mol) / 0.038 kg/mol = 338947.37[tex]m^{2}/ s^{2}[/tex]
Finally, we take the square root to find the root mean square speed: a
v_rms = √338947.37[tex]rms^{2}[/tex] = 582.19 m/s
So, the root mean square speed of F2 gas molecules under the same conditions is approximately 582.19 m/s.
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Why is cerium sulfate (Ce2(SO4)3) the only compound that experiences a dip in solubility as temperature increases?
Answer: Because its dissolution is exothermic
Explanation:
Which of the following is evidence for a chemical reaction?(a) Dropping sodium metal into water gives a yellow flame.(b) Dropping iron metal into acid produces gas bubbles.
Both options (a) and (b) are evidence for a chemical reaction.
In option (a), the yellow flame is an indication that a chemical reaction has occurred between the sodium metal and water, producing hydrogen gas and sodium hydroxide.
In option (b), the gas bubbles produced indicate that a chemical reaction has occurred between the iron metal and the acid, producing hydrogen gas and iron(II) ions. Based on the given options, evidence for a chemical reaction can be observed in both (a) and (b).
In (a), dropping sodium metal into water produces a yellow flame, indicating a chemical reaction as new substances are formed. In (b), dropping iron metal into acid produces gas bubbles, which also signifies a chemical reaction as a new product, in this case gas, is generated.
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6Na + Fez0g -> 3NazO + 2Fe
If you are provided 200g of sodium and 250 grams of iron(Ill) oxide, how much of excess reagent is left?
The amount of excess reagent that will remain would be 11.76 g.
Stoichiometric problemTo determine the excess reagent in the reaction, we need to first determine which reactant is limiting and which reactant is in excess.
The balanced chemical equation for the reaction is:
6Na + Fe2O3 -> 3Na2O + 2Fe
The molar mass of Na is 23 g/mol, and the molar mass of Fe2O3 is 159.69 g/mol (2 x 55.85 g/mol for Fe + 3 x 16 g/mol for O).
Using the given masses, we can calculate the number of moles of each reactant:
Number of moles of Na = 200 g / 23 g/mol = 8.70 molNumber of moles of Fe2O3 = 250 g / 159.69 g/mol = 1.57 molAccording to the balanced chemical equation, 6 moles of Na react with 1 mole of Fe2O3. Therefore, the number of moles of Na required to react with 1.57 mol of Fe2O3 is:
(1.57 mol Fe2O3) x (6 mol Na/1 mol Fe2O3) = 9.42 mol Na
Since we only have 8.70 mol of Na available, it is the limiting reagent. This means that Fe2O3 is in excess.
To determine the amount of excess Fe2O3, we need to calculate how much Fe2O3 is required to react with 8.70 mol of Na:
(8.70 mol Na) x (1 mol Fe2O3/6 mol Na) x (159.69 g/mol Fe2O3) = 238.24 g Fe2O3
Since we only have 250 g of Fe2O3, the amount of excess Fe2O3 is:
250 g - 238.24 g = 11.76 g
Therefore, the amount of excess Fe2O3 left after the reaction is 11.76 g.
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17) An ionic compound was dissolved in 250 mL of water and the temperature of the solution increased from 25°C to 42°C. a. Is the value for AH greater than zero or less than zero. Justify your answer. b. Would you expect that the AH value has a large or a small magnitude? Justify your answer. c. Is the value for AG greater than zero or less than zero. Justify your answer.
When an ionic compound was dissolved in 250 mL of water and the temperature of the solution increased from 25°C to 42°C, the value of ΔH is lesser than zero and has a small magnitude and the value of ΔG is also lesser than zero.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process represents a physical change known as dissociation.
In this there is increase in temperature which means that heat energy is released which makes the dissolution exothermic and thus it has ΔH negative. Since the reaction is feasible, the ΔG will be less than zero.
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a solution containing 20.0 g of an unknown non-electrolyte liquid and 110.0 g water has a freezing point of -1.32 °c. given kf = 1.86°c/m for water, the molar mass of the unknown liquid is ____g/mol.
