9.60 g of hydrated nickel (II) sulfate is heated to produce 5.26 g of anhydrous compound NiSO4.
Calculate the number of moles of anhydrous nickel (II) sulfate.
Calculate the number of moles of water lost.
What is the empirical formula of the hydrate?
Review the first problem. This one is almost the same.
Thanks a lot :)
To calculate the number of moles of anhydrous nickel (II) sulfate, we need to use its molar mass and the given mass.
1. Find the molar mass of NiSO4 (anhydrous nickel (II) sulfate).
- The molar mass of Nickel (Ni) = 58.69 g/mol
- The molar mass of Sulfur (S) = 32.07 g/mol
- The molar mass of Oxygen (O) = 16.00 g/mol
- The molar mass of anhydrous NiSO4 = (58.69) + (32.07) + 4 x (16.00) = 154.75 g/mol
2. Calculate the number of moles of anhydrous nickel (II) sulfate.
- Moles = Mass / Molar mass
- Moles = 5.26 g / 154.75 g/mol = 0.034 moles
To calculate the number of moles of water lost, we need to determine the amount of water that was present in the original hydrated nickel (II) sulfate and subtract the amount of water remaining in the anhydrous compound.
3. Find the molar mass of water (H2O).
- The molar mass of Hydrogen (H) = 1.01 g/mol
- The molar mass of Oxygen (O) = 16.00 g/mol
- The molar mass of water (H2O) = (2 x 1.01) + (16.00) = 18.02 g/mol
4. Calculate the molar mass of the water lost.
- The mass of water lost = Mass of hydrated compound - Mass of anhydrous compound
- The mass of water lost = 9.60 g - 5.26 g = 4.34 g
5. Calculate the moles of water lost.
- Moles of water lost = Mass of water lost / Molar mass of water
- Moles of water lost = 4.34 g / 18.02 g/mol = 0.241 moles
The empirical formula of the hydrate refers to the smallest whole-number ratio of the elements present in the compound.
6. Calculate the ratio of moles between anhydrous NiSO4 and water lost.
- Ratio = Moles of anhydrous NiSO4 : Moles of water lost
- Ratio = 0.034 moles : 0.241 moles
7. Simplify the ratio to the nearest whole number.
- The simplified ratio is approximately 1 : 7
8. Write the empirical formula of the hydrate using the simplified ratio.
- The empirical formula of the hydrate is NiSO4·7H2O.