Question

How do you calculate mass of a known substance (sodium chloride for example) given its amount in terms of moles? O multiply moles by the molar mass O divide moles by the molar mass O cannot be determined based on the given divide the molar mass by the Avogadro's number

Answer 1

1) List the known and unknown quantities.

Amount of substance: moles

mass: grams

2) Set the equation.

`Molar\text{ }Mass=\frac{Mass\text{ }(grams)}{Amount\text{ }of\text{ }substance\text{ }(moles)}`
`Molar\text{ }Mass\ast Amount\text{ }of\text{ }substance\text{ }(moles)=Mass\text{ }(grams)`

If we have the number of moles of a compound, we have to multiply it by the molar mass to find the mass.

Answer: multiply moles by the molar mass.

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