The molar mass of the unknown non-electrolyte liquid is given as
256 g/mol, option A.
The ratio between the mass and the amount of substance (measured in moles) of any sample of a chemical compound is known as the molar mass (M) in chemistry. The molar mass of a material is a bulk attribute rather than a molecular one.
ΔTemp.f = i x Kf x b
where,
ΔTemp.f = the freezing-point depression;
i = the Van't Hoff factor
Kf = the cryoscopic constant of the solvent;
b = the molality of the solution.
Solving for the molality, b = ΔTemp.f/( i * Kf)= 1.32/(1*1.86)
= 0.71 mol/kg
Converting from mol/kg to mol/g,0.71 mol/kg * 1kg/1000g
= 0.00071 mol/g.
Mass of solvent = 110gNumber of moles = mass * molality
= 0.00071 * 110
= 0.078 mol.
To calculate molar mass,Molar mass (g/mol) = mass/number of moles
Mass of solute (liquid) = 20g
Molar mass = 20/0.078
= 256.2 g/mol. ≈ 256 g/mol
Therefore, molar mass of the unknown liquid is 256.2 g/mol.
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Complete question:
A solution containing 20.0 g of an unknown non-electrolyte liquid and 110.0 g water has a freezing point of -1.32 °c. given kf = 1.86°c/m for water, the molar mass of the unknown liquid is ____g/mol.
A)256B) 69.0 C) 619 D) 78.1
The molar mass of the unknown liquid is 256.5 g/mol.To solve this problem, we can use the formula for calculating the freezing point depression: ΔTf = Kf·m·i
where ΔTf is the change in freezing point (in °C), Kf is the freezing point depression constant (in °C/m), m is the molality of the solution (in mol/kg), and i is the van't Hoff factor (which is 1 for non-electrolytes).
First, we need to calculate the molality of the solution:
molality = moles of solute / mass of solvent (in kg)
We know that the mass of the solvent (water) is 110.0 g, which is 0.1100 kg. To find the moles of solute (the unknown liquid), we need to divide its mass (20.0 g) by its molar mass (which we don't know yet). Let's call the molar mass "M":
moles of solute = 20.0 g / M
So, the molality is:
molality = (20.0 g / M) / 0.1100 kg
molality = (20.0 / M) / 0.1100 mol/kg
Now, we can plug this into the formula for freezing point depression:
ΔTf = Kf·m·i
-1.32 = 1.86·[(20.0 / M) / 0.1100]·1
Simplifying this equation, we get:
-1.32 = 1.86·(181.8 / M)
-1.32 = 338.628 / M
M = 338.628 / 1.32
M = 256.5 g/mol
Therefore, the molar mass of the unknown liquid is 256.5 g/mol.
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consider the reaction performed in the sn1 lab. what would be the effect on the rate of the reaction if 2-propanol (isopropanol) was used instead of 2-methyl-2-propanol (t-butanol) assuming only an sn1 reaction occurs? group of answer choices the rate of the reaction would decrease, because the secondary carbocation is more difficult to form. the rate of the reaction would increase, because the secondary carbocation is easier to form. there would be no difference in reaction rate. the reaction would not proceed at all.
The rate of the reaction is directly proportional to the stability of the carbocation intermediate, and any changes in the solvent will affect the rate of the reaction.
In an SN1 reaction, the rate-determining step is the formation of a carbocation intermediate. The stability of the carbocation intermediate affects the rate of the reaction.
In this case, if 2-propanol (isopropanol) was used instead of 2-methyl-2-propanol (t-butanol), the rate of the reaction would decrease. This is because the carbocation intermediate formed in 2-propanol is less stable compared to the one formed in t-butanol.
The carbocation intermediate formed in t-butanol is tertiary, which is more stable than the one formed in isopropanol, which is secondary. This means that the reaction will be slower in isopropanol due to the less stable carbocation intermediate.
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if a glass manufacturer has only a few of reducing pollutants, it will .
If a glass manufacturer has only a few costly ways of reducing pollutants, it will end up paying the pollution tax, option A.
