Answer:
Keq = 0.217
Explanation:
Let's determine the equilibrium reaction.
In gaseous state, water vapor can be decomposed to hydrogen and oxygen and this is a reversible reaction.
2H₂(g) + O₂(g) ⇄ 2H₂O (g) Keq
Let's make the expression for the equilibrium constant
Products / Reactants
We elevate the concentrations, to the stoichiometry coefficients.
Keq = [H₂O]² / [O₂] . [H₂]²
Keq = 0.250² / 0.8 . 0.6² = 0.217
How many Liters of 0.968M solution can be made if 0.581 moles of solute are added? Group of answer choices 0.600 L 60 mL 0.562 L 1.00 L
Answer:
0.6L
Explanation:
The formula of molarity is molSolute/litreSolution
[tex]0.968M=\frac{0.581}{LitreSolution} \\\\LitreSolution=\frac{0.581}{0.968} \\LitreSolution=0.6L[/tex].
When two molecules of methanol (CH3OH) react with oxygen, they combine with three O2 molecules to form two CO2 molecules and four H2O molecules. How many H2O molecules are formed when 94 methanol molecules react
Answer:
188
Explanation:
For every 2 molecules of methanol reacted, 4 molecules of water are formed. Use this relationship to solve.
2/4 = 94/x
2x = 376
x = 188
188 molecules of water will be formed.
The adiabatic saturation and wet-bulb temperatures will be equivalent for atmospheric air when the two are approximately equal at atmospheric temperatures and pressure.
a. True
b. False
A radioactive isotope of mercury, 197Hg, decays togold, 197Au, with a disintegration constant of 0.0108 h-1. What fraction of a sample will remain at the end of three half-lives (
Answer:
THE FRACTION OF THE SAMPLE REMAINING AFTER THREE HALF LIVES IS 0.125 OR 125/1000
Explanation:
A radioactive isotope of mercury decay to gold with a disintegration constant of 0.0108 h^-1
To calculate the fraction of sample remaining after three half life, we first calculate the half life of the decay.
Half life = ln 2 / Y
Y = disintegration constant
So therefore,
half life = ln 2 / 0.0108
half life = 0.693 / 0.0108
half life = 64.18 hours.
So a decay occurs after 64.18 hours.
To calculate the fraction remaining after 3 half life:
N(t) = N(o) e ^-Yt
where t = 3 half life
So, N / No = e^-Y ( 3 t1/2)
Since t 1/2 = ln 2 / Y, so we can re-write the formula as:
Nt / No = e^-Y ( 3 ln 2/ Y)
Nt / No = e^-3 ln2
Nt / No = e^-3 * 0.693
Nt / No = e^-2.079
Nt / No = 0.125
So the fraction of the sample remaining after 3 half lives is 125/ 1000 or 0.125
g If you have three identical containers (same volume) at the same temperature and pressure, each with a different gas. Container A has He, container B has Ne, and container C has O2. Which flask contains the largest number of molecules? Group of answer choices
Answer:
The three gases, in the three identical containers, will all have the same number of molecules
Explanation:
If these three gases (Helium He, Neon Ne, and Oxygen [tex]O_{2}[/tex]) are all contained in separate identical containers with the same volume. And they are all stored at the same temperature, and pressure. Then, they'll all contain the same number of molecules. This is in line with Avogadro's law which states that "Equal volume of all gases, at the same temperature and pressure, have the same number of molecules."
Heating carvone with aqueous sulfuric acid converts it into carvacrol. The mechanism involves the following steps:
1. The terminal alkene of carvone reacts with acid to form tertiary carbocation 1;
2. A hydride shift results in the formation of tertiary carbocation 2;
3. Deprotonation of the ring leads to conjugated diene 3;
4. Deprotonation at the α carbon leads to the product carvacrol.
Required:
Draw the mechanism and then draw the structure of tertiary carbocation 2.
