Question

How many moles are there in 1.5 g of ethanol, `CH_3CH_2OH`?

Answer 1

`3.242459724759267mol`

Explanation:

Use the formula
`n = m/M`
where `n` is the amount in moles (`mol`), `m` is the mass in grams (`g`), and `M` is the molar mass in grams per mole (`gmol^-1`).

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To find the molar mass of ethanol:
There are 2 `C` atoms (molar mass `12.011gmol^-1`),
6 `H` atoms (molar mass `1.008gmol^-1`),
and 1 `O` atom (molar mass `15.999gmol^-1`)

`(2 xx 12.011) + (6 xx 1.008) + (1 xx 15.999) = 46.261176gmol^-1`

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To find the amount of ethanol:

`n(CH_3CH_2OH) = (1.5g)/(46.261176gmol^-1)`

`= 3.242459724759267mol`