m (NaOH) = 200 g
w% (NaOH) = 15%
m (salt) -?
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.
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