Chapter 6 Thermochemistry Part 2

Question 1

Problem: An 80.0g piece of iron at 21.1C was placed in 65.0g of hot water. The temperature of the iron was raised to 65.3C.
What is the temperature change of the water?
Specific Heat capacity of Fe=0.451 J g^-1 C^-1;specific heat capacity of H20 =4.184 J g^-1 C^-1.

Question 2

What does this symbol means “H”?

Answer 2

Enthalpy

Question 3

What is enthalpy?

Answer 3

Since constant pressure is so often the “norm” in chemical experiments.

Question 4

Like Delta U, Delta H is…

Answer 4

Directly proportional to the quantity of material present.

Question 5

Like with work and heat, the sign of deltaH has information on the change in enthalpy…

Answer 5

DeltaH= “+” for heat or endothermic process
DeltaH=“-“ for heat export or exothermic process

Question 6

Hess’ Law

Answer 6

If a process is the sum of two or more reactions, then DeltaH for the overall process is equal to the sum of the DeltaH values for each constituent reaction(step).

Question 7

Problem:
If HCl(g) + KOH(s)—>KCl(S) + H2O(I). ^H=-203.6KJ
And H2SO4 + 2 KOH(s) —>K2SO4(s) + 2H2O ^=-342.4KJ
What is ^H i kJ for 2KCl(s) + H2SO —> 2HCl (g) +