Question

1) What is the H3O+ concentration to the correct number of significant figures for solutions with the following pH values.

A) 9.0. B) 7.00 C) -0.30. D) 15.18. E) 2.63. F) 10.75

2)calculate the pH and the concentrations of all species present (H3O+, F-, HF, Cl, and OH-) in a solution that contains 0.10 M HF (

Ka= 3.5 * 10^-4 ) and 0.10 M HCl

Answer 1

1)

A)

we have below equation to be used:

pH = -log [H3O+]

9.0 = -log [H3O+]

log [H3O+] = -9

[H3O+] = 10^(-9)

[H3O+] = 1.00*10^-9 M

B)

we have below equation to be used:

pH = -log [H3O+]

7.00 = -log [H3O+]

log [H3O+] = -7

[H3O+] = 10^(-7)

[H3O+] = 1.000*10^-7 M

C)

we have below equation to be used:

pH = -log [H3O+]

-0.3 = -log [H3O+]

log [H3O+] = 0.3

[H3O+] = 10^(0.3)

[H3O+] = 2.0 M

D)

we have below equation to be used:

pH = -log [H3O+]

15.18 = -log [H3O+]

log [H3O+] = -15.18

[H3O+] = 10^(-15.18)

[H3O+] = 6.607*10^-16 M

E)

we have below equation to be used:

pH = -log [H3O+]

2.63 = -log [H3O+]

log [H3O+] = -2.63

[H3O+] = 10^(-2.63)

[H3O+] = 2.344*10^-3 M

F)

we have below equation to be used:

pH = -log [H3O+]

10.75 = -log [H3O+]

log [H3O+] = -10.75

[H3O+] = 10^(-10.75)

[H3O+] = 1.7783*10^-11 M

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