The temperature for each solution is carried out at approximately 297 K where K

ID: 480137 • Letter: T

Question

The temperature for each solution is carried out at approximately 297 K where Kw=1.00×1014.

Part A

0.45 g of hydrogen chloride (HCl) is dissolved in water to make 8.0 L of solution. What is the pH of the resulting hydrochloric acid solution?

Express the pH numerically to two decimal places.

Part B

0.10 g of sodium hydroxide (NaOH) pellets are dissolved in water to make 3.5 L of solution. What is the pH of this solution?

Express the pH numerically to two decimal places

Part C

Determine the pH a solution that is 5.7×102 M in HBr and 1.8×102 M in HNO3

Express your answer to two decimal places.

pH =

A) first calculate the molarity of the solution

M = n/V

n = 0.45 / 36.5 = 0.0123

M = 0.0123 / 8.0 = 1.54 x 10-3 M

pH = - log [H+] = - log [1.54 x 10-3]

pH = 2.81

B) Molarity = n /V

n = 0.1 / 40 = 0.0025

Molarity = 0.0025 / 3.5 = 7.14 x 10-4

pOH = - log [OH-] = -log [7.14 x 10-4] = 3.15

pH = 14 - 3.15

pH = 10.85

C) first [HBr] = [H+] = 5.7 x 10-2M

[HNO3] = [H+] = 1.8 x 10-2 M

total [H+] = (5.7 x 10-2) + (1.8 x 10-2) = 0.075 M

pH = - log [H+] = -log [0.075]

pH = 1.12

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