A compound is 36.1% water. After drying off the water, the rest is 40.1% oxygen, 39.8% copper, and 20.1% sulfur.
My crystal ball is hazy today. It isn't telling me what question you are asking.
what is the empirical formula
You didn't ask a question. I suppose you want to solve for the empirical formula. Take a 100 g sample which will give you
40.1 g oxygen, 39.8 g copper, and 20.1 g sulfur.
mols O atoms = 40.1/16 = 2.51
mols S atoms = 20.1/32.1 = 0.626
mols Cu atoms = 39.8/63.54 = 0.626
Now you want to find the ratio of the Cu to S to O atoms with the smallest whole number being 1.00. The easy way to do this is to divide the three numbers by the smallest value; i.e.,
mols O = 2.51/0.656 = 4.00
mols S = 0.626/0.626 = 1.00
mols Cu = 0.626/0.626 = 1.00
so the empirical formula, without the water, is CuSO4. Now, how much water is in the formula. CuSO4.xH2O
100% - 36.1% = 63.9% water. Again, taking 100 g sample we have
63.9 g CuSO4 and 36.1 g H2O.
mols CuSO4 = 63.9/159.6 = 0.400
mols H2O = 36.1/18.02 = 2
Again, dividing by the smallest number we get
mols CuSO4 = 0.400/0.400 = 1.00
mols H2O = 2/0.400 = 5.00 so x in the formula above is 5.00
and the empirical formula is CuSO4.5H2O
To determine the composition of the compound, we need to calculate the mass of each element in the compound. Let's assume we have 100 grams of the compound.
Given that the compound is 36.1% water, we can calculate the mass of water present as follows:
Mass of water = (36.1/100) * 100 grams = 36.1 grams
We now have 100 - 36.1 = 63.9 grams of the compound remaining after removing the water.
From the remaining compound, we see that it is 40.1% oxygen, 39.8% copper, and 20.1% sulfur. To calculate the mass of each element present, we can use the following equations:
Mass of oxygen = (40.1/100) * 63.9 grams = 25.6159 grams
Mass of copper = (39.8/100) * 63.9 grams = 25.3862 grams
Mass of sulfur = (20.1/100) * 63.9 grams = 12.8139 grams
So, after removing the water, we have approximately 25.6159 grams of oxygen, 25.3862 grams of copper, and 12.8139 grams of sulfur in the compound.