a 2.50g sample of hydrate of calcium sulfate losses 0.523g of water when heated. what is the mass percent of water in the hydrate and the formula for the hydrate
difference of the two masses divided by the initial mass.
I believe Adam should reconsider his answer.
mass percent water = [amount water/mass sample]*100 = (0.523/2.50)*100 = ??
For the formula of the hydrate.
mols H2O = 0.523/18.01 = ??
mols CaSO4 = (2.50 - 0.523)/molar mass CaSO4 = ??
Find the ratio of mols water to 1 mol CaSO4, then express that as CaSO4.xH2O where x is the mols H2O per 1 mol CaSO4.
Post your work if you get stuck.
To calculate the mass percent of water in the hydrate, we can use the formula:
Mass percent water = (amount of water / mass of sample) * 100.
In this case, the amount of water lost is 0.523g and the mass of the sample is 2.50g. Plugging these values into the formula, we get:
Mass percent water = (0.523 / 2.50) * 100 = 20.92%.
Now let's find the formula for the hydrate.
First, we need to calculate the number of moles of water. We can do this by dividing the mass of water lost (0.523g) by its molar mass (18.01 g/mol):
Moles of H2O = 0.523g / 18.01 g/mol = 0.029 moles.
Next, we need to find the number of moles of CaSO4 (calcium sulfate). To do this, we subtract the mass of water lost (0.523g) from the initial mass of the sample (2.50g) to get the mass of CaSO4:
Mass of CaSO4 = 2.50g - 0.523g = 1.977g.
Now, we can calculate the moles of CaSO4 by dividing its mass by its molar mass (136.14 g/mol):
Moles of CaSO4 = 1.977g / 136.14 g/mol = 0.0145 moles.
To find the ratio of moles of water to moles of CaSO4, we divide the number of moles of water by the number of moles of CaSO4:
Ratio = Moles of H2O / Moles of CaSO4 = 0.029 moles / 0.0145 moles = 2.
Therefore, the formula for the hydrate is CaSO4 · 2H2O. This means that for every 1 mole of CaSO4, there are 2 moles of water molecules associated with it.