Before the reaction of hydrogen peroxide, if a reagent had changed color immediately after being added to the sample, this would indicate the presence of a contaminant and the test would be invalid.
The above experiment is also knowns as a presumptive blood testing experiment in which if a contaminant is present, the test should be deemed invalid if a vivid blue or purple color appears after adding the TMB reagent but before adding the hydrogen peroxide; this is also frequently referred to as a "false positive" result.
Presumptive tests catalyze the oxidation of a chromogenic substance, which results in a color change, by reacting with the hemoglobin of all blood in humans and animals. If the test is positive, the material will be identified as potentially blood, though not necessarily human blood.
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Please help with the question!
Subtract the initial mass from final mass, i.e., vm.
The intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule is known as _________ ________.
The intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule is known as Hydrogen Bond.
An intermolecular force (IMF) known as a hydrogen bond is created when an electronegative atom with a single pair of electrons and a hydrogen atom connected to a strongly electronegative atom is in close proximity to one another. Between molecules, there are intermolecular forces (IMFs). Dispersion forces and regular dipole-dipole interactions are more examples. In general, hydrogen bonds are weaker than true covalent and ionic bonds but stronger than common dipole-dipole and dispersion forces.
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what absorbance did you record for spinach at 400 nm?6.25 points question 2what absorbance did you record for spinach at 420 nm?6.25 points question 3what absorbance did you record for spinach at 440 nm?
It was discovered that the photosynthetic pigment in spinach best absorbed light between the wavelengths of 400 and 450 nm as well as at 650 nm. Additionally, it was discovered that this green phototroph barely absorbed light at wavelengths about 550 nm.
What is Absorbance ?The logarithm of the ratio of incident to transmitted radiant power through a sample is known as absorbance. As an alternative, absorbance can be defined as "the negative logarithm of one minus absorptance, as measured on a homogeneous sample," for samples that scatter light.
The opposite of transmittance, or absorbance (A), indicates how much light the sample absorbed. Additionally known as "optical density." A logarithmic function of T is used to compute absorbance: A = log10 (1/T) = log10 (Io/I).The concentration of the molecule (C) and the sample's path length (L), which is typically equal to the cuvette's path length, combined make up the three factors that affect an absorbance value. The extinction coefficient () is the next factor.What is the absorbance of Spinach ?The disks will rise as a result of bubbles developing on their surface when the leaves create oxygen. The leaves eventually sink if the cup's light source is taken away.
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if 2.50g of the organic fuel was reacted with 2.50g of oxygen and 1.00g of water was actually produced, what is the percent yield of this reaction?
The percent yield would be 40% if 2.50g of the organic fuel was reacted with 2.50g of oxygen and 1.00g of water was produced.
How is the percent yield of an organic molecule determined?
The percentage yield is a figure generated to represent the discrepancy between an experiment's theoretical and actual yields. There are by-products and desired products while experimenting with various solutions or producing chemical solutions.To calculate the yield percentage: Multiply by 100 after dividing the actual yield obtained in the lab by the estimated theoretical yield.For instance, your percent yield would be as follows if you started with 100 grams of compound A and produced 80 grams of product B: 80% yield is equal to (80 grams B / 100 grams A) × 100.To learn more about percent yield, follow the link https://brainly.com/question/12704041
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It would be nice if someone could help me thank you so much.
Answer:
All answers are in the above periodic table
Explain why onions make you cry
if 5.01 moles of ti are mixed with 7.86 moles of cl2 and 2.47 moles of ticl4 are formed, what is the percent yield of this reaction? answer in percent to 3 significant figures.
Titanium is also utilized in the construction of portable computer housings and medical implants. Despite being the ninth most prevalent element in the crust of the Earth, titanium is relatively challenging to extract from its ores. Titanium-containing oxide minerals react with solid carbon and chlorine gas to produce titanium tetrachloride and carbrabon dioxide in the first step of the extraction process.
therefore,
5.01+7.86=12.87
12.87/2.47=19.1%
Yeild Percentage is 19.1%
Minerals are naturally occurring inorganic elements or compounds with an organized internal structure, a distinctive chemical composition, crystal shape, and physical characteristics. The yield percentage is 19.1%. Quartz, feldspar, mica, amphibole, olivine, titanium, and calcite are examples of common minerals.
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What is the best description of the relationship between emerging scientific ideas and open-mindedness?
Open-mindedness results from emerging scientific ideas.
Open-mindedness often leads to emerging scientific ideas.