Answer:
See figure 1
Explanation:
In this question, we have to start with the protonation of the double bond. In carvone we have two double bonds, so, we have to decide first which one would be protonated.
The problem states that the terminal alkene is the one that would is protonated. Therefore, we have to do the protonation in the double bond at the bottom to produce the carbocation number 1. Then, a hydride shift takes place to produce the carbocation number 2. A continuation, an elimination reaction takes place to produce the conjugated diene. Then the diene is protonated at the carbonyl group and with an elimination reaction of an hydrogen in the alpha carbon we can obtain carvacol.
Which resulted from the study of chemistry?
A) Alchemy to turn base metals into noble metals
B) The understanding of earth, air, fire, and water as the basic components of matter.
C) A supernatural, mystical view of the world.
D) Discovering the role of oxygen in combustion
2HCl(aq) + Ba(OH)2(aq) → BaCl2(aq) + 2H2O(l) ΔH = –118 kJ Calculate the heat when 250.0 mL of 0.500 M HCl is mixed 500.0 mL of 0.500 M Ba(OH)2. Assuming that the temperature of both solutions was initially 25.0 oC and that the final mixture has mass of 750.0 g and a specific heat capacity of 4.18 J oC–1g–1, calculate the final temperature (in oC) of the mixture.
Answer:
Heat = 7375J
Final temperature of the mixture = 27.35°C
Explanation:
In the reaction:
2HCl(aq) + Ba(OH)₂(aq) → BaCl₂(aq) + 2H₂O(l) ΔH = –118 kJ
When 2 moles of HCl reacts with excess of Ba(OH)₂ there are released 118kJ.
In the reaction, moles of HCl and Ba(OH)₂ that reacts are:
Moles HCl = 0.250L ₓ (0.500 moles / L) = 0.125 moles HCl
Moles Ba(OH)₂ = 0.500L ₓ (0.500 moles / L) = 0.250 moles Ba(OH)₂
For a complete reaction of 0.125 moles of HCl you need:
0.125 mol HCl ₓ (1 mole Ba(OH)₂ / 2 moles HCl) = 0.0625 moles Ba(OH)₂
As you have 0.250 moles of Ba(OH)₂, this reactant is in excess
2 moles of HCl that react release 118kJ, 0.125 moles of HCl release:
0.125 moles HCl ₓ (118kJ / 2 moles) = 7.375kJ =
7375JThe heat released can be obtained with the formula:
Q = C×m×ΔT
Where Q is heat, C specific heat of the solution, m its mass and ΔT change in temperature.
Replacing:
Q = C×m×ΔT
7375J = 4.18J/g°C×750.0g×ΔT
2.35°C = ΔT
As ΔT = Final T - Initial T:
2.35°C = Final T - 25.0°C
27.35°C = Final temperature of the mixture
Copper was one of the earliest metals used by humans, because it can be prepared from a wide variety of copper minerals, such as cuprite (Cu2O), chalcocite (Cu2S), and malachite [Cu2CO3(OH)2]. Balance the following reactions for converting these minerals into copper metal. Place a coefficient in each gray box.
(a) Cu2O(s) + C(s) rightarrow Cu(s) + CO2(g)
(b) Cu2O(s) + Cu2 S(s) rightarrow Cu(s) + SO2(g)
(c) Cu2 CO3 (OH)2(s) rightarrow CuO(s) + CO2(g) + H2O(g)
Use the left and rightarrow keys to move the cursor out of a superscript or subscript in the module.
Answer:
a. 2 Cu₂O(s) + C(s) → 4Cu(s) + CO₂(g)
b. 2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g)
c. Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)
Explanation:
A reaction is balanced when you have the same amount of atoms in reactants and products.
