Answer:
n=4, l= 2, ml=0, ms=+1/2
Explanation:
Arsenic (As) is a group 15 element with ground state electronic configuration; 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3. Note that the outer orbitals are 4s2 4p3(corresponding to ns2np3 for group 15 elements).
We can see that the ground state electronic configuration of arsenic does not contain a 4d orbital from the electronic configuration shown above. However, the option chosen as the answer, portrays an electron in a 4d orbital (n=4, l=2). This implies that the electron cannot be seen in the ground state electronic configuration of arsenic, hence the answer.
A ground state atom of As could not have any electrons with n = 4, ℓ = 2, mℓ = 0, ms = +½ .
The given atom:
Arsenic (As), with atomic number 33The electronic configuration of Arsenic is written as follows;
[tex]1s^2 \ 2s^2 \ 2p^6 \ 3s^2 \ 3p^6 \ 4s^2 \ 3d^{10} \ 4p^3[/tex]
The group of the given element can be obtained from the electronic configuration as shown below;
[tex]4s^2 \ 4p^3 \ --> \ group \ 15 \ element[/tex]
From the given options, the ground state atom of Arsenic cannot have electron in the following orbital;
[tex]n= 4, \ l=2: \ \ -->\ 4d \ - \ orbital[/tex]
Note:
[tex]n=4, \ l=0 : \ \ --> \ 4s \ - \ orbital[/tex]
Thus, we can conclude that a ground state atom of As could not have any electrons with n = 4, ℓ = 2, mℓ = 0, ms = +½ .
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how many calories are in a 50g package of peanuts
Answer:
284 calories
Explanation:
There are 284 calories in 50 grams of peanuts.
Calorie breakdown: 73% fat, 11% carbs, 17% protein.
Fill in the [?]:
234 cm = [?] m
Answer:
2.34 mExplanation:
As we know:1 meter= 100 cmHere,
To do: Convert 234 cm into m
[tex] = \frac{234}{100} \\ = 2.34 \: \: m[/tex]
Hope this helps...
Good luck on your assignment..
Answer:
2.34 metres
Explanation:
→ First we need to utilise the fact that there is 100 cm in one metre
100 cm = 1 metre
→ Then we utilise ratio's
100 cm : 1 metre
234 cm : ? metre
→ (234 ÷ 100) × 1 = (2.34) × 1 = 2.34
234 cm = 2.34 metres
Write the empirical formula
Answer:
See the explanation and answer below.
Explanation:
In chemistry, the empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in a compound. The formula gives the proportions of the elements present in a compound but not the actual arrangement of atoms.
[tex]\mathrm{Molecular \:Formula}\quad \quad |\quad \quad \mathrm{Empirical \:Formula}[/tex]
[tex]1.\:\:\:NH_4OH\quad | \quad H_5NO[/tex] (Ammonium hydroxide)
[tex]2.\:\:\:Fe(OH)_3\quad |\quad FeH_3O_3[/tex] (Iron(III) hydroxide)
[tex]3.\:\:\:NH_4C_2H_3O_2\quad |\quad C_2H_7NO_2[/tex] (Ammonium acetate)
[tex]4.\:\:\:Fe(C_2H_3O_2)_3\quad |\quad C_6H_9FeO_6[/tex] (Iron(III) Acetate)
I hate chemistry but best regards!
Write a balanced equation for the single-displacement reaction of Al(s) with CuSO4(aq). Include states of matter in your answer.
Answer:
2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
Explanation:
Let's consider the single displacement reaction of Al(s) with CuSO₄(aq). Copper has a higher reduction potential than aluminum, so aluminum will take the place of copper to form aluminum sulfate and metallic copper. The corresponding balanced chemical equation is:
2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
The chemical equation is 2 Al(s) + 3 CuSO₄(aq) ⇒ 3 Cu(s) + Al₂(SO₄)₃(aq)
Chemical equation:
here we considered the single displacement reaction of Al(s) with CuSO₄(aq). Also, Copper contained a higher reduction potential as compared to aluminum, due to this aluminum will take the place of copper to create aluminum sulfate and metallic copper. So the above should be the balance chemical equation.
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ONE ANSWER
Which statement describes an effect of large asteroid and comet impacts?
They may cause continents to move.
O They may cause small craters on Earth's surface.
O They may cause changes limited to within the crater,
O They may kick up dust and pollute Earth's atmosphere.