Open-mindedness leads to critical evaluation of emerging scientific ideas.
Open-mindedness helps people understand that emerging scientific ideas are uncertain.
The best description of the relationship between emerging scientific ideas and open-mindedness is: Open-mindedness often leads to emerging scientific ideas.
The correct answer choice is option b
Why open-mindedness often leads to emerging scientific idea?It follows that scientific skills emanate faster when a scientist is very open-minded and open to corrections as well. The simple reason why our open-mindedness often results in emerging scientific ideas is simply because it is one of the major keys to investigating scientific problems.
In conclusion, it can be deduced when when we work with transparency, our scientific skills brings positive results.
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a 5.00 g sample of a compound containing only chlorine and oxygen contains 1.94 g of chlorine. what is the empirical formula of this compound?
The empirical formula of this compound is ClO₇.
If a 5.00 g sample of a compound containing only chlorine and oxygen contains 1.94 g of chlorine, then the mass of its oxygen is the difference between the mass of the sample and the mass of its chlorine.
mass compound = mass oxygen + mass chlorine
mass oxygen = mass compound - mass chlorine
mass oxygen = 5.00 g - 1.94 g
mass oxygen = 3.06 g
Determine the number of moles of each component by dividing the mass by its respective molar mass.
moles oxygen = mass oxygen / MM
moles oxygen = 3.06 g / 15.9994 g/mol
moles oxygen = 0.1912571721
moles chlorine = mass chlorine/ MM
moles chlorine = 1.94 g / 70.9060 g/mol
moles chlorine = 0.02736016698
Get the ratio between the two components to determine its empirical formula.
moles oxygen : moles chlorine = 0.1912571721 : 0.02736016698
moles oxygen : moles chlorine = 7 : 1
Hence, he empirical formula of this compound is ClO₇.
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explain why there is a difference in percent of mass change of the eggs in the different sucrose solutions.
There is a difference in the rate of mass change because eggs gain mass when kept in hypotonic solution, whereas they lose mass when kept in hypertonic solution.
What is hypertonic and hypotonic solution?Hypertonic solutions contain high concentrations of solutes compared to other solutions. The opposite solution with a lower concentration is called a hypotonic solution. Cells are considered hypotonic when placed in a hypertonic solution.
Hypotonic solution refers to a solution that contains a lesser amount of solute than the solute concentration of another solution through a semipermeable membrane.
Thus, eggs placed in high concentrations of sucrose lost the most weight. So the higher the sucrose concentration, the more water the egg will lose.
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how are the reactivities of tert-butyl bromide and 2-bromopropane related to the stabilities of the carbocations produced as intermediates in the reaction? you must fully justify your answer.
The reactivities of tert-butyl bromide and 2-bromopropane are related to the stabilities of the carbocations produced as intermediates in the reaction in several ways.
First, it is important to note that tert-butyl bromide has an electron-withdrawing group (carbonyl) attached to its aromatic ring. This makes it more reactive than 2-bromopropane because it is easier for tert-butyl bromide to achieve a favorable resonance structure.
Second, it is also important to note that tert-butyl bromide has a more stable carbocation intermediate than 2-bromopropane because it has a larger number of bonds between carbon atoms. This means that these bonds take longer to break apart during the transition state, which makes it harder for tert-butyl bromide's intermediate to form.
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concentrated nitric acid usually has a density of 1.4 g/ml and is 70% hno3 by mass (the rest is water). find the concentration of water in such a solution in mol/l.
The concentration of water in such a solution in mol/l is 0.0157 M.
Molar concentration is a measure of the concentration of a chemical species, particularly of a solute in an answer, in phrases of quantity of a substance per unit quantity of solution. In chemistry, the most commonly used unit for molarity is the range of moles consistent with liter, having the unit symbol mol/L or mol/dm³ in the SI unit.
Molarity (M) is the quantity of a substance in a certain volume of solution. Molarity is described as the moles of a solute consistent with liters of an answer. Molarity is likewise called the molar attention of a solution.
Calculation:-
The density of the solution is 1.41 g/mL.
1000 g of the solution will have a volume = Mass/ Density
= 1000 / 1.41
=709 ml.
The mass percent of nitric acid is 70%.
1000 g of the solution will have = 1000× 70/100
=690 g of nitric acid.
The molarity of the solution is = Mass of nitric acid / The molar mass of nitric acid ×Volume of solution.
Mass of nitric acid = 700 / 63×709
= 0.0157 M.
