A mixture of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) and \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is heated until all the water is lost. If \(5.020 \mathrm{~g}\) of the mixture gives \(2.988 \mathrm{~g}\) of the anhydrous salts, what is the percent by mass of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) in the mixture?

Short Answer

Expert verified
The solution requires solving a system of equations. Please refer to the steps above for the details of the calculations needed. The final answer will be in the form of a percent which represents the percent by mass of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) in the mixture.

Step by step solution

01

Calculate the Mass of Water Lost

First, calculate the mass of water lost by heating the mixture. This is done by subtracting the final mass of anhydrous salts from the initial mass of the hydrated salts. In this case, \(5.020 \mathrm{~g} - 2.988 \mathrm{~g} = 2.032 \mathrm{~g}\) of water is lost.
02

Calculate the Amount of each Salt

The water lost comes from two sources: the 5 molecules of water in \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) and the 7 molecules of water in \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\). Therefore, the total mass of water lost can be written as the sum of the parts. Therefore, we can set up the following equation where x is the mass of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) and y is the mass of \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\): \(x\cdot \frac{5\cdot 2}{molar~mass~of~\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}} + y \cdot \frac{7\cdot 2}{molar~mass~of~\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}} = 2.032 \mathrm{~g}\)
03

Use the Fact that x + y equals the Total Mass of the Sample

Using the fact that \(x + y = 5.020 \mathrm{~g}\), we can solve the system of equations obtained in step 1 & 2 for x and y.
04

Calculate the Percent by mass of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) in the Mixture

Finally, once x and y are determined, the percent by mass can be calculated using the equation \(\%~by~mass = \frac{text{Mass of the part you are interested in}}{text{Total mass of the sample}} \cdot 100\%\). In this case, it would be \(\%~by~mass = \frac{x}{5.020 \mathrm{~g}} \cdot 100\%\)

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