5.00g of a mixture of magnesium sulfate crystals, MgSO4.7H2O, and copper sulfate crystals, CuSO4.5H2O, was heated until both salts has lost all water of crystallisation. There was a decrease in mass of 2.00g. Find the percentage of each hydrated salt in the mixture.
5.00g of a mixture of magnesium sulfate crystals, MgSO4.7H2O, and copper sulfate crystals, CuSO4.5H2O, was heated until both salts has lost all water of crystallisation. There was a decrease in mass of 2.00g. Find the percentage of each hydrated salt in the mixture.
Yes. Not an easy question, but it's more maths than chemistry.
If you let the mass of magnesium sulfate = m Then the mass of copper sulfate = (5 - m) Now work out the moles of each mol MgSO4.7H2O = m/246 mol CuSO4.5H2O = (5-m)/249.5
Now calculate the moles of water lost by each when heated mol water from MgSO4.7H2O = 7m/246 mol water from CuSO4.5H2O = 5(5-m)/249.5
Now calculate the mass of water lost by each mass water from MgSO4.7H2O = 18 x 7m/246 mass water from CuSO4.5H2O = 18 x 5(5-m)/249.5
and you know that the sum of the water masses = 2.00g
Therefore [18 x 7m/246] + [18 x 5(5-m)/249.5] = 2
Now solve for m
126m/246 + 450/249.5 - 90m/249.5 = 2
0.512m + 1.804 - 0.361m = 2
0.151m = 0.196
mass of magnesium sulfate heptahydrate = 1.3g mass of copper(II) sulfate pentahydrate = 3.7g
Yes. Not an easy question, but it's more maths than chemistry.
If you let the mass of magnesium sulfate = m Then the mass of copper sulfate = (5 - m) Now work out the moles of each mol MgSO4.7H2O = m/246 mol CuSO4.5H2O = (5-m)/249.5
Now calculate the moles of water lost by each when heated mol water from MgSO4.7H2O = 7m/246 mol water from CuSO4.5H2O = 5(5-m)/249.5
Now calculate the mass of water lost by each mass water from MgSO4.7H2O = 18 x 7m/246 mass water from CuSO4.5H2O = 18 x 5(5-m)/249.5
and you know that the sum of the water masses = 2.00g
Therefore [18 x 7m/246] + [18 x 5(5-m)/249.5] = 2
Now solve for m
126m/246 + 450/249.5 - 90m/249.5 = 2
0.512m + 1.804 - 0.361m = 2
0.151m = 0.196
mass of magnesium sulfate heptahydrate = 1.3g mass of copper(II) sulfate pentahydrate = 3.7g
It's amazing seeing how these questions are worked out!
Yes. Not an easy question, but it's more maths than chemistry.
If you let the mass of magnesium sulfate = m Then the mass of copper sulfate = (5 - m) Now work out the moles of each mol MgSO4.7H2O = m/246 mol CuSO4.5H2O = (5-m)/249.5
Now calculate the moles of water lost by each when heated mol water from MgSO4.7H2O = 7m/246 mol water from CuSO4.5H2O = 5(5-m)/249.5
Now calculate the mass of water lost by each mass water from MgSO4.7H2O = 18 x 7m/246 mass water from CuSO4.5H2O = 18 x 5(5-m)/249.5
and you know that the sum of the water masses = 2.00g
Therefore [18 x 7m/246] + [18 x 5(5-m)/249.5] = 2
Now solve for m
126m/246 + 450/249.5 - 90m/249.5 = 2
0.512m + 1.804 - 0.361m = 2
0.151m = 0.196
mass of magnesium sulfate heptahydrate = 1.3g mass of copper(II) sulfate pentahydrate = 3.7g