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why do primary alkyl halides typically undergo sn2 substitution reactions more rapidly than do secondary or tertiary alkyl halides
The SN2 reaction proceeds most quickly for primary carbons and there's less steric congestion for all of this backside assault.
Secondary as well as tertiary alkyl halides undergo the SN2 reaction more slowly than primary alkyl halides. Since there were only three little hydrogen atoms present, methyl halides interact in SN2 reactions the fastest among the simple alkyl halides.
Due to the fact that tertiary carbocations comprise three alkyl groups and secondary carbocations only have two, the former is more stable. Based on the inductive effect, tertiary carbocation is therefore more stable that secondary carbocation.
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NEED ANSWER IMMEDIATELY: 14. Problem: Uranium-238 has a mass number of 238 with 146 neutrons in the
nucleus. An isotope, Uranium-235 has 143 neutrons in the nucleus. What is
the atomic number of Uranium?
Answer:
92
Explanation:
given the table below that shows student's examples of proposed models of the atom: which model correctly describes the locations of protons and electrons in the wave-mechanical model of the atom?
The model accurately depicts where protons and electrons are in the wave. The proton is in the nucleus and the electron is where it is most likely to be. This is the mechanical model of the atom.
The electron was expected to move in circular orbits according to the Bohr model. On the other hand, orbitals are used in the wave mechanical model to characterise the electron positions. The two are not the same. Protons are located inside the nucleus in the wave mechanical model of an atom, but electrons are present where they are most likely to be.
A subatomic particle with a negative charge is an electron. A subatomic particle having a positive charge is called a proton. The strong nuclear force holds protons together in the nucleus of an atom. A type of subatomic particle without charge is the neutron (they are neutral).
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how many moles of potassium hydroxide would have to be added to 125 ml of a 0.420 m hydrocyanic acid solution, in order to prepare a buffer with a ph of 9.230?
0.021 moles of KCN are required, to prepare a buffer with a pH of 9.230
What is a buffer solution?A buffer, an aqueous solution consists of a mixture of a weak acid and its conjugate base or vice versa. Addition of a small amount of strong acid or strong base hardly changes the pH.
Given,
Volume = 125 mL
Concentration of HCN = 0.420 M
pH = 9.230
Moles of HCN = Volume × Concentration
= 0.125 × 0.420
= 0.0525 moles
HCN + KOH ⇄ KCN + H₂O
0.0525 + X ⇄ 0 [initially]
(0.0525 - X) + 0 ⇄ X [At equilibrium]
pH = pKₐ + log [salt]/[acid]
9.230 = 9.31 + log [salt]/[acid]
-0.08 = log [salt]/[acid]
0.83 = [salt]/[acid]
X / (0.0525 - X) = 0.83
X = 0.021 moles of KCN
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what if you measurd out more Fe then you calculated but the same amount of CUSO4 How would your amount of CU produced be affected
Answer:
Increase
Explanation:
Fe + CuSO4 - - > Fe2(SO)3 + Cu
If concentration of Fe increases, it will increase the frequency of collisions between the two reactants. Therefore the amount of Cu will also increase.
(a) how many milliliters of 0.155 m hcl are needed to neutralize completely 45.0 ml of 0.101 m ba(oh)2 solution?
29,322 milliliters of 0.155m hcl are needed to neutralize completely 45.0 ml of 0.101m ba(oh)2 solution Given that :
Hcl + Ba(oh)2 gives Bacl2 + 2h20
Molarity = mole of solute / volume of solution in liters
Molarity = 0.101 m
Volume = 45 ml
mole of solute (ba(0h)2) = Molarity * volume
= 0.101 * 45 ml
= 4.545
now we have to find the volume of hcl so,
again
molarity = mol solute/ volume of solution
volume of solution = mole solute / molarity
= 4.545 / 0.155m
= 29. 322 liters
= 29,322 ml
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The percent ionic character of a bond ______ with δen. An arbitrary value of ______ divides ionic from covalent bonding.
The percent ionic character of a bond increases with δen. An arbitrary value of 50% ionic character divides ionic from covalent bonding.
What is covalent bond explain?When two or more atoms share one or more couples of electrons, a covalent connection is created. These electrons are being drawn to the two neutrons and protons at the same time. A covalent bond is created when the difference between the two atoms' electrical configurations gets too small for an electrochemical reaction to happen and produce ions.
What characteristics do covalent bonds have?Bonds between atoms in covalent compounds share electrons. They possess distinctive physical characteristics, such as lower melting temperatures and electrical conductivity contrasted to ionic compounds, as a result of the sharing of electrons.