A chemical or energy that is introduced into the environment and has negative consequences or reduces the usability of a resource is referred to as a pollutant or new entity. These can be either anthropogenic in origin (i.e., produced materials or results of biodegradation) or naturally formed (i.e., minerals or extracted chemicals like oil). When pollutants are present in sufficient quantities to have noticeable detrimental effects on the environment or public health, pollution results.
By altering the development rate of plant or animal species, or by affecting human amenities, comfort, health, or property values, a pollution may inflict long- or short-term damage.
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Complete question:
If a glass manufacturer has only a few ________________ of reducing pollutants, it will ____________________ .
A. costly ways; end up paying the pollution tax.
B. inexpensive ways; incur the pollution tax instead.
C. costly ways; do so to minimize its pollution taxes.
D. inexpensive ways; buy the most expensive technology.
Calculate the amount of copper obtained by the reaction. Was it the amount you expected? Explain.
The amount of copper obtained by the reaction depends on the amount of copper chloride reacted and the limiting reagent in the reaction.
Without information on the amounts of reactants used, it is not possible to calculate the amount of copper obtained by the reaction or compare it to the expected amount. However, if the reaction was carried out under controlled conditions and all reactants were used in the stoichiometric ratio, the amount of copper obtained should be the expected amount calculated based on the balanced chemical equation.
In order to calculate the expected amount of copper obtained, the amount of copper chloride reacted should be known, and the limiting reagent should be identified. The amount of copper obtained will be determined by the limiting reagent.
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The complete question is:
Calculate the amount of copper obtained by the reaction. Was it the amount you expected? Explain.
3CuCl2(aq) +2 Al (s) ----> 2AlCl3(aq) + 3Cu(s)
Boyle's Law: If it takes 0.0500L of oxygen gas kept in a cylinder under pressure to fill an evacuated 4.00L reaction vessel in which the pressure is 0.980atm. What was the initial pressure of the gas in the cylinder?
Name an ester that can be synthesized from propanol and methanoic acid?
Answer:
Propyl methanoate
Explanation:
The ester that can be synthesized from propanol and methanoic acid is propyl methanoate (also known as methyl propanoate or propyl formate). The reaction between propanol and methanoic acid, which is a carboxylic acid, is a classic example of an esterification reaction, which results in the formation of an ester and water.
consider the pictured structure of a dipeptide. dipeptide structure with labels a through d. the a label is at the end of the molecule with the positively charged nh3 group. the b label is placed by the bond between the carbonyl group and the amine. the c label is next to a carbon with shown single bonds to the carboxylate, a ch2oh, and the rest of the molecule. the d label is next to the carboxylate at the end of the molecule. what does each label on the structure represent?
The dipeptide structure with labels a through d represents the different functional groups and atoms present in the molecule.
Label a is located at the end of the molecule with the positively charged NH3 group, indicating the presence of an amino group. The b label is placed by the bond between the carbonyl group and the amine, indicating the presence of a peptide bond.
Label c is next to a carbon with shown single bonds to the carboxylate, a CH2OH, and the rest of the molecule, indicating the presence of a side chain. Finally, the d label is next to the carboxylate at the end of the molecule,
indicating the presence of a carboxylic acid functional group. Understanding the different functional groups and atoms present in the dipeptide structure is important in understanding its properties and behavior in chemical reactions and biological processes.
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The cloud droplets in a cloud are formed by water vapor molecules and: A) protons. B) ions. C) molecules of air. D) condensation nuclei.
Answer:
condensation nuclei
Explanation:
g standard conditions include a concentration of 1.0 m for soluble aqueous species, pure solids and liquids, and a partial pressure of 1 atm for gaseous species. group of answer choices true false previousnext
True. The standard conditions for measuring thermodynamic properties such as enthalpy, entropy, and Gibbs free energy are well-defined and standardized.
These conditions are used to compare and evaluate the relative stability and reactivity of different chemical species. The standard conditions for measuring these properties include a concentration of 1.0 m for soluble aqueous species, pure solids and liquids, and
a partial pressure of 1 atm for gaseous species. This means that the molar concentration of soluble aqueous species is set at 1.0 mol/L, and the pressure of gaseous species is set at 1 atm.