The correct answer is D. They may kick up dust and pollute Earth's atmosphere.
Explanation:
The impact of a large asteroid or comet is a major event that leads to major changes in ecosystems. One of the effects that can be expected is an important increase in dust because one of the components of asteroids and comets is dust, which would be released during the impact. Also, this dust might interact with components from the soil and the atmosphere creating a cloud, acting as a pollutant. According to this, the expected effect is "They may kick up dust and pollute Earth's atmosphere"
Answer:
They may kick up dust and pollute Earth’s atmosphere.
Explanation:
;ojehfa;oslkdfj;sldkfj
What is the boiling point of an aqueous solution that has a vapor pressure of 23.0 torr at 25 ∘C? (P∘H2O=23.78 torr; Kb= 0.512 ∘C/m).
Answer:
Boiling point of the solution is 100.964°C
Explanation:
In this problem, first, you must use Raoult's law to calculate molality of the solution. When you find the molality you can obtain the boiling point elevation because of the effect of the solute in the solution (Colligative properties).
Using Raoult's law:
Psol = Xwater × P°water.
As vapour pressure of the solution is 23.0torr and for the pure water is 23.78torr:
23.0torr= Xwater × 23.78torr.
0.9672 = Xwater.
The mole fraction of water is:
[tex]0.9672 = \frac{X_{H_2O}}{X_{H_2O}+X_{solute}}[/tex]
Also,
[tex]1 = X_{H_2O}+X_{solute}[/tex]
You can assume moles of water are 0.9672 and moles of solute are 1- 0.9672 = 0.0328 moles
Molality is defined as the ratio between moles of solute (0.0328moles) and kg of solvent. kg of solvent are:
[tex]09672mol *\frac{18.01g}{1mol}* \frac{1kg}{1000g} = 0.01742kg[/tex]
Molality of the solution is:
0.0328mol Solute / 0.01742kg = 1.883m
Boiling point elevation formula is:
ΔT = Kb×m×i
Where ΔT is how many °C increase the boiling point regard to pure solvent, Kb is a constant (0.512°C/m for water), m molality (1.883m) and i is Van't Hoff factor (Assuming a i=1).
Replacing:
ΔT = 0.512°C/m×1.882m×1
ΔT = 0.964°C
As the boiling point of water is 100°C,
Boiling point of the solution is 100.964°C
Boiling point of the solution is 100.964°C.
Raoult's Law:It says that the vapor pressure of a solvent above a solution is equal to the vapor pressure of the pure solvent at the same temperature scaled by the mole fraction of the solvent present.
Using Raoult's law:[tex]P_{sol} = X_{water} * P^o_{water}[/tex]
Given:
Vapor pressure of the solution = 23.0torr Vapor pressure of pure water = 23.78torrSubstituting the values:
[tex]23.0torr = X_{water} * 23.78torr\\\\0.9672 = X_{water}[/tex]
The mole fraction of water is:[tex]0.9762=\frac{X_{water}}{X_{water}+X_{solute}}[/tex]
The sum of the mol fractions of water and solute is 1.
We can consider,
Moles of water = 0.9672
Moles of solute = 1- 0.9672 = 0.0328 moles
Calculation for Molality:It is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.
[tex]\text{Mass of solvent}=0.9672*\frac{18g/mol}{1mol} *\frac{1kg}{1000g}\\\\\text{Mass of solvent} =0.01745kg[/tex]
Molality of the solution is:[tex]\text{Molality}= \frac{0.0328mol}{0.01742kg} \\\\\\text{Molality}= 1.883m[/tex]
Calculation of Boiling point:[tex]\triangle T = K_b*m*i[/tex]
Substituting the values in the above formula:
[tex]\triangle T = 0.512^oC/m*1.882m*1\\\\\triangle T = 0.964^oC[/tex]
Thus, Boiling point of the solution is 100.964°C, since boiling point of water is 100°C.
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Click the "draw structure" button to launch the drawing utility. Draw the product of the reaction of propanal with lithium aluminum hydride, followed by water.
Answer:
Product: propan-1-ol
Explanation:
IIn this case, we have to remember that [tex]LiAlH_4[/tex] is a reduction agent. So, this is a reduction reaction. The [tex]LiAlH_4[/tex] has the ability to produce hydride ions [tex]H^-[/tex]. This ion can attack the carbonyl group generating a negative charge in the oxygen. In the next step, the negative charge in the oxygen can attack a water molecule to protonate the molecule and produce propan-1-ol.
