Answer:
a. 1.7 × 10⁻⁴ mol·L⁻¹; b. 5.5 × 10⁻⁹ mol·L⁻¹
c. 2.3 × 10⁻⁴ mol·L⁻¹; 5.5 × 10⁻⁸ mol·L⁻¹
Explanation:
a. Silver iodate
Let s = the molar solubility.
AgIO₃(s) ⇌ Ag⁺(aq) + IO₃⁻(aq); Ksp = 3.0 × 10⁻⁸
E/mol·L⁻¹: s s
![K_{sp} =\text{[Ag$^{+}$][IO$_{3}$$^{-}$]} = s\times s = s^{2} = 3.0\times 10^{-8}\\s = \sqrt{3.0\times 10^{-8}} \text{ mol/L} = 1.7 \times 10^{-4} \text{ mol/L}](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%5Ctext%7B%5BAg%24%5E%7B%2B%7D%24%5D%5BIO%24_%7B3%7D%24%24%5E%7B-%7D%24%5D%7D%20%3D%20s%5Ctimes%20s%20%3D%20%20s%5E%7B2%7D%20%3D%203.0%5Ctimes%2010%5E%7B-8%7D%5C%5Cs%20%3D%20%5Csqrt%7B3.0%5Ctimes%2010%5E%7B-8%7D%7D%20%5Ctext%7B%20mol%2FL%7D%20%3D%201.7%20%5Ctimes%2010%5E%7B-4%7D%20%5Ctext%7B%20mol%2FL%7D)
b. Barium sulfate
BaSO₄(s) ⇌ Ba²⁺(aq) + SO₄²⁻(aq); Ksp = 1.1 × 10⁻¹⁰
I/mol·L⁻¹: 0.02 0
C/mol·L⁻¹: +s +s
E/mol·L⁻¹: 0.02 + s s
![K_{sp} =\text{[Ba$^{2+}$][SO$_{4}$$^{2-}$]} = (0.02 + s) \times s \approx 0.02s = 1.1\times 10^{-10}\\s = \dfrac{1.1\times 10^{-10}}{0.02} \text{ mol/L} = 5.5 \times 10^{-9} \text{ mol/L}](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%5Ctext%7B%5BBa%24%5E%7B2%2B%7D%24%5D%5BSO%24_%7B4%7D%24%24%5E%7B2-%7D%24%5D%7D%20%3D%20%280.02%20%2B%20s%29%20%5Ctimes%20s%20%5Capprox%20%200.02s%20%3D%201.1%5Ctimes%2010%5E%7B-10%7D%5C%5Cs%20%3D%20%5Cdfrac%7B1.1%5Ctimes%2010%5E%7B-10%7D%7D%7B0.02%7D%20%5Ctext%7B%20mol%2FL%7D%20%3D%205.5%20%5Ctimes%2010%5E%7B-9%7D%20%5Ctext%7B%20mol%2FL%7D)
c. Using ionic strength and activities
(i) Calculate the ionic strength of 0.02 mol·L⁻¹ Ba(NO₃)₂
The formula for ionic strength is
![\mu = \dfrac{1}{2} \sum_{i} {c_{i}z_{i}^{2}}\\\\\mu = \dfrac{1}{2} (\text{[Ba$^{2+}$]}\cdot (2+)^{2} + \text{[NO$_{3}$$^{-}$]}\times(-1)^{2}) = \dfrac{1}{2} (\text{0.02}\times 4 + \text{0.04}\times1)= \dfrac{1}{2} (0.08 + 0.04)\\\\= \dfrac{1}{2} \times0.12 = 0.06](https://tex.z-dn.net/?f=%5Cmu%20%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%5Csum_%7Bi%7D%20%7Bc_%7Bi%7Dz_%7Bi%7D%5E%7B2%7D%7D%5C%5C%5C%5C%5Cmu%20%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%28%5Ctext%7B%5BBa%24%5E%7B2%2B%7D%24%5D%7D%5Ccdot%20%282%2B%29%5E%7B2%7D%20%2B%20%5Ctext%7B%5BNO%24_%7B3%7D%24%24%5E%7B-%7D%24%5D%7D%5Ctimes%28-1%29%5E%7B2%7D%29%20%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%28%5Ctext%7B0.02%7D%5Ctimes%204%20%2B%20%5Ctext%7B0.04%7D%5Ctimes1%29%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%280.08%20%2B%200.04%29%5C%5C%5C%5C%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%5Ctimes0.12%20%3D%200.06)