Pure solids and liquids are considered to have an activity of 1, which means that they do not affect the thermodynamic properties.
These conditions are used to determine the standard thermodynamic properties of chemical reactions, which are used to predict the direction and extent of chemical reactions.
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The atmospheric pressure on top of Mt. Everest (elevation 29,028) is 250. torr. Calculate the atmospheric pressure in mmHg and atm. Round each of your answers to 3 significant digits.
The atmospheric pressure on top of Mt. Everest is 250 mmHg and 0.328 atm, when rounded to 3 significant digits.
What is Pressure?Pressure is a force that is exerted over a surface area. It is the amount of force applied to an object per unit area. Pressure is typically expressed in units of force per unit of area, such as pounds per square inch (psi) or pascals (Pa). Pressure is an important factor in many areas of engineering, physics, chemistry, and biology.
Atmospheric pressure can be measured in torr (1 Torr = 1mmHg), atm (1 atm = 760mmHg) or in kPa (1 atm = 101.3kPa).
250 torr = 250 mmHg
250 mmHg / 760 mmHg = 0.328 atm
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a sample of br2(g) takes 14.0 min to effuse through a membrane. how long would it take the same number of moles of ar(g) to effuse through the same membrane?
A sample of [tex]Br_2[/tex](g) takes 14.0 min to diffuse out through a membrane. It would take 7 min for the same number of moles of Ar(g) to effuse through the same membrane.
According to Graham's Law of Diffusion, it is known that the rate of diffusion of a gas is proportional to the reciprocal of the square root of the molar mass of the gas. The rate of diffusion is recorded under the same pressure and temperature conditions.
It can be written as [tex]\frac{r_1}{r_2}[/tex] ∝ [tex]\sqrt\frac{m_2}{m_1}[/tex]
where [tex]r_1[/tex] is the rate of diffusion of one of the gas
[tex]r_2[/tex] is the rate of diffusion of the second gas
[tex]r_1[/tex] is the molar mass of one of the gas
[tex]m_2[/tex] is the molar mass of the second gas
According to the question,
[tex]\frac{14}{r_2}=\sqrt\frac{160}{40}\\\frac{14}{r_2}=\sqrt\frac{4}{1} \\\\r_2 = 14\sqrt{\frac{1}{4} } = 7[/tex]
Therefore the time taken for the diffusion of Ar (g) is 7 min
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It would take approximately 7.0 minutes for the same number of moles of Ar(g) to effuse through the same membrane.
Using Graham's law of effusion, we can compare the rates of effusion for Br2(g) and Ar(g). The formula for Graham's law is:
Rate₁ / Rate₂ = √(M₂ / M₁)
Here, Rate₁ and Rate₂ are the effusion rates of the two gases, and M₁ and M₂ are their molar masses. In this case, Br2(g) is gas 1 and Ar(g) is gas 2. The molar mass of Br2 is 159.8 g/mol, and the molar mass of Ar is 39.95 g/mol.
Since we know the time it takes for Br2 to effuse, we can write:
Time₁ / Time₂ = Rate₂ / Rate₁ = √(M₁ / M₂)
Plugging in the given time and molar masses:
14.0 min / Time₂ = √(159.8 g/mol / 39.95 g/mol)
Solving for Time₂:
Time₂ = 14.0 min * √(39.95 g/mol / 159.8 g/mol) ≈ 7.0 min
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PLEASE ANSWER ASAP
1. How many atoms are present in 8.500 mole of chlorine atoms?
2. Determine the mass (g) of 15.50 mole of oxygen.
3. Determine the number of moles of helium in 1.953 x 108 g of helium.
4. Calculate the number of atoms in 147.82 g of sulfur.
5. Determine the molar mass of Co.
6. Determine the formula mass of Ca3(PO4)2.
IT WOULD BE HELPFUL
1) 5.1167 x 10²⁴atoms of chlorine. 2) 248.00 g. 3) 4.8825 x 10⁷ moles of helium. 4) 2.7757 x 10²⁴ atoms of sulfur. 5) Molar mass of Co (cobalt) is 58.93 g/mol. 6) Formula mass = 310.18 g/mol.
