Question

What mass, in grams, of sodium hydroxide (NaOH) is produced if 20 grams of sodium metal(Na) reacts with excess water?

Answer 1

1. Write the equation and balance it.
2. Convert 20 g Na metal to moles. mols = grams/molar mass.
3. Using the coefficients in the balanced equation, convert moles Na metal to mols NaOH.
4. Now convert moles NaOH to grams. g = moles x molar mass.

Answer 2

2Na + S --> Na2S

20g Na x (1 mole Na)/(23g Na) = 0.87 mol Na

0.87 mole Na x (1 mol Na2S)/(2 mol Na) x (55.1g Na2S)/(1 mol Na2S)

=23.97g Na2S