Hydrochloric acid was added to 200 g of a 15% sodium hydroxide solution. Calculate the mass of the salt formed.

Given:

m (NaOH) = 200 g

w% (NaOH) = 15%

To find:

m (salt) -?

Solution:

NaOH + HCl = NaCl + H2O, – we solve the problem based on the composed reaction equation:

1) Find the mass of sodium hydroxide in the solution:

m (NaOH) = 200 g * 0.15 = 30 g

2) Find the amount of sodium hydroxide:

n (NaOH) = m: M = 30 g: 40 g / mol = 0.75 mol

3) We compose a logical expression:

if 1 mol of NaOH gives 1 mol of NaCl,

then 0.75 mol NaOH will give x mol NaCl,

then x = 0.75 mol.

4) Find the mass of sodium chloride formed during the reaction:

m (NaCl) = n * M = 0.75 mol * 58.5 g / mol = 43.875 g.

Answer: m (NaCl) = 43.875 g.