What is meant by formula mass?Sum of the atomic masses of all the atoms in chemical formula is called formula mass
1.) Number of atoms = 8.500 moles x 6.022 x 10²³ atoms/mole = 5.1167 x 10²⁴ atoms of chlorine.
2.) Molar mass of oxygen is 16.00 g/mol. Therefore:
Mass of 15.50 moles of oxygen = 15.50 moles x 16.00 g/mol = 248.00 g.
3.) Molar mass of helium is 4.00 g/mol. Therefore, the number of moles of helium in 1.953 x 10⁸ g is:
Number of moles = 1.953 x 10⁸ g / 4.00 g/mol = 4.8825 x 10⁷ moles of helium.
4.) Molar mass of sulfur is 32.06 g/mol. Therefore, the number of moles of sulfur in 147.82 g is:
Number of moles = 147.82 g / 32.06 g/mol = 4.6084 moles of sulfur.
To find the number of atoms, we can use Avogadro's number again:
Number of atoms = 4.6084 moles x 6.022 x 10²³ atoms/mole = 2.7757 x 10²⁴ atoms of sulfur.
5.) Molar mass of Co (cobalt) is 58.93 g/mol.
6.) Ca₃(PO₄)₂ contains 3 calcium atoms, 2 phosphorus atoms, and 8 oxygen atoms.
Atomic masses of these elements are:
Calcium (Ca) = 40.08 g/mol
Phosphorus (P) = 30.97 g/mol
Oxygen (O) = 16.00 g/mol
Therefore, formula mass of Ca₃(PO₄)₂ is:
Formula mass = (3 x 40.08 g/mol) + (2 x 30.97 g/mol) + (8 x 16.00 g/mol)
= 120.24 g/mol + 61.94 g/mol + 128.00 g/mol
= 310.18 g/mol.
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what is molarity? match the items in the left column to the appropriate blanks in the sentences on the right.
Molarity (M) is a unit of concentration that expresses the amount of solute dissolved in a solution. It is defined as the number of moles of solute present per liter of solution (mol/L).
Molarity is commonly used in chemistry to express the concentration of a solute in a solution and is typically represented as moles of solute per liter of solution (mol/L or mol L^-1). Molarity is used to describe the concentration of a solution and is important in various calculations involving chemical reactions and solutions.
To calculate molarity, follow these steps:
1. Determine the number of moles of solute in the solution.
2. Measure the volume of the solution in liters.
3. Divide the moles of solute by the volume of the solution in liters.
Molarity = moles of solute/liters of solution
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Molarity is a unit of concentration in chemistry. It is defined as the number of moles of solute per liter of solution. In other words, it measures the amount of substance (in moles) dissolved in a given volume of solution (in liters). the left column contains "molarity," "moles," and "liters," and the sentences.
To match the items in the left column to the appropriate blanks in the sentences on the right, we can use the following:
- Molarity: a unit of concentration in chemistry
- Number of moles: the amount of substance dissolved in a solution
- Liter of solution: the volume in which the substance is dissolved
- Solvent: the substance in which the solute is dissolved
- Solute: the substance that is dissolved in a solvent to make a solution
So the sentences could be:
- Molarity is a unit of concentration in chemistry that measures the amount of substance (in moles) dissolved in a given volume of solution (in liters).
- The number of moles of solute per liter of solution is known as molarity.
- A liter of solution is the volume in which the solute is dissolved to make a solution with a certain molarity.
- A solvent is a substance in which a solute is dissolved to make a solution of a certain molarity.
- A solute is a substance that is dissolved in a solvent to make a solution of a certain molarity.
Hello! Molarity is a measure of the concentration of a solute in a solution, expressed as moles of solute per liter of solution. To match items in the left column to the appropriate blanks in the sentences on the right, follow these steps:
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Arrange the following events in the proper order in which they occur during an allergic response.