(ii) Silver iodate
a. Calculate the activity coefficients of the ions

b. Calculate the solubility
AgIO₃(s) ⇌ Ag⁺(aq) + IO₃⁻(aq)
![K_{sp} =\text{[Ag$^{+}$]$\gamma_{Ag^{+}}$[IO$_{3}$$^{-}$]$\gamma_{IO_{3}^{-}}$} = s\times0.75\times s \times 0.75 =0.56s^{2}= 3.0 \times 10^{-8}\\s^{2} = \dfrac{3.0 \times 10^{-8}}{0.56} = 5.3 \times 10^{-8}\\\\s =2.3 \times 10^{-4}\text{ mol/L}](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%5Ctext%7B%5BAg%24%5E%7B%2B%7D%24%5D%24%5Cgamma_%7BAg%5E%7B%2B%7D%7D%24%5BIO%24_%7B3%7D%24%24%5E%7B-%7D%24%5D%24%5Cgamma_%7BIO_%7B3%7D%5E%7B-%7D%7D%24%7D%20%3D%20s%5Ctimes0.75%5Ctimes%20s%20%5Ctimes%200.75%20%3D0.56s%5E%7B2%7D%3D%203.0%20%5Ctimes%2010%5E%7B-8%7D%5C%5Cs%5E%7B2%7D%20%3D%20%5Cdfrac%7B3.0%20%5Ctimes%2010%5E%7B-8%7D%7D%7B0.56%7D%20%3D%205.3%20%5Ctimes%2010%5E%7B-8%7D%5C%5C%5C%5Cs%20%3D2.3%20%5Ctimes%2010%5E%7B-4%7D%5Ctext%7B%20mol%2FL%7D)
(iii) Barium sulfate
a. Calculate the activity coefficients of the ions

b. Calculate the solubility
BaSO₄(s) ⇌ Ba²⁺(aq) + SO₄²⁻(aq
![K_{sp} =\text{[Ba$^{2+}$]$\gamma_{ Ba^{2+}}$[SO$_{4}$$^{2-}$]$\gamma_{ SO_{4}^{2-}}$} = (0.02 + s) \times 0.32\times s\times 0.32 \approx 0.02\times0.10s\\2.0\times 10^{-3}s = 1.1 \times 10^{-10}\\s = \dfrac{1.1\times 10^{-10}}{2.0 \times 10^{-3}} \text{ mol/L} = 5.5 \times 10^{-8} \text{ mol/L}](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%5Ctext%7B%5BBa%24%5E%7B2%2B%7D%24%5D%24%5Cgamma_%7B%20Ba%5E%7B2%2B%7D%7D%24%5BSO%24_%7B4%7D%24%24%5E%7B2-%7D%24%5D%24%5Cgamma_%7B%20SO_%7B4%7D%5E%7B2-%7D%7D%24%7D%20%3D%20%280.02%20%2B%20s%29%20%5Ctimes%200.32%5Ctimes%20s%5Ctimes%200.32%20%5Capprox%20%200.02%5Ctimes0.10s%5C%5C2.0%5Ctimes%2010%5E%7B-3%7Ds%20%3D%201.1%20%5Ctimes%2010%5E%7B-10%7D%5C%5Cs%20%3D%20%5Cdfrac%7B1.1%5Ctimes%2010%5E%7B-10%7D%7D%7B2.0%20%5Ctimes%2010%5E%7B-3%7D%7D%20%5Ctext%7B%20mol%2FL%7D%20%3D%205.5%20%5Ctimes%2010%5E%7B-8%7D%20%5Ctext%7B%20mol%2FL%7D)
Answer:
pOH = 11.5
[H⁺] = 0.003 M
[OH⁻] = 3 × 10⁻¹² M
Explanation:
The computation is shown below:
Given that
pH = 2.5
Based on the above information
We know that
pH + pOH = 14 ⇒ pOH = 14 - pH
pOH = 14 - 2.5
pOH = 11.5
[H⁺] = 10^(-pH) = 10^(-2.5)
[H⁺] = 0.003 M
[OH⁻] = 10^(-pOH)
= 10^(-11.5)
= 3 × 10⁻¹² M
[OH⁻] = 3 × 10⁻¹² M
Hence, the above represents the answer
Answer:
b. Second order in NO and first order in O₂.
