Question

Sodium hydroxide neutralises hydrochloric acid as shown in the equation:

Answer 1

Explanation:

Mole ratio of NaOH : HCl = 1: 1

Moles of NaOH used = 0.1 mol/1000 cm3 × 27.20 cm3

= 2.72 × 10^-3 mol

Therefore moles of HCl used is also 2.72 × 10^-3 mol

So concentration of HCl can be found by dividing the no.of moles of HCl by the volume of HCl as follows

2.72 × 10^-3 mol/ 5cm3

1000cm3 = 1dm3

Therefore,

1cm3 = 1/1000 dm3

5cm3 = 5/1000 dm3

HCl conc. = 2.72 × 10^-3 mol/ 5×10^-3 dm3

= 0.544 moldm-3