1 = Individual experiences symptoms
2 = Individual is sensitized to antigen
3 = IgE attaches to mast cells
4 = Antigen binds to IgE
Answer:
In order is 2, 3, 4, 1
Explanation:
It starts when you come into contact with a trigger that you inhale, swallow, or get on your skin. In response, your body starts to make a protein called IgE, which grabs onto the allergen. Then histamine and other chemicals get released into the blood.
what is the effect on the concentration of ammonia, hydroxide ion, and ammonium ion when the following are added to a basic buffer solution of equal concentrations of ammonia and ammonium nitrate:
Changes in the chemical environment of a basic buffer solution can cause shifts in the equilibrium between ammonia, hydroxide ion, and ammonium ion, leading to changes in their respective concentrations.
When a basic buffer solution of equal concentrations of ammonia and ammonium nitrate is subjected to changes in its chemical environment, the concentrations of ammonia, hydroxide ion, and ammonium ion will be affected as follows:
1) Addition of an acid: The acid reacts with the hydroxide ion present in the buffer solution to form water. This decreases the concentration of hydroxide ion and shifts the equilibrium towards the formation of more ammonia and ammonium ion, thus increasing their concentrations.
2)Addition of a base: The base reacts with the ammonium ion present in the buffer solution to form ammonia and water. This decreases the concentration of ammonium ion and shifts the equilibrium towards the formation of more hydroxide ion, thus increasing its concentration.
3)Dilution: Diluting the buffer solution with water decreases the concentrations of both ammonia and ammonium ion, but does not affect the concentration of hydroxide ion.
4)Addition of ammonium chloride: The ammonium chloride dissociates into ammonium ion and chloride ion in the buffer solution. The increase in ammonium ion concentration causes the equilibrium to shift towards the formation of more ammonia and hydroxide ion, thus increasing their concentrations.
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What is the concentration (in molality) of an aqueous solution of NaCl made by adding
4.56 g of NaCl to enough water to give 20.0 mL of solution. Assume the density of the
solution is 1.03 g/mL
Answer:
data given
mass of NaCl 4.56
dissolved volume 20ml(0.02l)
density of solution 1.03g/ml
Required molality
Explanation:
molarity=m/mr×v
where
m is mass
mr molar mass
v is volume
now,
molarity=4.56/58.5×0.02
molarity =3.9
: .molarity is 3.9mol/dm^3
According to molal concentration, the concentration (in molality) of an aqueous solution of NaCl is 0.0047 mole/kg.
What is molal concentration?Molal concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molal concentration is moles/kg.
The molal concentration depends on change in volume of the solution which is mainly due to thermal expansion. Molal concentration is calculated by the formula, molal concentration=mass/ molar mass ×1/mass of solvent in kg.
In terms of moles, it's formula is given as molal concentration= number of moles /mass of solvent in kg.
Substitution in formula gives the answer but first mass of solution is determined which is density×volume= 1.03×20=20.6 g , mass of solvent= 20.6-4.56=16.05, thus molal concentration=4.56/58.5×1/16.05=0.0047 moles/kg.
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the decrease in the second ionization energy of alkali metals going down the group, as shown in the table above, can be best attributed to a decrease in the coulombic force of attraction due to
The decrease in the second ionization energy of alkali metals going down the group is due to the increase in atomic radius.
As the atomic radius increases, the distance between the nucleus and the outermost electron increases, which reduces the coulombic force of attraction between the nucleus and the electron.
This reduced coulombic force of attraction reduces the energy required to remove the electron, thus resulting in a decrease in the ionization energy. Additionally, due to the increased number of electrons, the effective nuclear charge decreases, which further reduces the force of attraction between the nucleus and the electron, thus resulting in a further decrease in the ionization energy.
Therefore, the decrease in the second ionization energy of alkali metals going down the group can be attributed to a decrease in the coulombic force of attraction due to the increase in atomic radius and the decrease in the effective nuclear charge.
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given two orbitals as linear combinations of two atomic orbitals on carbon atom in ethene: where the hydrogen-like atomic orbitals are orthonormal. what is the value of the overlap integra
the overlap integral simplifies to:
S = c1c2 + d1d2d1d2.
