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.