See figure 1
I hope it helps!
Silver crystallizes in a face-centered cubic structure. What is the edge length of the unit cell if the atomic radius of silver is 144 pm?
Answer:
Edge length of the unit cell is 4.07x10⁻¹⁰m
Explanation:
In a face-centered cubic structure, the edge, a, could be obtained using pythagoras theorem knowing the hypotenuse of the unit cell, b, is equal to 4r:
a² + a² = b² = (4r)²
2a² = 16r²
a = √8 r
That means edge lenght is = √8 r
adius
As radius of Silver is 144pm = 144x10⁻¹²m:
a = √8 r
a = √8 ₓ 144x10⁻¹²m
a = 4.07x10⁻¹⁰m
Edge length of the unit cell is 4.07x10⁻¹⁰mg compute the specific heat capacity at constant volume of nitrogen gas. the molar mass of N2 is 29.0 You warm 1.8 kg ov water at a constant volume from 21 C to 30.5 C in a kettle
Complete question:
(a) compute the specific heat capacity at constant volume of nitrogen gas. the molar mass of N₂ is 29.0 You warm 1.8 kg of water at a constant volume 1.00 L from 21 C to 30.5 C in a kettle. For the same amount of heat, how many kilograms of 21∘C air would you be able to warm to 30.5∘C ?
(b) What volume (in liters) would this air occupy at 21∘C and a pressure of 1.00 atm? Make the simplifying assumption that air is 100% N₂
Answer:
(a) The specific heat capacity of N₂ is 715.86 J/kg.K
(b) The volume the air occupy at 21∘C is 8784.29 Liters
Explanation:
Given;
M is the molar mass of N₂ = 29 x 10⁻³ kg/mol
specific heat of N₂ at constant volume, Cv = 20.76 J/mol.K
(a)
The specific heat capacity of N₂ is calculated as;
[tex]C = \frac{C_v}{M} \\\\C = \frac{20.76}{29 *10^{-3}} \\\\C = 715.86 \ J/kg.K[/tex]
(b) heat capacity of water;
Q = mcΔθ
where;
c is the specific heat capacity of water = 4200 J/kg.K
m is mass of water, = 1.8 kg
Δθ is change in temperature, = 30.5 - 21 = 9.5 °C
Q = 1.8 x 4200 x 9.5
Q = 71820 J
Mass of nitrogen gas N₂, at this quantity of heat;
[tex]m_{N_2} = \frac{Q}{C*\delta \theta} \\\\m_{N_2} = \frac{71820}{715.86*9.5}\\\\m_{N_2} = 10.56 \ kg[/tex]
The volume this air occupy at 21∘C
Apply ideal gas law;
[tex]PV = nRT = \frac{m}{M} RT[/tex]
[tex]PV = \frac{mRT}{M} \\\\V = \frac{mRT}{MP}\\\\V = \frac{10.56(kg)*8.314*10^3(L.Pa/mol.K)*294(K)}{29*10^{-3}(kg)1.01325*10^5 (Pa)}\\\\V = 8784.29 \ Liters[/tex]
The combustion of propane may be described by the chemical equation C3H8(g)+5O2(g)⟶3CO2(g)+4H2O(g) How many grams of O2(g) are needed to completely burn 56.3 g C3H8(g)?
Answer:
204.7 g
Explanation:
(taking the atomic mass of C, H, O as 12, 1 and 16 respectively).
no. of moles of C3H8 burnt = 56.3 / (12x3 + 1x8)
= 1.27955 mol
From the equation, the mole ratio of C3H8 : O2 = 1:5
Hence,
the no. of moles of O2 required will be
=1.27955 x 5
= 6.397727 mol
Mass of O2 required = 6.397727 x (16x2)
= 204.7 g
If solid ammonium fluoride (NH4F) is dissolved in pure water, will the solution be acidic, neutral, or basic?
Answer:
Dissolving NH4F in water will form a weak acidic solution.
Explanation:
That it is a weak acid solution means that it has a pH below 7 but close to the value, that is, it does not contain as many acids as those substances that are around a pH of 1 to 4, generally weak acids have a pH approximately 5 to 6
The solution of solid ammonium fluoride in pure water has been slightly acidic in nature.
Ammonium fluoride has been an ionic compound formed by the interaction of cationic ammonia and anionic fluoride ions. The dissolution of ionic compounds will result in the compound in its dissociated ionic state.