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b) if 3.25 moles of al and 1.92 moles of fe2o3 react together, what is the maximum amount of energy (dh) produced in this reaction?
The maximum amount of energy produced in this reaction is -1381.58J
What is mole?
It is defined as amount of a substance that contains exactly 6.02 × 10²³ ‘elementary entities’ of the given substance.
b) mole ratio = moles / balanced coefficient
mole ratio of Al = 3.25 mol/2 mol= 1.62
mole ratio of Fe2O3 = 1.92 mol/1 mole = 1.92
here , Al is the limiting reactant because of lower nole ratio, therefore it produces maximum amount of heat
Since 2 mole Al produces ∆H° rxn = -850.2J
1 mole Al produces ∆H° rxn = -850.2J/ 2
3.25 mole Al produce ∆H° rxn = (-850.2J/ 2) × 3.25
= -1381.58J
Hence energy ∆H = -1381.58J
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a system is compressed from 50 l to 5 l at a constant pressure of 10 atm. what is the amouint of work done?
When a system is compressed from 50 liters to 5 liters at a constant pressure of 10 atmospheres, how much work is done must be determined. Therefore, worked on is equal to p delta v less. P stands for pressure and refers to atmosphere. Therefore, we must convert it to newtons per square meter.
The equivalent of 10 atmosphere is 10 times 10 1, 3, and 5. The final volume and its beginning volume are the Newton perimeter square and changing volume. The total number of letters is five.
Additionally, we must afterwards convert into meter cube. Now, one letter equals ten to the power three minus m cube. In order to get 15 times 10 to the power of 3 meter cube, we increase it by 10 to the monastery's -50 L.
What is Constant pressure ?volume-temperature (constant pressure) When pressure is constant, a gas's volume and temperature are directly inversely related. When pressure is constant, the volume to temperature ratio remains constant. The term "Charles' law" or "Gay-law" Lussac's refers to this relationship.
When we say that the gases are under constant pressure, we mean that the pressures do not change depending on where we are in the cylinder. Both gases fill the entire space and, as you mentioned, exert different pressures. The partial pressure of a gas is the pressure it exerts within a mixture.
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what wavelength of light (in nm ) is emitted when the electron in a hydrogen atom relaxes from the n
102 nm wavelength of light is emitted when the electron in a hydrogen atom relaxes from n= 3 to n= 1
∆E = - Rh × ( 1/nf² - 1/ni² )
∆E = difference in energy between final and initial energy level (J )
R = Rydberg's constant
nf = final energy level
ni = initial energy level
nf = 3, ni = 1, Rh = 2.18 × 10-¹⁸
∆E = -2.18 × 10-¹⁸ ( 1/3² - 1/1² )
= 2.18 × 0.88 × 10-¹⁸ J
∆E = 1.93 × 10-¹⁸ J
∆E = hf = hc / λ
λ = (h × c) / ∆E
= ( 6.625 × 10-³⁴ × 3 × 10⁸) / 1.93 × 10-¹⁸
= 19.878 × 10-²⁶ / 1.93 × 10-¹⁸
= 10.299× 10-⁸
= 102.99×10-⁹
= 102 nm
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what will the evaporation of water and the formation of sea ice do to the salinity of water? group of answer choices
The ocean's salinity is raised by both sea ice production and ocean water evaporation. Ongoing inflow of fresh water from the rivers, fall of rain and snow, and the melting of ice constantly balance.
Why is water salinity important?It makes a significant contribution to conductance and influences many elements of the biochemistry in groundwaters as well as the biological activities that take place there. Temperature, pressure, and salinity all influence the physical properties of water, including its density its heat capacity.
How is water salinity influenced?Seawater salinity is impacted by rains, ice development, melting, and drainage. Seawater evaporate, leaving behind salts, which enhances their concentration and raises the salt of the water.
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what is the ph of a solution obtained by dissolving two extra-strength aspirin tablets, containing 450 mg of acetylsalicylic acid each, in 300 ml of water?
The ph of a solution obtained by dissolving two extra-strength aspirin tablets is 8.
The Concentration of solution is a measure of the quantity of solute that has been dissolved in a given amount of solvent or answer. A concentrated answer is one that has a rather huge quantity of dissolved solute.
Calculation:-
volume = 300 ml = 0.3 L
mass = 450 mg
molar mass C₉H₈O₄ = 180
mole = mass / molar mass
= 450/180
= 2.5 mol
Concentration = mole/volume
= 2.5 /0.3
= 8.33
PH = - llog[H+]
= 8.
