Question

find pH - answers and work please

2.6×10⁻² M HI

Express your answer to two decimal places.

pH =

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Part B

0.117 M HClO4

Express your answer to three decimal places.

pH =

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Part C

a solution that is 5.2×10⁻² M in HClO4 and 2.8×10⁻² M in HCl

Express your answer to two decimal places.

pH =

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Part D

a solution that is 1.90% HCl by mass (Assume a density of 1.01 g/mL for the solution.)

Express your answer to three decimal places.

pH =

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Answer 1

A)

pH of 2.6×10−2 M HI

HI --> H+ + I-

so

[H+] = 2.6*10^-2

pH = -log(H) = -log(2.6*10^-2) = 1.585

B)

HClO4 --> H+ + OCl4-

[H+] = 0.117

pH= -log(0.117 ) = 0.9318141

c)

5.2×10−2 M in HClO4 and 2.8×10−2 M in HCl

[H+] from ClO4 = 5.2*10^-2

[H+] from Hcl = 2.8*10^-2

total [H+] = 5.2*10^-2 + 2.8*10^-2 = 0.08 M

D)

assume a volume of 1 Liter so... 1000 mL

mass = D*V = 1.01*1000 = 1010 g of solution

of that, 1.9% is HCl so:

1.9/100*1010 = 19.19 g of HCl

mol = mass/MW = 19.19/36 = 0.5330 mol of HCl

M = mol/V = 0.5330/1 = 0.5330

then

HCl --> H+ + Cl-

so

[Hcl]= 0.5330 = [H+]

pH = -log(H+) = -log(0.5330 = 0.2732

pH = 0.2732