The dissociation results in the formation of ammonium cation. The ammonium has been a strong acid.
The resulted anion has been fluoride. It has been a strong base, but slightly weaker than ammonia.
Thus the resultant solution will result in slightly acidic nature.
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Given the specific heat for aluminum is 0.900 J/g.°C, how much heat is released when a 3.8 g sample
of Al cools from 450.0°C to 25°C?
A. 1.5 kJ
B. 54 J
C. 60J
D. 1.7 kJ
E. 86 J
Answer:
Q = 1.5 kJ
Explanation:
It is given that,
The specific heat for aluminum is 0.900 J/g°C
Mass of sample, m = 3.8 g
Initial temperature, [tex]T_i=450^{\circ} C[/tex]
Final temperature, [tex]T_f=25^{\circ} C[/tex]
We need to find the heat released. The amount of heat released is given by the formula:
[tex]Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\Q=3.8\times 0.9\times (25-450)\\\\Q=1453.5\ J\\\\Q=1.45\ kJ[/tex]
or
[tex]Q=1.5\ kJ[/tex]
So, the correct option is (A) i.e. 1.5 kJ.
The molecular weight of table salt, NaCl, is 58.5 g/mol. A tablespoon of salt weighs 6.37 grams. Calculate the number of moles of salt in one tablespoon.
Finally, solve (remember significant figures):
Answer:
0.109 mol/tablespoon
Explanation:
6.37 g/ 58.5 mol = 0.10888888 mol (0.109 significantly)
Answer:
A: 0.109
Explanation:
Edge 2020
You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution when exactly 13 mL of base had been added was 2.75. You notice that the concentration of the unknown acid was 0.1 M.
a. What are the Ka and the pKa of your unknown acid? (Show work)
b. After finishing your calculations, you discover that the actual concentration of the unknown acid was 0.35 M. How would this affect your calculation of the pKa?
Answer:
a. 1.78x10⁻³ = Ka
2.75 = pKa
b. It is irrelevant.
Explanation:
a. The neutralization of a weak acid, HA, with a base can help to find Ka of the acid.
Equilibrium is:
HA ⇄ H⁺ + A⁻
And Ka is defined as:
Ka = [H⁺] [A⁻] / [HA]
The HA reacts with the base, XOH, thus:
HA + XOH → H₂O + A⁻ + X⁺
As you require 26.0mL of the base to consume all HA, if you add 13mL, the moles of HA will be the half of the initial moles and, the other half, will be A⁻
That means:
[HA] = [A⁻]
It is possible to obtain pKa from H-H equation (Equation used to find pH of a buffer), thus:
pH = pKa + log₁₀ [A⁻] / [HA]
Replacing:
2.75 = pKa + log₁₀ [A⁻] / [HA]
As [HA] = [A⁻]
2.75 = pKa + log₁₀ 1
2.75 = pKaKnowing pKa = -log Ka
2.75 = -log Ka
10^-2.75 = Ka
1.78x10⁻³ = Kab. As you can see, the initial concentration of the acid was not necessary. The only thing you must know is that in the half of the titration, [HA] = [A⁻]. Thus, the initial concentration of the acid doesn't affect the initial calculation.
a. The value of Ka and pKa of the unknown acid should be 1.78x10⁻³ and 2.75.
b. It should be not relevant.
Calculation of the Ka and the pKa:a. The neutralization of a weak acid, HA, with a base can determine Ka of the acid.
Since
Equilibrium is:
HA ⇄ H⁺ + A⁻
And Ka is defined as:
Ka = [H⁺] [A⁻] / [HA]
The HA reacts with the base, XOH,
So,
HA + XOH → H₂O + A⁻ + X⁺
In the case when you add 13 mL, the moles of HA should be half of the initial moles and, the other half, will be A⁻
Like
[HA] = [A⁻]
Now
pH = pKa + log₁₀ [A⁻] / [HA]
2.75 = pKa + log₁₀ [A⁻] / [HA]
Since
2.75 = pKa + log₁₀ 1
2.75 = pKa
Knowing pKa = -log Ka
2.75 = -log Ka
10^-2.75 = Ka
1.78x10⁻³ = Ka
b. Since the initial concentration of the acid was not necessary. The only thing should be that in the half of the titration, [HA] = [A⁻]. Thus, the initial concentration of the acid doesn't affect the initial calculation.
