Question

6.45g of lithium reacts with 9.2g of oxygen gas to produce lithium oxide.How many grams of Li20 are formed? Hint: write the balanced chemical equation first.

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Answer 1

Balanced Equation: 4Li + O2 —> = 2Li2O

Stoichiometry:

Choose a given first.

6.45g Li • 1 mole Li 2 moles Li2O 30 g. Li2O
————- • ———- • ——
7 g Li 4 moles Li** 1 mol. Li2O

** Mole to mole ratio from balanced equation

Multiple everything on top and divide by everything multiplied on bottom.

387
———- = ~ 13.8 g. Li2O
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