In the reactions:
(a) Cu₂O(s) + C(s) → Cu(s) + CO₂(g)
As a general rule, you first balance oxygen and hydrogen. In products you have 2 oxygens, then:
2 Cu₂O(s) + C(s) → Cu(s) + CO₂(g)
Carbon is balanced yet. Thus, you need just to balance Cu:
2 Cu₂O(s) + C(s) → 4Cu(s) + CO₂(g)
(b) Cu₂O(s) + Cu₂S(s) → Cu(s) + SO₂(g)
Balancing oxygen:
2Cu₂O(s) + Cu₂S(s) → Cu(s) + SO₂(g)
Sulfur is balanced yet. Now you just need to balance Cu:
2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g)
(c) Cu₂CO₃(OH)₂(s) → CuO(s) + CO₂(g) + H₂O(g)
This reaction is different because the reactant is a chemical with a lot of atoms. we will first balance Cu:
Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)
Balancing copper, oxygen, hydrogen and carbon are balanced:
Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)
The decomposition of hydrogen peroxide to form water and oxygen gas releases 196.6 kJ per mole of hydrogen peroxide. This reaction occurs when hydrogen peroxide is placed on a cut to sterilize it. How much heat is released when 5.70 mol H2O2 decompose
Answer:
1120.62 kJ
Explanation:
In order to find how much heat is released for 7.70 mol, we have to compare it with the heat released from one mole.
So from the question, we have;
196.6 kJ = 1 mol
x = 5.70
x = 5.70 * 196.6 / 1
x = 1120.62 kJ
Which of the following statements is true? a) The rate constant does not depend on the activation energy for a reaction where the products are lower than the reactants. b) A catalyst raises the activation energy of a reaction. c) Rate constants are temperature dependent.
Answer:
Rate constants are temperature dependent.
Explanation:
Reaction rate is used to quantify the rate of chemical reaction. There is a relationship between the reaction rate and the half-life of the reaction and the Gibbs free energy of activation, and the reaction rate is temperature dependent according to the equation.
For a reaction shown below
a A + b B ⇒ c C
The rate of reaction of the reaction is given by
[tex]r = k(T) [A]^{m}[B]^{n}[/tex]
where k(T) is the reaction constant, which is seen to be dependent on the temperature of the reaction.
Also, k(T) is numerically equal to
[tex]k(T) = Ae^{\frac{E_{a} }{RT} }[/tex]
where
r = reaction rate
A = pre exponential factor
[tex]E_{a}[/tex] = Activation energy
R = gas constant
T = temperature
and m and n are experimentally determined partial orders in [A] and [B]
All of the following reactions can be described as displacement reactions except:____________.
a.) Zn(s) + FeCl2(aq) → ZnCl2(aq) + Fe(s).
b.) C6H6(l) + Cl2(g) → C6H5Cl(l) + HCl(g).
c.) 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g).
d.) Cu(s) + 2AgNO3(aq) → Cu(NO3)2(aq) + 2Ag(s).
e.) CuSO4(aq) + Fe(s) → Cu(s) + FeSO4(aq).
Answer:
b
Explanation:
The reaction that is not a displacement reaction from all the options is [tex]C_6H_6_{(l)} + Cl_{2(g)} --> C_6H_5Cl_{(l)} + HCl_{(g)}[/tex]
In a displacement reaction, a part of one of the reactants is replaced by another reactant. In single displacement reactions, one of the reactants completely displaces and replaces part of another reactant. In double displacement reaction, cations and anions in the reactants switch partners to form products.
Options a, c, d, and e involves the displacement of a part of one of the reactants by another reactant while option b does not.
Correct option = b.
The reaction given in Option A is not a displacement reaction. In Displacement reaction functional group of one reactant is replaced by the functional group of the another reactant.
Displacement reaction:
In this reaction functional group of one reactant is replaced by the functional group of the another reactant.
[tex]\bold { Zn(s) + FeCl_2(aq) \rightarrow ZnCl_2(aq) + Fe(s).}[/tex]
In the above reaction Zinc does not any functional group to exchange with iron chloride.