What is the mass of 1.56 X 10^24 formula units of Na2SO4?
Answer:
[tex]m=368 g[/tex]
Explanation:
Hello,
In this case, in order to compute the required mass, we first must notice that 6.022x10²³ formula units of sodium sulfate contain 1 mole of such compound (Avogadro's relationship). Moreover, one mole of sodium sulfate contains 142.04 g, which is in fact, the molar mass. Thereby, the required mass is computed via the following mole-mass-particles relationship:
[tex]m=1.56x10^{24}f.u*\frac{1mol}{6.022x10^{23}f.u}*\frac{142.04g}{1mol} \\\\m=368 g[/tex]
Regards.
Calculate the combustion of gaseous dimethyl ether CH 3 OCH 3 (g)+3O 2 (g) 2CO 2 (g)+3H 2 O(l) using standard molar enthalpies of formation Molecule AH H l ^ 0 (k)/mol) CH 3 OCH 3 (g) - 184.1
Answer:
[tex]\Delta _cH=-1328.3kJ/mol[/tex]
Explanation:
Helllo,
In this case, for the given chemical reaction in gaseous state:
[tex]CH_3OCH_3+3O_2\rightarrow 2CO_2+3H_2O[/tex]
We comoute the combustion enthalpy as the reaction enthalpy for one mole of fuel (dimethyl ether) considering the formation enthalpy of each given substance and whether they are reactants (subtracting) or products (adding), therefore we write:
[tex]\Delta _cH=2*\Delta _fH_{CO_2}+3*\Delta _fH_{H_2O}-\Delta _fH_{CH_3OCH_3}-3*\Delta _fH_{O_2}[/tex]
Whereas the formation enthalpies for carbon dioxide, water, dimethyl ether and oxygen are -393.5, -241.8, -184.1 and 0 kJ/mol respectively, thereby, the combustion enthalpy turns out:
[tex]\Delta _cH=2(-393.5)+3*(-241.8)-(-184.1)-3(0)\\\\\Delta _cH=-1328.3kJ/mol[/tex]
Notice that enthalpy of formation of oxygen is zero since forming an element has no chemical sense, it just exists as it has been early demonstrated.
Regards.
Which type of rock is formed from existing rock or organisms?
Answer:
Sedimentary rocks
Explanation:
My explanation is that when an animal decomposes it body returns to the ground eventually being used in the rock cycle and rocks form this through the rock cycle when broken down by weathering and erosion.
Hope this helps you
Answer:
sedimentary rocks
They form from deposits that accumulate on the Earth's surface.
Compound X has the formula C7H14. X reacts with one molar equivalent of hydrogen in the presence of a palladium catalyst to form 3-methylhexane. Treatment of X with ozone follwed by zinc in aqueous acid gives a ketone plus formaldehyde (CH2=O). What is the structure of X?
Answer:
3-methylenehexane
Explanation:
In this case, we have two clues.
1) The hydrogenation reaction
2) The ozonolysis reaction
See figure 1.
With this in mind, lets analyze each clue. In the first reaction, we know that only 1 molecule of [tex]H_2[/tex] is added to the unknown molecule. This indicates that we only have 1 double bond in the molecule. Now, the next question is where is placed the double bond?
To answer this question, we have to use the second clue. In the ozonolysis reaction, a double bond is broken and is replaced with a carbonyl group. If, formaldehyde is formed the double bond is formed with a primary carbon. The primary carbons in the structure (given in the first reaction: 3-methylhexane) are carbons 1, 6, and 7. So, the double bond can be placed between carbons:
a) 6 and 5
b) 7 and 3
c) 1 and 2
To decide which one is the position of the double bond we have to keep in mind the second product of the ozonolysis reaction a ketone. With this in mind, the carbon bonded to the primary one (deduced by the formaldehyde) it has to be a tertiary carbon. The only option that has a primary carbon bonded to tertiary carbon is b). (See figure 2)
Finally, with this in mind the structure is 3-methylenehexane. To be sure, we can check the formula for the compound, [tex]C_7H_1_4[/tex] and the reactions. (See figure 3)
I hope it helps!
Discuss the contrary aspect of proton NMR and C-13 NMR by elucidating the structure of 2 chloro pentanal?