To calculate the overlap integral between two linear combinations of atomic orbitals on a carbon atom in ethene, we first need to express the orbitals in terms of the hydrogen-like atomic orbitals. Let's assume that the two orbitals are denoted as ψ1 and ψ2, and can be expressed as linear combinations of the hydrogen-like atomic orbitals ϕ1 and ϕ2 as follows:
ψ1 = c1ϕ1 + d1ϕ2
ψ2 = c2ϕ1 + d2ϕ2
where c1, d1, c2, and d2 are constants.
The overlap integral between these two orbitals can be calculated using the following formula:
S = ∫ψ1ψ2*dτ
where dτ represents the infinitesimal volume element.
Substituting for ψ1 and ψ2, we get:
S = ∫(c1ϕ1 + d1ϕ2)(c2ϕ1 + d2ϕ2)*dτ
Expanding the product, we get:
S = c1c2∫ϕ1ϕ1*dτ + c1d2∫ϕ1ϕ2*dτ + d1c2∫ϕ2ϕ1*dτ + d1d2∫ϕ2ϕ2*dτ
Since the hydrogen-like atomic orbitals are orthonormal, the integral of ϕ1ϕ2 and ϕ2ϕ1 will be zero. Therefore, we can simplify the expression as follows:
S = c1c2∫ϕ1ϕ1*dτ + d1d2∫ϕ2ϕ2*dτ
Using the orthonormality of the hydrogen-like atomic orbitals, we know that the integral of ϕ1ϕ1 and ϕ2ϕ2 will both be equal to 1. Therefore, the overlap integral simplifies to:
S = c1c2 + d1d2d1d2.
In order to calculate the value of S, we need to know the values of the constants c1, d1, c2, and d2. These constants will depend on the specific linear combinations of atomic orbitals that we are considering. Without this information, we cannot calculate the value of the overlap integral.
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If two orbitals as linear combinations of two atomic orbitals on carbon atom in ethene, then value of the overlap integral [tex]S_{12} = \int{\phi_{1}}^{*}\phi_{2}d \tau[/tex], is equals to zero. So, option(b) is correct.
Orthonormal atomic orbitals are follow the following property:
[tex]\int{ m _i }* n_i d\tau = 1[/tex][tex]\int m_i^{*} n_j d\tau = 0[/tex]Now, we have provide that two orbitals are as a linear combinations of two atomic orbitals on carbon atom in ethene. [tex]\phi_{1 } = \frac{1}{ \sqrt{2} } ( {\psi_{2s }} + {\psi_{2p }}_{2})[/tex]
[tex]\phi_{2 } = \frac{1}{ \sqrt{2} } ( \psi_{2 s} - {\psi_{2p} }_{2})[/tex]
In the ethylene molecule, consists each carbon atom is bonded to two hydrogen atoms. Therefore, for the C-H, σ bond (sp²(C) - 1s(H)) in ethylene, the two sp² hybrid orbitals overlap with the 1s orbitals of the two hydrogen atoms. Let the hydrogen-like atomic orbitals, [tex]\psi_{2 s} and {\psi_{2p} }_{2}[/tex] are orthonormal to each other. So, the overlap integral [tex]S_{12} = \int{ \phi_{1}}^{*}\phi_{2}d \tau[/tex]
[tex] = \int \frac{1}{\sqrt{2}}( \psi_{2s} + {\psi_{2p} }_{2}) \frac{1}{\sqrt{2}}( \psi_{2s} - {\psi_{2p} }_{2})d \tau\\ [/tex]
[tex] = \frac{1}{\sqrt{2}}( \int \psi_{2s}\psi_{2s} d \tau + \int {\psi_{2p} }_{2}\psi_{2s} d \tau - \int \psi_{2s} {\psi_{2p}}_{2} d \tau - \int {\psi_{2p} }_{2} {\psi_{2p} }_{2} d \tau) \\ [/tex].
