Question

2 NaOH + H2SO4 - 2 H2O + Na2SO4How many moles of sodium hydroxide are needed to form 63 grams of sodium sulfate?

Answer 1

1) Write the chemical equation.

$2NaOH+H_2SO_4\rightarrow2H_2O+Na_2SO_4$

2) Convert the mass of Na2SO4 to moles of Na2SO4.

The molar mass of Na2SO4 is 142.0421 g/mol.

$mol\text{ }Na_2SO_4=63\text{ }g\text{ }Na_2SO_4*\frac{1\text{ }mol\text{ }Na_2SO_4}{142.0421\text{ }g\text{ }Na_2SO_4}=0.4435\text{ }mol\text{ }Na_2SO_4$

3) Moles of NaOH needed

The molar ratio between NaOH and Na2SO4 is 2 mol NaOH: 1 mol Na2SO4.

$mol\text{ }NaOH=0.4435\text{ }mol\text{ }Na_2SO_4*\frac{2\text{ }mol\text{ }NaOH}{1\text{ }mol\text{ }Na_2SO_4}=0.8871\text{ }mol\text{ }NaOH$

0.8871 mol NaOH is required to form 63 g Na2SO4.