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IrinaVladis [17]

2 years ago

6

A chemist has 2.0 mol of methanol (CH3OH). The molar mass of methanol is 32.0 g/mol. What is the mass, in grams, of the sample?

16 30 32 64

1 answer:

rodikova [14]2 years ago

3 0

Answer:

$\boxed {\boxed {\sf D. \ 64 \ grams }}$

Explanation:

Given the moles, we are asked to find the mass of a sample.

We know that the molar mass of methanol is 32.0 grams per mole. We can use this number as a fraction or ratio.

$\frac{32 \ g \ CH_3OH}{1 \ mol \ CH_3OH}$

Multiply by the given number of moles, which is 2.0

$2.0 \ mol \ CH_3OH *\frac{32 \ g \ CH_3OH}{1 \ mol \ CH_3OH}$

The moles of methanol will cancel each other out.

$2.0 \ *\frac{32 \ g \ CH_3OH}{1 }$

The denominator of 1 can be ignored.

$2.0 * 32 \ g\ CH_3OH$

Multiply.

$64 \ g \ CH_3OH$

There are 64 grams of methanol in the sample.

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$n = \frac{m}{M}$

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$m$ - Mass of the element, measured in grams.

$M$ - Molar mass of the element, measured in grams per mol.

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$n = \frac{84.067\,g}{12.011\,\frac{g}{mol} }$

$n = 7$

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$n = \frac{6.057\,g}{1.008\,\frac{g}{mol} }$

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$n = \frac{31.995\,g}{15.999\,\frac{g}{mol} }$

$n = 2$

For each mole of organic acid, there are 7 moles of carbon, 6 moles of hydrogen and 2 moles of oxygen. Hence, the molecular formula of the compound is:

$C_{7}H_{6}O_{2}$

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