Question

One part of the problem -solving strategy for empirical formula determination is to base the calculation on 100g of compound. What if you chose a mass other than 100g? Would this work? What if you chose to base the calculation on 100 moles of compound? Would this work?

Short answer

Considering 100 moles of substance as the base will not work.

Step-by-step solution

Empirical formula

The empirical formula of a compound is based on the mass percentages, and we have considered the total mass of the compound as 100g. So, the mass of each element will be equal to the given percent in grams.

Therefore, the number of moles of each element present in 100g of the compound will be determined by dividing the mass of the element by its molar mass.

Then, divide each value of the number of moles by the smallest of the values and then multiply with an integer to get all the values in integer forms.

Compound explanation

Even considering any other mass of the compound, the percentage will remain the same. The values may vary in the first two steps. But, the relative values of the number of moles of the elements remain the same. So, the result of the third step will be the same for any amount of mass considered as base.

Hence, choosing a mass other than 100g will work.

Conclusion

The number of moles is equal to the mass divided by the molar mass of the substance. The molar mass of each element is different from another. If 100 moles of a compound are considered as a base, it is required to convert this value into mass (as mass percentages are given). For that, the molar mass of the substance should be known.

So, directly considering 100 moles of substance as the base will not work.