Answer:
See explanation
Explanation:
1H NMR
In the 2-chloro-pentanal we have 4 different types of hydrogens. Therefore, we will have 4 different signals. (See figure 1)
Red hydrogen
For the red hydrogens we have only 1 neighbor. So, if we follow the n+1 rule we can calculate the multiplicity of this hydrogen. In this case a doublet.
Blue hydrogens
In this case, we have 3 neighbors (one in the right, two in the left). Therefore we will have a quartet.
Purple hydrogens
For these hydrogens, we have also will have a quartet, because we have 3 neighbors (one in the right, two in the left).
Green hydrogens
In the green hydrogen,s we have 5 neighbors (2 in the right 3 in the left). Therefore a sextet would be produced.
Orange hydrogens
Finally, in these hydrogens, we have 2 neighbors. Therefore a triplet is expected.
13C NMR
For the 13C NMR, we have again 4 different kinds of carbons. Therefore we will have 4 signals. The most deshielded carbon, in this case, is the red one (see figure 2), so this carbon would be on the left side (around 190). Then the next deshield carbon is the blue one, due to the "Cl" atom placed on this carbon.
I hope it helps!
Name the precipitate that forms when aqueous solutions of barium nitrate and potassium sulfate are mixed.
Answer:
barium sulfate BaSO₄
Explanation:
When aqueous solutions of barium nitrate and pottasion sulfate are mixed, a precipitate of barium sulfate BaSO₄ forms.
To solve this we must know the concept of chemical reaction. BaSO₄, barium sulfate is the precipitate formed when barium nitrate and potassium sulfate is reacted.
What is chemical reaction?Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, double displacement reaction.
In double displacement reaction the two compounds react with each other. The cations of each compound exchange their places with one another. BaSO₄, barium sulfate is the precipitate formed when barium nitrate and potassium sulfate is reacted.
Therefore BaSO₄, barium sulfate is the precipitate formed when barium nitrate and potassium sulfate is reacted.
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Products: 1-methylcyclohexene, 3-methylcyclohexene, methylenecyclohexane
A) Which kind of mechanism can better account for the product mixture obtained from the dehydration of cis and trans 2-methylcyclohexanol: E1, E2, or a combination of the two?
B) Write detailed mechanisms explaining the formation of all the observed products.
Answer:
See explanation
Explanation:
The reaction that we are considering here is quite a knotty reaction. It is difficult to decide if the mechanism is actually E1 or E2 since both are equally probable based on the mass of scientific evidence regarding this reaction. However, we can easily assume that the methylenecyclohexane was formed by an E1 mechanism.
Looking at the products, one could convincingly assert that the reaction leading to the formation of the two main products proceeds via an E1 mechanism with the formation of a carbocation intermediate as has been shown in mechanism attached to this answer. Possible rearrangement of the carbocation yields the 3-methylcyclohexene product.
Where would you find the following symbol on a diagram of a water molecule: δ+ ?
Answer:
On the 2 hydrogen atoms.
Explanation:
δ+ indicates the atom has a lower electronegativity than the other atom it is bonded with. This only exist in polar covalent bonds, where the 2 atoms have different electronegativity values. When they have different electronegativity values, the one with higher electronegativity has a higher tendency to "pull" the shared electrons towards itself, they have a δ- symbol.
Back to H2O, since the electronegativity of elements increases from left to right horizontally and upwards vertically in the periodic table (except for noble gases, they are unreactive. Note that fluorine has the highest electronegativity), O atom has a higher electronegativity than hydrogen (hydrogen sits at the centre top of the table). hence, we can find δ+ on the hydrogen atoms.
What is the skeleton equation of the following?
Potassium oxide
Magnesium oxide
Sulfur trioxide
Sodium chloride
Answer:
Explanation:
Skeleton equation is opposite of word equation because here you use chemical formulas to write down the components.
Potassium Oxide = K2O
Magnesium Oxide = MgO
Sulfur Trioxide = SO3
Sodium Chloride = NaCl
4. If 13 percent of the carbon-14 in a sample of cotton cloth remains, what's the approximate age of the cloth? Show your work
The approximate age of the cloth is 17190 years.
We'll begin by calculating the number of half-lives that has elapsed. This can be obtained as follow:
Original amount (N₀) = 100%Amount remaining (N) = 13%Number of half-lives (n) =?2ⁿ = 100 / 13
2ⁿ = 8
2ⁿ = 2³
n = 3
Finally, we shall determine the age of the cloth.
