Question

Measurements show that unknown compound X has the following composition:

Answer 1

Answer: The empirical formula of X is $C_{5}H_4O_2$.

Explanation:

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 62.4 g

Mass of H = 4.19 g

Mass of O = 33.2 g

Step 1 : convert given masses into moles.

Moles of C=$\frac{\text{ given mass of Na}}{\text{ molar mass of Na}}= \frac{62.4g}{12g/mole}=5.2moles$

Moles of H=$\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{4.19g}{1g/mole}=4.19moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{33.2g}{16g/mole}=2.1moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =$\frac{5.2}{2.1}=2.5$

For H =$\frac{4.19}{2.1}=2$

For O =$\frac{2.1}{2.1}=1$

The ratio of C: H: O = 2.5 : 2 : 1

Converting it into simple whole number ratios by multiplying by 2:

Hence the empirical formula of X is $C_{5}H_4O_2$.