The concentration of a substance is the quantity of solute found in a given amount of solution. Concentrations are normally expressed in terms of molarity, defined because of the variety of moles of solute in 1 L of answer.
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how to Calculate the molar heat capacity of iron in J • mol-1 • °C-1 . Its specific heat capacity is 0.4498 J • g-1 • °C-1
Based on the given specific heat capacity of iron, the molar heat capacity of iron =is 25.18 J/mol/°C.
What is the molar heat capacity of a substance?The molar heat capacity of a substance is the amount of heat required to raise the temperature of a unit mole of that substance by one degree.
The molar heat capacity is given by the formula below:
Molar heat capacity = heat change/mole of substance * temperature changeGiven the specific heat capacity of a substance, the molar heat capacity is obtained as follows
Molar heat capacity = specific heat capacity * molar mass
specific heat capacity of iron = 0.4498 J/g/°C
the molar mass of iron = 56 g/mol
Molar heat capacity of iron = 0.4498 J/g/°C * 56 g/mol
Molar heat capacity of iron = 25.18 J/mol/°C
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he quantum mechanical description of the shaped volumes of space occupied by electrons in an atom are called
Shaped volumes around the nucleus which are occupied by electrons are called Atomic Orbitals.
The quantum mechanical refinement of Bohr's orbit is an orbital. In contrast to his idea of a straightforward circular orbit with a constant radius, orbitals are regions of space that were calculated analytically and have varying possibilities of hosting an electron. A Quantum Mechanical Description of Electrons Around the Nucleus
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How many particles are in 0.75 moles of AgNO3?
Explanation:
Assume if its asking about molecule particle:
1 mol of AgNO3 = 6.022 x 10^23 molecules
0.75 mol of AgNO3 = 0.75 x 6.022 x 10^23
= 4.5165 x 10^23 molecules
Assume if its asking about atom particle:
AgNO3 has 5 elements
0.75 mol of AgNO3 = 0.75( 5 x 6.022 x 10^23)
= 2.2583 x 10^24 atoms
if the bromobenzene is added too quickly, what side product is formed (draw the structure in pen and name it!)?
If the bromobenzene is added too quickly, biphenyl is formed as the side product with the Grignard reagent.
What is Grignard reagent?
Grignard reagent is an organomagnesium halide which has the formula RMgX where R is alkyl or aryl group, Mg is magnesium, X is an halide.
When bromobenzene is added too quickly to the Grignard reagent, biphenyl is formed as a by-product. the formation of the side product is enhanced by high temperature. So, this reaction is carried out in low temperature.
Therefore, biphenyl is formed as side product when bromobenzene is added quickly to the Grignard reagent. The structure of biphenyl is two benzene rings joined together.
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2. when writing the chemical equation for a reaction, how do you indicate that a given reaction is dissolved in water? how do you indicate that a precipitate has formed as a result of the reaction?
When writing the chemical equation for a reaction, a reactant in aqueous solution is indicated with (aq); formation of a solid is indicated with (s).
Chemical equations serve to represent the transformation of reactants into products. For instance, the combination of iron (Fe) and sulphur (S) results in iron sulphide (FeS). The plus symbol indicates that sulphur and iron react to form FeS.
The four primary categories of chemical reactions are single displacement, double displacement, breakdown, and synthesis. But keep in mind that other people refer to these reactions by other names.
They are equations that represent chemical reactions using chemical formulae and symbols. In a chemical equation, the reactants are represented on the left and the products are on the right. A symbol that denotes the reaction's direction separates these two entities.
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why is longitudinal diffusion a more serious problem in gas chromatography than in liquid chromatography?
The longitudinal diffusion a more serious problem in gas chromatography than in liquid chromatography because the diffusion coefficient is much more larger in gas than the liquid.
What is Chromatography?Chromatography is a type of laboratory technique which is performed for the separation of the mixture of different elements into its components. The mixture firstly dissolved in a fluid solvent which is known as the mobile phase, that carries it through a system at which the material called the stationary phase is fixed.
Not all molecules present in the same solute show same behavior. Different molecules show different behaviour. This is due to mainly three reason which arr given as below:
Resistance to the transfer of matter. Longitudinal diffusionSwirl diffusionThe molecules of solute moves in different direction in the stationary phase, it is due to porosity of the particle that form it.
Thus, we concluded that the longitudinal diffusion a more serious problem in gas chromatography than in liquid chromatography because the diffusion coefficient is much more larger in gas than the liquid.
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