Using above formula, [tex]\psi_{2 s} [/tex] and [tex]{\psi_{2p} }_{2}[/tex] are orthonormal so, [tex]\int \psi_{2 s} {\psi_{2p} }_{2} d\tau = 0[/tex]. Also [tex]\psi_{2 s} [/tex] and [tex]\psi_{2 s}[/tex] are normalised so [tex]\int \psi_{2 s} \psi_{2 s} d\tau = 1[/tex]. Similarly [tex]\int {\psi_{2p} }_{2} {\psi_{2p} }_{2} d\tau = 1 [/tex].
Substitute all integral values in equation (1),
= 1 + 0 - 0 - 1
= 0
Hence, the required integral value is 0.
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Complete question:
given two orbitals as linear combinations of two atomic orbitals on carbon atom in ethene:
[tex]\phi_{1 } = \frac{1}{ \sqrt{2} } ( {\psi_{2s }} + {\psi_{2p }}_{2})[/tex]
[tex]\phi_{2 } = \frac{1}{ \sqrt{2} } ( \psi_{2 s} - {\psi_{2p} }_{2})[/tex]
where the hydrogen-like atomic orbitals are orthonormal. what is the value of the overlap integral,
[tex] S_{12} = \int \phi_{1} \times \phi_{2}dr[/tex]
a) 1
b) 0
c) 1.5
d) 2
which of the following statements is incorrect? select one: a. the entropy is larger when a disolved salt in a liquid is uniform or spread throughout the liquid than when it is highly concentration in a small portion of the liquid. b. an iron nail at 100oc has more entropy than the same nail at 250oc c. entropy decreases when a gas dissolves in a solvent, mainly because the dissolved molecules are confined to a smaller volume. d. adding heat to a substance always increases its entropy. e. entropy increases in going from the solid to the liquid to the gaseous state. f. when a solid dissolves in a liquid the entropy generally increases because the positional entropy increases. for example, dissolving a sugar cube in water. g. the kinetic energy of the particles in a sample increases as the temperature increases. the disorder increases as the motion of the particles increases. consequently, entropy increases as the temperature increases
The incorrect statement for entropy is the entropy is larger when a dissolved salt in a liquid is uniform or spread throughout the liquid than when it is highly concentration in a small portion of the liquid. The answer to this question is A..
Change in entropyThe entropy loss from ion binding and hydration decreases with increasing salt concentration, and at a certain temperature, the closure rate then increases noticeably with increasing ion concentration.The straightforward response is that water's entropy rises when salt dissolves in it, reducing the freezing point. A measure of disorder in a substance is called entropy, which is frequently used interchangeably with the word chaos.Entropy rises during the sublimation and evaporation processes, which transform a substance from a solid to a gas or a liquid to a gas. In a similar vein, entropy rises with the dissolution of a solid in water.A substance being divided into several pieces results in an increase in entropy. Due to the solute particles' separation from one another when a solution is generated, the dissolution process increases entropy.For more information on entropy kindly visit to
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What advice would you give to the company that wants to build a bridge in South America? Make sure to include whether there is anything the company should change about its design and materials. Give specific examples. Your answer should include at least five complete sentences.
When building a bridge in South America, it is important to consider the climate and terrain of the region. The company should research the area and use the most appropriate materials for the task.
What is materials?Materials are substances or resources that are used to create or make something else. Examples of materials include plastics, metals, fabrics, and paper. Materials are used in the manufacturing of products, such as food, clothing, furniture, and electronics. Materials can also be found in nature, including wood, stone, and minerals. They are also used in the construction of buildings, bridges, and other structures.
For example, they should use steel or reinforced concrete to build the bridge, as these materials are highly durable in wet, humid climates. Additionally, they should make sure to use corrosion-resistant fasteners and coatings to prevent rusting. The company should also consider the seismic activity in the region when designing the bridge, as earthquakes can cause significant structural damage. They should make sure to use seismic-resistant designs and materials, such as flexible joints, to help reduce the risk of damage. Lastly, the company should include guardrails and other safety features on the bridge, as it will be traversed by both pedestrians and vehicles.
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