Question

3.65% (w/w) HCl is found to have density of 1.4gm/L the molarity of solution is

Answer 1

Step 1 : Calculate mass of 1 litre

1.4 g is mass of 1 ml

Mass of 1000 ml = 1000 × 1.4 = 1400g

Step 2 : Calculate mass of HCl from the given percentage mass.

The HCl is 3.65% by mass.

Mass of HCl is thus :

3.65/100 × 1400g = 51.1g

Step 3 : Calculating moles of HCl

Molar mass of HCl:

35.5 + 1 = 36.5g/mol

Moles = mass / molar mass

51.1 / 36.5 = 1.4 moles.

Step 4 : Calculating Molarity

Molarity = moles / litres of solution

1.4 / 1 L= 1.4 moles per litre

Molarity = 1.4 moles / litre