Therefore, the reaction given in Option A is not a displacement reaction.
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One of these has a negative value for (triangle) H. select the correct one
Answer:
The methane gas burns
Explanation:
The burning of methane gas is a combustion reaction. Combustion is an exothermic process. For all exothermic processes, ∆H is negative.
Combustion reaction involves the evolution of heat. The energy of reactants is greater than the energy of products hence the excess energy is given off in the form of heat leading to a negative value of the enthalpy of reaction, hence the answer.
what energy is required for a reaction to occur?
Answer:
activation energy
Explanation:
Answer:
Activation Energy
Explanation:
Activation Energy is the energy required for a reaction to occur.
A compound has two elements, A and B with electronegativities of 0.8 and 3.0 respectively. If the compound has a formula of A2B, which statement describes the bonding best? Group of answer choices The compound is largely ionic with A as the anion. The AB bond is largely covalent with a δ- on A. The compound is largely ionic with A as the cation. The AB bond is largely covalent with a δ+ on A.
Answer:
The compound is largely ionic with A as the cation.
Explanation:
A chemical bond is usually formed between two or more elements. A chemical bond may be ionic, covalent or polar covalent depending on the electro negativity difference between the atoms in the bond.
A large electro negativity difference usually implies an ionic bond. As a rule, when the electronegativity difference is greater than 2.0, the bond is considered ionic.
For the compound A2B, the electro negativity difference between the two atoms is about 2.2. This implies that A2B must be an ionic compound in which A is the cation and B is the anion.
Molarity of NaOH: From the following data calculate molarity of NaOH. Molar mass of KHP is 204.23 g/mol. Show calculation. Mass of Erlenmeyer flask + KHP 84.847 g Mass of Erlenmeyer flask 84.347 g Mass of KHP ??? Final buret reading 12.25 mL Initial buret reading 0.50 mL Volume of NaOH added ???
Answer:
Explanation:
Mass of Erlenmeyer flask + KHP = 84.847 g
Mass of Erlenmeyer flask = 84.347 g
Mass of KHP = .5 g
moles of KHP = .5 / 204.23
= 2.448 x 10⁻³ moles
moles of NaOH reacted = 2.448 x 10⁻³
Final buret reading = 12.25 mL
Initial buret reading = 0.50 mL
Volume of NaOH added=
A sample of N2(g) was collected over water at 25 oC and 730 torr in a container with a volume of 340 mL. The vapor pressure of water at 25 oC is 23.76 torr. What mass of N2 was collected
Answer:
0.36 g of N2.
Explanation:
The following data were obtained from the question:
Temperature (T) = 25 °C
Volume (V) = 340 mL
Measured pressure = 730 torr
Vapour pressure = 23.76 torr
Mass of N2 =..?
First, we shall determine the true pressure of N2. This can be obtained as follow:
Measured pressure = 730 torr
Vapor pressure = 23.76 torr
True pressure =..?
True pressure = measured pressure – vapor pressure
True pressure = 730 – 23.76
True pressure = 706.24 torr.
Converting 706.24 torr to atm, we have:
760 torr = 1 atm
Therefore,
706.24 torr = 706.24 / 760 = 0.929 atm
Next, we shall convert 340 mL to L. This is illustrated below:
1000 mL = 1 L
Therefore,
340 mL = 340/1000 = 0.34 L
Next, we shall convert 25 °C to Kelvin temperature. This is illustrated below:
Temperature (K) = Temperature (°C) + 273
T(K) = T (°C) + 273
T (°C) = 25 °C
T(K) = 25 °C + 273
T (K) = 298 K
Next, we shall determine the number of mole of N2. This can be obtained as follow:
Pressure (P) = 0.929 atm
Volume (V) = 0.34 L
Temperature (T) = 298 K
Gas constant (R) = 0.0821 atm.L/Kmol
Number of mole (n) =...?
