Chem Question!?

Question

I figured out the heat of Hydration for Copper Sulfate. From that, how do I decide if the chemical in powder form will generate steam at room temperature?

Answer 1

Copper II sulfate forms a penta hydrate, I think what you need to do is look up the heat capacity of CuSO4 and the heat capacity of water and determine if the heat released by the hydration is enough to raise the temperature of the total mass of material above 110 C (this is the temperature where CuSO4-5H2O loses 4 of the waters). It is unclear from the question how much water is being added; I would assume it is for the stoiciometric amount to make the pentahydrate. Note: because the CuSO4 is turning into CuSO4-5H2O during this water addition process, the heat capacity of the resultant mixture is probably changing, so the answer is only going to be approximate.

Say 20 C for room temp 1mole CuSO4 and 5 moles water.

Call X heat capacity for CuSO4; call Y heat capacity for water, and Z = heat of hydration

I think your equation will look like:

If: [1mol x X + 5mol x Y]kJ/mol C x [110-20 C] <

1 mole x Z kJ/mol (final units will be kJ) then steam forms

You have the value of "Z" you will need to look up the values for "X" and "Y". I am not absolutely certian this is correct, but it looks reasonable.