3.05 g of hydrated copper sulphate produce 1.94 g of anhydrous copper sulphate. Assuming complete removal of water of crystallization. Determine the formula of the hydrated copper sulphate.
First we need to find the mass of water removed:
Mass of water = Mass of hydrated copper sulphate - Mass of anhydrous copper sulphate
Mass of water = 3.05 g - 1.94 g = 1.11 g
Now we need to find the moles of each component:
Moles of anhydrous copper sulphate (CuSO4) = mass / molar mass
Moles of CuSO4 = 1.94 g / (63.6 + 32.1 + 16*4) g/mol
Moles of CuSO4 = 1.94 g / 159.6 g/mol
Moles of CuSO4 ≈ 0.0122 mol
Moles of water (H2O) = mass / molar mass
Moles of H2O = 1.11 g / (1*2 + 16) g/mol
Moles of H2O = 1.11 g / 18 g/mol
Moles of H2O ≈ 0.0617 mol
To find the ratio of moles of water to anhydrous copper sulphate, we divide the moles of water by the moles of CuSO4:
Mole ratio = Moles of H2O / Moles of CuSO4
Mole ratio = 0.0617 / 0.0122
Mole ratio ≈ 5.05
Since the mole ratio is close to 5, we can assume that there are 5 moles of water for each mole of anhydrous copper sulphate. Therefore, the formula of hydrated copper sulphate is:
CuSO4 * 5H2O
To determine the formula of the hydrated copper sulphate, we can start by calculating the mass of water lost from the hydrated compound.
1. Calculate the mass of water lost:
Mass of anhydrous copper sulphate = 1.94 g
Initial mass of hydrated copper sulphate = 3.05 g
Water lost = Initial mass - Final mass
Water lost = 3.05 g - 1.94 g
Water lost = 1.11 g
2. Determine the number of moles of water lost:
To determine the number of moles, we need to use the molar mass of water, which is 18 g/mol.
Number of moles of water lost = Mass of water lost / Molar mass of water
Number of moles of water lost = 1.11 g / 18 g/mol
Number of moles of water lost ≈ 0.06167 mol
3. Calculate the number of moles of anhydrous copper sulphate:
To calculate the number of moles of anhydrous copper sulphate, we need to use its molar mass. Copper sulphate (CuSO4) has a molar mass of approximately 159.61 g/mol.
Number of moles of anhydrous copper sulphate = Mass of anhydrous copper sulphate / Molar mass of copper sulphate
Number of moles of anhydrous copper sulphate = 1.94 g / 159.61 g/mol
Number of moles of anhydrous copper sulphate ≈ 0.01216 mol
4. Determine the ratio of moles of water lost to moles of anhydrous copper sulphate:
The ratio of moles of water lost to moles of anhydrous copper sulphate will give us the number of water molecules associated with each copper sulphate molecule in the hydrated compound.
Ratio = Moles of water lost / Moles of anhydrous copper sulphate
Ratio ≈ 0.06167 mol / 0.01216 mol
Ratio ≈ 5.07
This means that for every one mole of anhydrous copper sulphate, there are approximately five moles of water molecules associated.
5. Write the formula of the hydrated copper sulphate:
Using the ratio obtained, we can now write the formula of the hydrated copper sulphate.
CuSO4 · 5H2O
Therefore, the formula of the hydrated copper sulphate is CuSO4 · 5H2O.
To determine the formula of the hydrated copper sulphate, we can start by calculating the number of moles of each compound.
1. Calculate moles of anhydrous copper sulphate:
- Given: Mass of anhydrous copper sulphate = 1.94 g
- To find the number of moles, we need to know the molar mass of anhydrous copper sulphate.
- The molar mass of copper (Cu) is 63.55 g/mol, and the molar mass of sulphate (SO4) is 96.06 g/mol.
- The formula of anhydrous copper sulphate is CuSO4.
- Thus, the molar mass of anhydrous copper sulphate (CuSO4) is 63.55 + 32.07 + (4 * 16.00) = 159.62 g/mol.
- Now, we can calculate the moles of anhydrous copper sulphate:
Moles = Mass / Molar mass = 1.94 g / 159.62 g/mol ≈ 0.01215 mol.
2. Calculate moles of water:
- Given: Mass of water = Mass of hydrated copper sulphate - Mass of anhydrous copper sulphate
- Mass of water = 3.05 g - 1.94 g = 1.11 g
- The molar mass of water (H2O) is 18.02 g/mol.
- Now, we can calculate the moles of water:
Moles = Mass / Molar mass = 1.11 g / 18.02 g/mol ≈ 0.0615 mol.
3. Determine the ratio of the moles of water to the moles of anhydrous copper sulphate:
- Divide the moles of water by the moles of anhydrous copper sulphate:
Ratio = Moles of water / Moles of anhydrous copper sulphate = 0.0615 mol / 0.01215 mol ≈ 5.
Now, we can determine the formula of the hydrated copper sulphate by using the ratio of moles obtained in the previous step.
4. Write the formula:
- The formula of the hydrated copper sulphate is CuSO4·5H2O.
Therefore, the formula of the hydrated copper sulphate is CuSO4·5H2O.