Half-life (t½) = 5730 yearsNumber of half-lives (n) = 3Time (t) =?t = n × t½
t = 3 × 5730
t = 17190 years
Thus, the approximate age of the cloth is 17190 years
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Which of the following describes green design?
A. Materials that will fail in a predictable and safe way
B. The use of new engineering technologies in building construction
c. Building structures made of composite materials to make them
safer
D. Materials and design techniques that reduce the negative
environmental impact of a structure
Answer: materials and design Techniques that reduce the negative environmental impact of a structure
Explanation:
A certain radioactive isotope decays at a rate of 0.2% annually. Determine the half-life of this isotope, to the nearest year.
Answer:
The half-life of the radioactive isotope is 346 years.
Explanation:
The decay rate of the isotope is modelled after the following first-order linear ordinary differential equation:
[tex]\frac{dm}{dt} = -\frac{m}{\tau}[/tex]
Where:
[tex]m[/tex] - Current isotope mass, measured in kilograms.
[tex]t[/tex] - Time, measured in years.
[tex]\tau[/tex] - Time constant, measured in years.
The solution of this differential equation is:
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex]
Where [tex]m_{o}[/tex] is the initial mass of the isotope. It is known that radioactive isotope decays at a yearly rate of 0.2 % annually, then, the following relationship is obtained:
[tex]\%e = \frac{m(t)-m(t+1)}{m(t)}\times 100\,\% = 0.2\,\%[/tex]
[tex]1 - \frac{m(t+1)}{m(t)} = 0.002[/tex]
[tex]1 - \frac{m_{o}\cdot e^{-\frac{t+1}{\tau} }}{m_{o}\cdot e^{-\frac{t}{\tau} }}=0.002[/tex]
[tex]1 - e^{-\frac{1}{\tau} } = 0.002[/tex]
[tex]e^{-\frac{1}{\tau} } = 0.998[/tex]
[tex]-\frac{1}{\tau} = \ln 0.998[/tex]
The time constant associated to the decay is:
[tex]\tau = -\frac{1}{\ln 0.998}[/tex]
[tex]\tau \approx 499.500\,years[/tex]
Finally, the half-life of the isotope as a function of time constant is given by the expression described below:
[tex]t_{1/2} = \tau \cdot \ln 2[/tex]
If [tex]\tau \approx 499.500\,years[/tex], the half-life of the isotope is:
[tex]t_{1/2} = (499.500\,years)\cdot \ln 2[/tex]
[tex]t_{1/2}\approx 346.227\,years[/tex]
The half-life of the radioactive isotope is 346 years.
you mix 45 ml of .20M KOH in calorimeter. The temperature of both reactions before mixing is 21.5 C. The Cp of the calorimeter was 36 J/K. If the final temperature of the mixture is 23.6 C, what is the enthalpy change per mole of water produced?
Answer:
THE ENTHALPY CHANGE PER MOLE OF KOH IS 8400 Joules/ mole OF HEAT.
Explanation:
Heat = heat capacity * change in temperature
Heat capacity = 36 J/K
Temperature of the mixture before mixing = 21.5 C
Temperature of mixtire after mixing = 23.6 C
Calculate the change in temperature:
Change in temperature = 23.6 C - 21.5 C = 2.1 C
Heat = 36 * 2.1
Heat = 75.6 J of heat
In essence, 45 ml of 0.20 M of KOH produces 75.8 J of heat
The enthalpy change per mole of water:
It is important t obtain the number of moles involved in the reaction of 45 mL of 0.20 M of KOH
n = C V
n = 0.20 M * 45 *10^-3
n = 0.009 moles
Since number of moles = mass / molar mass
The mass of 45 ml of 0.20 M of KOH is then:
Molar mass = ( 39 + 16 + 1) g/mol = 56 g/mol
Mass = number of moles * molar mass
Mass = 0.009 * 56
Mass = 0.504 g
So therefore 0.504 g of KOH produces 75.6 J of heat
1 mole of KOH will produce x J of heat
1 mole of KOH = 56 g of KOH
0.504 g = 75.6 J
56 g = x J
x J = 56 * 75.6 / 0.504
x J = 8400 J / mole of KOH
Q3. Which of the following objects are chiral and which are achiral? a
club b. teacup c. football d. corkscrew e. tennis racket f. shoe g. portrai
pencil (8 marks)
Q4. Write a structure for each of the compounds listed. Explain why th
name given is incorrect, and give a correct name in each case (20 mai
a. l-methylbutane
b. 1.1,3-trimethylhexane
c. 5-octyne
d. 2-ethyl-1-propanol
e. 2.2-dimethyl-3-butanol
Submit via aduwiejuah a uds.edu.gh and deadline for submission is
July, 2020 at 11:00 AM.
