Stoichiometry question

Question

what mass of KCl will be produced if 4.5g of Cl2 reacts with K?

Answer 1

First, write the correctly balanced equation:

2K + Cl₂ ==> 2KCl

Next, convert 4.5 g Cl₂ to moles Cl₂

4.5 g Cl₂ x 1 mol Cl₂ / 70.9 g = 0.0635 moles Cl₂

Next, calculate moles of KCl formed:

0.064 mols Cl₂ x 2 mols KCl / 1 mol Cl₂ = 0.127 moles KCl

Finally, convert this to grams:

0.127 moles KCl x 74.55 g KCl / mol = 9.5 g KCl (to 2 sig. figs.)

Answer 2

2K + Cl₂ → 2KCl

no. of moles of Cl2 = given mass of Cl2/molar mass of Cl2

= 4.5 g/70.90 g/mol

= 0.06 mol

1 mole of Cl2 produces 2 moles of KCl

Therefore,

no. of moles of KCl = mass of produced KCl/molar mass of KCl

0.06*2 = mass of produced KCl/74.55 g/mol

mass of produced KCl = 0.12 moles*74.55 g/mol

= 9.46 g (Answer)