1) Part A 0.50 g of hydrogen chloride (HCl) is dissolved in water to make 8.0 L

ID: 903988 • Letter: 1

Question

Part A

0.50 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

0.60 g of sodium hydroxide (NaOH) pellets are dissolved in water to make 7.5 L of solution. What is the pH of this solution?

Express the pH numerically to two decimal places.

A certain weak acid, HA, has a Ka value of 8.9×107.

Part A

Calculate the percent ionization of HA in a 0.10 M solution.

Express your answer to two significant figures and include the appropriate units.

Part B

Calculate the percent ionization of HA in a 0.010 M solution.

Express your answer to two significant figures, and include the appropriate units

Part A

molarity = (mass / molar mass ) x 1/ V = (0.50 / 36.5 ) X 1/8 = 1.71 x 10^-3 M

[H+] = 1.71 x 10^-3 M

pH = -log[H+] = -log (1.71 x 10^-3) = 2.77

pH = 2.77

part B)

NaOH molarity = (0.60 / 40 ) x 1/ 7.5 = 2 x 10^-3 M

[OH-] = 2 x 10^-3 M

pOH = -log [OH-] = -log (2 x10^-3) = 2.70

pH + pOH = 14

pH = 11.30

Ka = 8.9×107.

Part A

C= 0.10 M

x = sqrt (Ka /C) = sqrt ( 8.9×107 / 0.1)

x = 2.98×103

percent ionisation % = x % = 2.98 ×10^-3 x 100 = 0.30 %

part B)

x % = sqrt (Ka / C) x 100

= sqrt ( 8.9×10^7 x 0.01) x 100

= 0.0094 %

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