Answer:
See explanation
Explanation:
In this question, we have to follow the IUPAC rules. Lets analyze each compound:
a. 1-methylbutane
In this compound we have a chain of 5 carbons, so the correct name is Pentane.
b. 1,1,3-trimethylhexane
In this compound, we longest chain is made of 7 carbons, so, we have to use the name "heptane". Carbon one would be the closet one to the methyl group, so the correct name is 2,4-dimethylheptane.
c. 5-octyne
In this case, carbon 1 would be the closet one to the triplet bond. With this in mind, the correct name is oct-3-yne.
d. 2-ethyl-1-propanol
In this compound, we longest chain is made of 4 carbons, so, we have to use the name "butane". Carbon one would be the carbon with the "OH" group, so the correct name is 2-methylbutan-1-ol.
e. 2.2-dimethyl-3-butanol
In this case, carbon 1 would be the closet one to the "OH". With this in mind, the correct name is 3,3-dimethylbutan-2-ol.
See figure 1
I hope it helps!
Calculate the pH of a 0.0255 M solution of ammonium bromide (NH4Br). The Kb of ammonia is 1.76 x 10-5
Answer:
5.42
Explanation:
Step 1: Consider the dissociation of NH₄Br
NH₄Br(aq) ⇒ NH₄⁺(aq) + Br⁻(aq)
Br⁻ is the conjugate base of HBr, a strong acid, so it doesn´t react with water. NH₄⁺ is the conjugate acid of NH₃, so it does react with water.
Step 2: Consider the acid reaction of NH₄⁺
NH₄⁺(aq) + H₂O(l) ⇄ NH₃(aq) + H₃O⁺(aq)
Step 3: calculate the acid dissociation constant for NH₄⁺
We will use the following expression.
[tex]K_a \times K_b = K_w\\K_a = \frac{K_w}{K_b} = \frac{1.00 \times 10^{-14} }{1.76 \times 10^{-5}} = 5.68 \times 10^{-10}[/tex]
Step 4: Calculate the concentration of H₃O⁺
We will use the following expression.
[tex][H_3O^{+} ]= \sqrt{K_a \times C_a } = \sqrt{5.68 \times 10^{-10} \times 0.0255 } = 3.81 \times 10^{-6}M[/tex]
Step 5: Calculate the pH
We will use the following expression.
[tex]pH = -log [H_3O^{+} ] = -log (3.81 \times 10^{-6}) = 5.42[/tex]
The pH of 0.0255 M solution should be 5.42.
Calculation of the pH of 0.0255 M solution:Since we know that
ka * kb = kw
So,
ka = kw/kb
= 1.00*10^-14 / 1.76*10^-5
= 5.68*10^-10
Now the concentration of H3O should be
= √ka * Ca
= √5.68*10^-10 * 0.0255
= 3.81*10^-6M
Now the pH value should be
= -log(H3O+)
= -log(3.81*10^-6)
= 5.42
hence, The pH of 0.0255 M solution should be 5.42.
Learn more about pH here: https://brainly.com/question/23506014
Which statement describes solstices?
They occur when the Sun reaches its highest or lowest point in the sky.
O They affect the amount of sunlight in the Southern Hemisphere in May.
They contribute to the cycling of winters all year long in the Northern Hemisphere.
O They increase the amount of rays from the Sun directly received in the Southern Hemisphere.
Answer:
Option A (They happen as the Sun hits its maximum and minimum level throughout the sky) is the correct option.
Explanation:
Solstice seems to be the moment whereas at noon this same sun achieved its maximum as well as minimum position, actually results throughout the year's shortest as well as biggest days. We currently believe that perhaps the solstice seems to be an apocalyptic event, exacerbated either by the tilt of the globe’s axis and therefore its direction of movement in an elliptical orbit. Globe's rotation not everyone's travel time from either the sun was what was causing winter or even just summer.Some other options given should not be in accordance with the given context. So, the correct approach would've been option A.
Answer:
A: They occur when the Sun reaches its highest or lowest point in the sky.
Edge 2022
have a good spring break!