Answer to Question #326235 in General Chemistry for moath

Question

1. Find the pH of the following solutions. Make sure you express your answer in the correct

number of significant digits. (12 marks)

a) 0.0010 M HClO₄ …..__________ b) 2.35 x 10^-3 M KOH …___________

c) 4.678 x 10^-5 M HNO₃..____­_____ d) 12.0 M HCl ...............…__________

e) 0.20 M Ba(OH)₂ .....___________ f) 4.30 M H₃O⁺ ...........…...__________

2. Find the [H₃O⁺] in 0.00256 M HBr. (1 mark)

Answer ________________

3. Find the [H₃O⁺] in 0.80 M LiOH. (2 marks)

Answer ________________

4. Find the [H₃O⁺] in a solution with a pH = 3.216 (1 mark)

Answer ________________

5. Find the [H₃O⁺] in 0.45 M BaO (2 marks)

Answer ________________

6. Find the [OH^-] in 0.150 M HClO₄ (2 marks)

20

Answer ________________

Answer 1

1) a) HClO₄ + H₂O = H₃O⁺ + ClO₄^-

pH = -lg [H₃O⁺] = -lg (0.0010 M) = 3

b) KOH = K⁺ + OH^-

pH = 14 - pOH = 14 - (-lg [OH^-]) = 14 - (-lg(2.35 x 10^-3 M)) = 11.37

c) HNO₃ + H₂O = H₃O⁺ + NO₃^-

pH = -lg [H₃O⁺] = -lg (4.678 x 10^-5 M) = 4.33

d) HCl + H₂O = H₃O⁺ + Cl^-

pH = -lg [H₃O⁺] = -lg (12.0 M) = -1.08

e) Ba(OH)₂ = Ba²⁺ + 2OH^-

pH = 14 - pOH = 14 - (-lg [OH^-]) = 14 - (-lg(2 x 0.20 M)) = 13.6

f) pH = -lg [H₃O⁺] = -lg (4.30 M) = -0.63

2) HBr + H₂O = H₃O⁺ + Br^-

[H₃O⁺] = 0.00256 M

3) LiOH = Li⁺ + OH^-

[H₃O⁺] = 10^-14 / [OH^-] = 10^-14 / 0.80 = 1.25 x 10^-14 M

4) pH = 3.216

[H₃O⁺] = 10^-pH = 10^-3.216 = 6.08 x 10^-4 M

5) O^2- + H₂O = 2OH^-

[OH^-] = 2 x 0.45 = 0.90 M

[H₃O⁺] = 10^-14 / [OH^-] = 10^-14 / 0.90 = 1.11 x 10^-14 M

6) HClO₄ + H₂O = H₃O⁺ + ClO₄^-

[H₃O⁺] = 0.150 M

[OH^-] = 10^-14 / [H₃O⁺] = 10^-14 / 0.150 = 6.67 x 10^-14 M