PV = nRT
0.929 x 0.34 = n x 0.0821 x 298
Divide both side by 0.0821 x 298
n = (0.929 x 0.34 ) /(0.0821 x 298)
n = 0.0129 mole
Finally, we shall determine the mass of N2 as shown below:
Mole of N2 = 0.0129 mole
Molar mass of N2 = 2x14 = 28 g/mol
Mass of N2 =.?
Mole = mass /Molar mass
0.0129 = mass of N2/ 28
Cross multiply
Mass of N2 = 0.0129 x 28
Mass of N2 = 0.36 g
Therefore, 0.36 g of N2 was collected.
1. Define the Law of Conservation of Mass (via text). Now that you’ve defined this law, explain what it means in your own words using an example.
Explanation:
The law of conservation of mass states that mass can neither be created nor be destroyed.
Explanation in own words = this means that in this universe no one can create or destroy mass.
No physical or chemical force.
what is the balanced equation when copper metal is placed in a solution when platnium ii chloride is placed. what is the equation
Answer:
[tex]Cu~+~PtCl_2->Pt~+~CuCl_2[/tex]
Explanation:
In this case, we can start with the formula of Platinum (II) Chloride. The cation is the atom at the left of the name (in this case [tex]Pt^+^2[/tex]) and the anion is the atom at the right of the name (in this case [tex]Cl^-[/tex]). With this in mind, the formula would be [tex]PtCl_2[/tex].
Now, if we used metallic copper we have to put in the reaction only the copper atom symbol [tex]Cu[/tex]. So, we have as reagents:
[tex]Cu~+~PtCl_2->[/tex]
The question now is: What would be the products? To answer this, we have to remember "single displacement reactions". With a general reaction:
[tex]A~+~BC->AB~+~C[/tex]
With this in mind, the reaction would be:
[tex]Cu~+~PtCl_2->Pt~+~CuCl_2[/tex]
I hope it helps!
A container is filled with a mixture of helium and oxygen gases. A thermometer in the container indicates that the temperature is 22°C. Which gas molecules have the greater average speed? Group of answer choices
Answer:
Helium
Explanation:
The speed of the molecules in a gas is directly proportional to the temperature of the gas and inversely proportional to molar mass of the gas.
This implies that when the temperature of a sample of gas is increased, the speed of the gas molecules is increased accordingly.
At a given constant temperature, the molar mass of the gas is inversely proportional to its average molecular speed. This means that the greater the molecular mass of the gas the lesser the average speed of its molecules.
Oxygen has a greater molecular mass than helium hence it will have a lesser average molecular speed compared to helium.
The gas molecule which has the greater average speed is: Helium molecules because they are less massive.
Given the following data:
Temperature = 22°CAccording to the kinetic-molecular theory, the average speed of gas molecules (particles) is highly dependent on temperature and the molar mass of a gas.
This ultimately implies that, the average speed of gas molecules (particles) is directly proportional to the absolute temperature of an ideal gas and inversely proportional to molar mass of the gas.
Molar mass of Helium gas = 4.0 g/mol.Molar mass of Oxygen gas = 32.0 g/molAt a constant temperature, the higher the molar mass of a gas, the lower would be its average speed and vice-versa.
Hence, helium molecules would have the greater average speed at a constant temperature of 22°C because it is less massive and has a lower molar mass in comparison with oxygen gas.
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Which of these substances has the highest pOH? 0.10 M HCl, pH = 1 0.001 M HNO3, pH = 3 0.01 M NaOH, pH = 12 The answer is 0.10 M HCI, pH=1
Answer:On these combined scales of pH and pH it can be shown that because for water when pH = pH = 7 that pH + pH = 14. This relationship is useful in the inter conversion of values. For example, the pH at a 0.01 M solution of sodium hydroxide is 2, the pH of the same solution must be 14-2 = 12.
Explanation:
The 0.10M HCI, pH = 1 solution has the highest pOH. Therefore, option (1) is correct.