Explanation:
A. The mechanism
![\rm 2NO\xrightarrow[k_{-1}]{k_{1}}N_{2}O_{2} \, (fast)\\\rm N_{2}O_{2} + O_{2}\xrightarrow{k_{2}} 2NO_{2} \, (slow)](https://tex.z-dn.net/?f=%5Crm%202NO%5Cxrightarrow%5Bk_%7B-1%7D%5D%7Bk_%7B1%7D%7DN_%7B2%7DO_%7B2%7D%20%5C%2C%20%28fast%29%5C%5C%5Crm%20N_%7B2%7DO_%7B2%7D%20%2B%20O_%7B2%7D%5Cxrightarrow%7Bk_%7B2%7D%7D%202NO_%7B2%7D%20%5C%2C%20%28slow%29)
B. The rate expressions
![-\dfrac{\text{d[NO]} }{\text{d}t} = k_{1}[\text{NO]}^{2} - k_{-1} [\text{N}_{2}\text{O}_{2}]^{2}\\\\\rm -\dfrac{\text{d[N$_{2}$O$_{2}$]}}{\text{d}t} = -\dfrac{\text{d[O$_{2}$]}}{\text{d}t} = k_{2}[ N_{2}O_{2}][O_{2}] - k_{1} [NO]^{2}\\\\\dfrac{\text{d[NO$_{2}$]}}{\text{d}t}= k_{2}[ N_{2}O_{2}][O_{2}]](https://tex.z-dn.net/?f=-%5Cdfrac%7B%5Ctext%7Bd%5BNO%5D%7D%20%7D%7B%5Ctext%7Bd%7Dt%7D%20%3D%20k_%7B1%7D%5B%5Ctext%7BNO%5D%7D%5E%7B2%7D%20-%20k_%7B-1%7D%20%5B%5Ctext%7BN%7D_%7B2%7D%5Ctext%7BO%7D_%7B2%7D%5D%5E%7B2%7D%5C%5C%5C%5C%5Crm%20-%5Cdfrac%7B%5Ctext%7Bd%5BN%24_%7B2%7D%24O%24_%7B2%7D%24%5D%7D%7D%7B%5Ctext%7Bd%7Dt%7D%20%3D%20-%5Cdfrac%7B%5Ctext%7Bd%5BO%24_%7B2%7D%24%5D%7D%7D%7B%5Ctext%7Bd%7Dt%7D%20%3D%20k_%7B2%7D%5B%20N_%7B2%7DO_%7B2%7D%5D%5BO_%7B2%7D%5D%20-%20k_%7B1%7D%20%5BNO%5D%5E%7B2%7D%5C%5C%5C%5C%5Cdfrac%7B%5Ctext%7Bd%5BNO%24_%7B2%7D%24%5D%7D%7D%7B%5Ctext%7Bd%7Dt%7D%3D%20k_%7B2%7D%5B%20N_%7B2%7DO_%7B2%7D%5D%5BO_%7B2%7D%5D)
The last expression is the rate law for the slow step. However, it contains the intermediate N₂O₂, so it can't be the final answer.
C. Assume the first step is an equilibrium
If the first step is an equilibrium, the rates of the forward and reverse reactions are equal. The equilibrium is only slightly perturbed by the slow leaking away of N₂O₂ to form product.
![\rm k_{1}[NO]^{2} = k_{-1} [N_{2}O_{2}]\\\\\rm [N_{2}O_{2}] = \dfrac{k_{1}}{k_{-1}}[NO]^{2}](https://tex.z-dn.net/?f=%5Crm%20k_%7B1%7D%5BNO%5D%5E%7B2%7D%20%3D%20k_%7B-1%7D%20%5BN_%7B2%7DO_%7B2%7D%5D%5C%5C%5C%5C%5Crm%20%5BN_%7B2%7DO_%7B2%7D%5D%20%3D%20%5Cdfrac%7Bk_%7B1%7D%7D%7Bk_%7B-1%7D%7D%5BNO%5D%5E%7B2%7D)
D. Substitute this concentration into the rate law
![\rm \dfrac{\text{d[NO$_{2}$]}}{\text{d}t}= \dfrac{k_{2}k_{1}}{k_{-1}}[NO]^{2} [O_{2}] = k[NO]^{2} [O_{2}]](https://tex.z-dn.net/?f=%5Crm%20%5Cdfrac%7B%5Ctext%7Bd%5BNO%24_%7B2%7D%24%5D%7D%7D%7B%5Ctext%7Bd%7Dt%7D%3D%20%5Cdfrac%7Bk_%7B2%7Dk_%7B1%7D%7D%7Bk_%7B-1%7D%7D%5BNO%5D%5E%7B2%7D%20%5BO_%7B2%7D%5D%20%3D%20k%5BNO%5D%5E%7B2%7D%20%5BO_%7B2%7D%5D)
The reaction is second order in NO and first order in O₂.