Question

Complete the following table

Solution	[H3O+]	[OH-]	pOH	acidic, basic, neutral
Orange juice
Milk

1

a) Calculations for orange juice

pH= 4.5

b) calculation for milk

pH= 6.0

Answer 1

(1) If pH is inbetween 0 to 7 the solution is acidic & if it is inbetween 7 to 14 then the solution is basic.

If pH = 7 then the solution is neutral.

(2) pH + pOH = 14

So pOH = 14 - pOH

(3) pH = - log [H⁺]            

           So [H⁺] = 10 ^-pH

pOH = - log [OH^-]

                      [OH^-] = 10 ^-pOH

(4) [H⁺] = [H₃O⁺]

a) Calculations for orange juice :

Given pH= 4.5    Since pH is less than 7 so the solution is acidic.

pOH = 14 - pH = 14 - 4.5 = 9.5

           pOH = 9.5

We know that pH = - log [H⁺]

                      [H⁺] = 10 ^-pH

                             = 10 ^-4.5

                             = 3.16x10^-5 M

So [H⁺] = 3.16x10^-5 M

[OH^-] = 10 ^-pOH = 10 ^-9.5 = 3.16 x10^-10 M

So [OH^-] = 3.16 x10^-10 M

b) calculation for milk

Given pH= 6.0    Since pH is less than 7 so the solution is acidic.

pOH = 14 - pH = 14 - 6.0 = 8.0

           pOH = 8.0

We know that pH = - log [H⁺]

                      [H⁺] = 10 ^-pH

                             = 10 ^-6.0

                             = 1.0 x10^-6 M

So [H⁺] = 1.0 x10^-6 M

[OH^-] = 10 ^-pOH = 10 ^-8.0 = 1.0 x10^-8 M

So [OH^-] = 1.0 x10^-8 M