March 27, 2015

Homework Help: Chemistry

Posted by Lance on Tuesday, June 7, 2011 at 8:25am.

(a) A 102-g sample of water is placed in an insulated container and allowed to come to room temperature at 21C. To heat the water sample to 41C, how much heat must you add to it?

(b) Consider the hypothetical reaction, being run in an insulated container that contains 102 g of solution.
2 X(aq) + Y(l) → X2Y(aq)

If the temperature of the solution changes from 21C to 31C, how much heat does the chemical reaction produce? (You can assume that this solution is so dilute that it has the same heat capacity as pure water.)
How does this answer compare with that in part (a)? (Enter your answer using only a number or fraction.)
This is of the value of q in part (a).

(c) If you wanted the temperature of 102 g of this solution to increase from 21C to 51C, how much heat would you have to add to it? (Try to answer this question without using a formula.)

(d) If you had added 0.02 mol of X and 0.01 mol of Y to form the solution in part b, how many moles of X and Y would you need to bring about the temperature change described in part c.
X mol Y mol

(e) Judging on the basis of your answers so far, what is the enthalpy of the reaction 2 X(aq) + Y(l) → X2Y(aq)?

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