What is the pOH?pOH of a solution can be determined from the negative logarithm of the hydroxide ions concentration in the solution.
The mathematically pOH of the solution can be expressed as:
pOH = -log [OH⁻] ..............(1)
Where [OH⁻] represents the concentration of hydroxide ions in an aqueous solution.
Given, the pH = 1 of HCl
pH + pOH = 14
1 + pOH = 14
pOH = 14 - 1
pOH = 13
Given, the pH = 3 of HNO₃
pH + pOH = 14
3 + pOH = 14
pOH = 14 - 3
pOH = 11
Given, the pH = 12 of NaOH = 0.01 M
pH + pOH = 14
12 + pOH = 14
pOH = 14 - 12
pOH = 2
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what are the similarities between amorphous solid and crystalline solid
Answer:
solid dont know
Explanation:
so sorry ask another
If a bottle of olive oil contains 1.2 kg of olive oil, what is the volume, in milliliters (mL), of the olive oil?
Answer:
1.3 mL
Explanation:
First, get the density of the olive oil, which is 0.917 kg/mL. Then divide the mass by the density:
1.2kg/0.917kg/mL= 1.3086150491 mL. The kg cancel out, leaving us with mL.
It should have 2 significant figures, because 1.2kg has 2 and we are dividing.
The volume of olive oil will be nearly 1300mL or 1.30 L as per the given data.
What is volume?Volume is a measurement of three-dimensional space that is occupied. It is frequently numerically quantified using SI derived units or various imperial units. The definition of length is linked to the definition of volume.
Volume is, at its most basic, a measure of space. The units liters (L) and milliliters (mL) are used to measure the volume of a liquid, also known as capacity.
This measurement is done with graduated cylinders, beakers, and Erlenmeyer flasks.
Here, it is given that mass of olive oil is 1.2kg.
We know that,
Density of olive oil = 0.917kg/l.
Volume = mass/density
Volume = 1.2/0.917.
Volume = 1.30 lit.
Volume = 1300mL.
Thus, the volume of olive oil will be 1300 mL.
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Calculate the concentration of H3O+ in a solution that contains 6.25 × 10-9 M OH- at 25°C. Identify the solution as acidic, basic, or neutral.
Answer:
[OH⁻] = 1.60 × 10⁻⁶ M
Basic
Explanation:
Step 1: Given data
Concentration of H₃O⁺: 6.25 × 10⁻⁹ M
Step 2: Calculate the concentration of OH⁻
We will use the following expression.
Kw = [H₃O⁺] × [OH⁻] = 1.00 × 10⁻¹⁴
[OH⁻] = 1.00 × 10⁻¹⁴ / 6.25 × 10⁻⁹ = 1.60 × 10⁻⁶ M
Step 3: Calculate the pH
We will use the following expresion.
pH = -log [H₃O⁺] = -log (6.25 × 10⁻⁹) = 8.20
Since the pH > 7, the solution is basic.
can I get some urgent help please?
Answer:
hi here goes your answer
Explanation:
iv. The lower the PH, the weaker the base
Why was it important to establish the Clean Air Act?
Answer: The Clean Air Act was important because it emphasized cost-effective methods to protect the air; encouraged people to study the effects of dirty air on human health; and created a regulation that makes any activities that pollute the air illegal.
Explanation:
Answer:
Clean Air Act (CAA), U.S. federal law, passed in 1970 and later amended, to prevent air pollution and thereby protect the ozone layer and promote public health. The Clean Air Act (CAA) gave the federal Environmental Protection Agency (EPA) the power it needed to take effective action to fight environmental pollution.
The blending of one s atomic orbital and three p atomic orbitals produces ________.
A three sp3
B four sp3
C three sp
D four sp2
E four sp
Answer:
B. four sp3
Hope that helps.
We have that for the Question "The blending of one s atomic orbital and three p atomic orbitals produces?"
