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What is the percent of CdSO4 by mass in a 1.0 molal aqueous solution?

1. What is the percent of CdSO4 by mass in a 1.0 molal aqueous solution?

2. Calculate the amount of heat that must be absorbed by 10.0 gram of ice at -20 C to convert it to gaseous water at 110 C. Given:

Specific heat ice = 2.1 Joule/gram
water = 4.184 Joule/gram
steam = 1.84 Joule/gram
change in heat fusion =6.01 K Joule/mol H2O
change in heat vapor= 40.7 K Joule/mol H2O

Solution Preview

1. Molality (in m) = Moles of Solute/Mass of Solvent(in kg)

We must assume that there is 1 L of aqueous solution. Thus,

Moles of CdSO4 in 1 L of 1 molal aqueous solution = 1.00 mol

Thus, the mass = (1.00 mol)(112.411+32.065+4(15.994) g/mol) = 208.476 ...

Solution Summary

To find the solution we note that Molality (in m) = Moles of Solute/Mass of Solvent (in kg). We must assume that there is 1 L of aqueous solution. If we assume the density of 1molal solution is 1.00 g/ml, we can find the mass in 1 L of solution. The second question can be answered in two parts. For the first part, we must calculate the heat absorbed to go from the temperature of -20 to 0 C. In the second part we must calculate the heat absorbed to go from the temperature of 0 to 110 C.

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