Question

For each calculations calculate the pH of the solution and the number of moles.

a) [H3O+]= 1.1(10^-3)M; V= 245 mL

b) [H3O+]= 6.0(10^-11)M; V= 105 mL

Answer 1

Answer – a) Given, [H₃O⁺]= 1.1*10^-3 M , volume = 245 mL

We know , pH = -log [H₃O⁺]

                        = -log 1.1*10^-3 M

                        = 2.96

Moles of H₃O⁺ - We know molarity means mole per liter

So, molarity = moles / L

So, moles = molarity * volume (L)

                 = 1.1*10^-3 M * 0.245 L

                 = 0.000270 moles

b) Given, [H₃O⁺]= 6.0*10^-11 M , volume = 105 mL

We know , pH = -log [H₃O⁺]

                        = -log 1.1*10^-3 M

                        = 10.22

Moles of H₃O⁺ - We know molarity means mole per liter

So, molarity = moles / L

So, moles = molarity * volume (L)

                 = 6.0*10^-11 M * 0.105 L

                 = 6.3*10^-12 moles