Using Moles to Balance Equations Flashcards

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What are the steps to work out the balancing numbers of an equation from the masses of reactants and products?
e.g. 4.8 g Mg + 3.2 g $\mathrm{O_2}$ → 8.0 g MgO

1. Convert each mass to moles: $4.8/24 = 0.2$, $3.2/32 = 0.1$, $8.0/40 = 0.2$
2. Divide by the smallest to get a whole number ratio: 2 : 1 : 2
3. Write the equation: $2\mathrm{Mg} + \mathrm{O_2} \rightarrow 2\mathrm{MgO}$

How do you turn a set of mole values into simple whole number balancing numbers?
e.g. 0.25 mol : 0.75 mol

Divide them all by the smallest value (then multiply up if needed).
e.g. $0.25 : 0.75$ → 1 : 3

True or false? The balancing numbers of an equation can be found from the ratio of the masses of the reactants and products in grams.

False. The masses must first be converted to amounts in moles, and that ratio simplified.