Heat Transfer
Classify the following as either endothermic or exothermic and give the sign of qsys:
a. Water evaporating
b. A person shivering
c. Freezing water
d. Cooking an egg
a. endothermic
b. exothermic
c. exothermic
d. endothermic
When 175 mL of water at 25C is mixed with 55 mL of water at 96C, what is the final temperature
of the mixture?
Assume qsoln = –379 J
What is 95.6C?
Calculate ΔH for the process
Hg2Cl2(s)⟶2Hg(l)+Cl2(g)
from the following information:
Hg(l)+Cl2(g)⟶HgCl2(s) ΔH=−224kJ Hg(l)+HgCl2(s)⟶Hg2Cl2(s)ΔH=−41.2kJ
265 kJ
The change in internal energy of the
system, Usys:
A system absorbs 55 kJ of heat and does 45 kJ of work
What is 10 kJ?
You have 12.0 grams of calcium chloride to 115 grams of water, and the solution temperature
increases from 29.2 °C to 35.0 °C.
Find the heat gained or lost by the
reaction, qrxn, in J. Assume that the solution has a specific heat of 4.18 J/g·°C.
What is 25.78 kJ/mol?
4NH3(g)+5O2(g)⟶4NO(g)+6H2O(l) ΔH=−907kJ
2NO(g)+O2(g)⟶2NO2(g) ΔH=−113kJ
3NO2+H2O(l)⟶2HNO2(aq)+NO(g) ΔH=−139kJ
Determine the total energy change for the production of one mole of aqueous nitric acid by this process.
495 kJ/mol
Find q when 25.0 g of water is heated from 22.0C to 100.0C.
What is 8151 J?
Calculate the enthalpy change for the decomposition of the following reaction:
COH2 +O2 = H2O + CO2
C-H: H= 414 kJ/mol
O-H: H= 464 kJ/mol
C=O: H=799 kJ/mol
What is -899 kJ/mol ?
Calculate the standard enthalpy of formation of n-butane, given that the standard enthalpies of combustion of n-butane, C(graphite) and H2(g) are –2878.5 kJ mol–1, –393.5 kJ mol–1 and –285.8 kJ mol–1 respectively.
What is -124.5 kJ/mol?