# Mass fraction of calcium 29.41%, sulfur 23.53%, oxygen 47.06%. Determine the salt formula, determine its paint mass.

Let us denote: i is the number of calcium atoms, j is the number of sulfur atoms, k is the number of oxygen atoms, M is the molecular weight of the compound.

The relative atomic mass of calcium is 40, sulfur is 32, oxygen is 16.

For mass fractions, we compose the following expressions:

0.2941 = 40i / M;

0.2353 = 32j / M;

0.4706 = 16k / M;

Let us express the molecular weight from the following expressions:

M = 40i / 0.2941 = 136i;

M = 32j / 0.2353 = 136j;

M = 16k / 0.4706 = 34k;

We equate the resulting values: 136i = 136j = 34k. This means that the unknown values of the numbers: i = 1, j = 1, k = 4. The formula of the salt is CaSO4.

Let’s find the molar mass of the salt:

40 + 32 + 16 * 4 = 136 g / mol;

Answer: the formula of the salt is CaSO4 (calcium sulfate), its molar mass is 136 g / mol.