Answer:
Option B = four [tex]sp^3[/tex]
Explanation:
When 1 s orbital blends with 3 p orbitals, they form a tetrahedrical shaped figure with each being a [tex]SP^3[/tex] orbital.. A total of 4 orbitals
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Why is it important that the primary standard chemical be non-hygroscopic and pure? Why is it important to dry the primary standard to a constant weight?
Answer:
It is extremely important for the primary standard chemical to be non – hygroscopic and pure and to also have a constant weight because you don't want any moisture or any impurities to alter the stoichiometric point in the reaction
It is important that the primary standard chemical be non-hygroscopic and pure to calculate the exact calculation of the reaction.
What is non hygroscopic chemicals?Non hygroscopic chemicals are those compounds which will not absorb water or mositure from the outside.
If we take any substance which are hygroscopic in nature and during the chemical reaction if they absorb water content or moisture then the mass of that substance will alter and changes all the calculation of the reaction.
So, to maintain the stability of calculation we use non hygroscopic materials.
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14. Based on your previous observations, predict the impact of changing the number of moles of a gas sample on the volume of the gas sample (if pressure and temperature are held constant). What effect would changing the number of moles of a gas sample have on the temperature of a gas sample (if pressure and volume are held constant)? Explain
Answer:
Number of moles of gas is directly proportional to the volume of the gas
Number of moles of the gas is directly proportional to the temperature of the gas
Explanation:
According to Avogadro's law, changing the number of moles of a gas changing the volume of the gas also since the volume of a gas is directly proportional to the number of moles of the gas.
Hence from Avogadro's law; V= kn where k is a proportionality constant, V is the volume of the gas and n is the number of moles of the gas.
Changing the number of moles will also lead to a change in the temperature of the gas, since volume is directly proportional to the number of moles of the gas and volume is also directly proportional to temperature (Charles law), it the follows that number of moles of the gas is directly proportional to its temperature.
A cell was prepared by dipping a Cu wire and a saturated calomel electrode into 0.10 M CuSO4 solution. The Cu wire was attached to the positive terminal of a potentiometer and the calomel electrode was attached to the negative terminal.(a) Write a half-reaction for the Cu electrode. (Use the lowest possible coefficients. Omit states-of-matter.)
(c) Calculate the cell voltage.
Answer:
(a) Cu²⁺ +2e⁻ ⇌ Cu
(c) 0.07 V
Explanation:
(a) Cu half-reaction
Cu²⁺ + 2e⁻ ⇌ Cu
(c) Cell voltage
The standard reduction potentials for the half-reactions are+
E°/V
Cu²⁺ + 2e⁻ ⇌ Cu; 0.34
Hg₂Cl₂ + 2e⁻ ⇌ 2Hg + 2Cl⁻; 0.241
The equation for the cell reaction is
E°/V
Cu²⁺(0.1 mol·L⁻¹) + 2e⁻ ⇌ Cu; 0.34
2Hg + 2Cl⁻ ⇌ Hg₂Cl₂ + 2e⁻; -0.241
Cu²⁺(0.1 mol·L⁻¹) + 2Hg + 2Cl⁻ ⇌ Cu + Hg₂Cl₂; 0.10
The concentration is not 1 mol·L⁻¹, so we must use the Nernst equation
(ii) Calculations:
T = 25 + 273.15 = 298.15 K
[tex]Q = \dfrac{\text{[Cl}^{-}]^{2}}{ \text{[Cu}^{2+}]} = \dfrac{1}{0.1} = 10\\\\E = 0.10 - \left (\dfrac{8.314 \times 298.15 }{2 \times 96485}\right ) \ln(10)\\\\=0.010 -0.01285 \times 2.3 = 0.10 - 0.03 = \textbf{0.07 V}\\\text{The cell potential is }\large\boxed{\textbf{0.07 V}}[/tex]