How do you solve empirical formula calculations?

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How do you solve empirical formula calculations?

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Answer 1 · 2016-05-24T11:38:57

The explanation is given below.

Explanation:

Step 1 : Assume percentages as masses contained in a total of 100 grams.

Step 2 : Use $n = \frac{m}{M}$ $n = m /M$ formula to calculate the number of moles in each atom.
$n$ $n$ = number of moles
$m$ $m$ = mass of substance
$M$ $M$ = molar mass

Step 3 : Divide all number of moles by the smallest.

Step 4 : Round them to nearest whole numbers and assign as subscripts.

Example question: Calculate empirical formula of a compound that has $11 %$ $11%$ hydrogen and $89 %$ $89%$ oxygen.

Assume that 100 grams contains $11$ $11$ $g$ $g$ of $H$ $H$ and $89$ $89$ $g$ $g$ of $O$ $O$ .

To move on to step 2, you also need to know the molar mass of $H$ $H$ and $O$ $O$ . In that case, the molar mass of $H$ $H$ is $1.0$ $1.0$ $g$ $g$ / $m o l$ $mol$ and the molar mass of $O$ $O$ is $16.0$ $16.0$ $g$ $g$ / $m o l$ $mol$ .

Now you can find the number of moles for each atom.
$n (H)$ $n(H)$ = $\frac{11}{1.0}$ $11/1.0$ = $11$ $11$ moles
$n (O)$ $n (O)$ = $\frac{89}{16.0}$ $89/16.0$ = $5.6$ $5.6$ moles

Step 3, multiply the number of moles by the smallest.
$H$ $H$ = $\frac{11}{5.6} = 2.00$ $11 / 5.6 = 2.00$
$O = \frac{5.6}{5.6} = 1.00$ $O = 5.6 /5.6= 1.00$
*Has been rounded to nearest whole number

Step 4, assign them as subscripts.
Since there is 2 Hydrogen and and 1 Oxygen, you know that the empirical formula is $H_{2} O$ $H_2O$ .

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How do you solve empirical formula calculations?

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