Question

Complete the following table. (All solutions are at 25 ∘C.)

[H3O+]	[OH−]	pH	Acidic or Basic
3.5×10−3	_____	_____	_____
_____	3.8×10−7	_____	_____
1.8×10−9	_____	_____	_____
_____	_____	7.15	_____

[H3O+]2, [H3O+]4 = [OH−]1, [OH−]3, [OH−]4 = pH1, pH2, pH3, = Complete the fourth column. Enter your answers separated by commas.

Answer 1

basic rules:

Kw = [H+][OH-] = 10^-14

pOH = -log(OH)

pH = -log(H)

14 = pH + pOH

then

a)

H = 3.5*10^-3

pH = -log(H) = -log(3.5*10^-3) = 2.4559

pOH =14-pH = 14-2.4559 = 11.5441

OH = 10^-pOH = 10^-11.5441 = 2.85693*10^-12

b)

[OH-] = 3.8*10^-8

pOH = -log(3.8*10^-8) = 7.420

pH = 14-pOH =14-7.420= 6.58

[H+] = 10^-pH = 10^-6.58 = 2.6302*10^-7

c)

[H+]= 1.8*10^-9

pH = -log(H) = -log(1.8*10^-9) = 8.7447

pOH =14-pH = 14-8.74479 = 5.25521

OH = 10^-pOH = 10^-5.25521=0.00000555635

finally

d)

pH = 7.15

[H+] = 10^-pH = 10^-7.15 = 7.07945*10^-8

pOH= 14-7.15= 6.85

[OH-] = 10^-pOH = 10^-6.85 = 1.4125*10^-7