PLEASE EXPLAIN HOW TO GET THE ANSWER! THANK YOU 1. Calculate the pH of a solutio
ID: 517633 • Letter: P
Question
PLEASE EXPLAIN HOW TO GET THE ANSWER! THANK YOU
1. Calculate the pH of a solution that is 0.20M NH3(aq) and 0.35 M NH4Cl(aq). (Kb(NH3) = 1.8 x 10-5)
2. . For PbCl2 (Ksp = 2.4 × 10–4), will a precipitate of PbCl2 form when 0.10 L of 6.0 × 10–1 M Pb(NO3)2 is added to 400 mL of 9.0 × 10–1 M NaCl?
A) Yes, because Q > Ksp. .
B) No, because Q < Ksp.
C) No, because Q = Ksp
D) Yes, because Q < Ksp
3. Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 4.6–4.8?
A) CH3COO2Na / CH3COOH (Ka = 1.8 × 10–5)
B) NH3 / NH4Cl (Ka = 5.6 × 10–10)
C) NaOCl / HOCl (Ka = 3.2 × 10–8)
D) NaNO2 / HNO2 (Ka = 4.5 × 10–4) E) NaCl / HCl
4. Which of these species will act as a Lewis acid?
A) NH3
B) NH4 +
C) H2O
D) BF3
E) F–
6.When 4.0 10–2 mole of a weak monoprotic acid is dissolved in 350. mL of water, the pH is 3.05. What is the Ka of the acid?
Explanation / Answer
1)
NH3 and NH4Cl forms a basic buffer
NH3 is base and NH4+ is conjugate acid in this buffer
Kb = 1.8*10^-5
pKb = - log (Kb)
= - log(1.8*10^-5)
= 4.74
use:
pOH = pKb + log {[conjugate acid]/[base]}
= 4.74+ log {0.35/0.2}
= 4.99
use:
pH = 14 - pOH
= 14 - 4.99
= 9.01
Answer: 9.01
I am allowed to answer only 1 question at a time
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