Discussion:
Solving various thermodynamics questions
1 - The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 130J of heat. As it expands, it does 76kJ of work. What is the change in internal energy for the system?
2 - A piston has an external pressure of 8.00 atm. How much work has been done in joules if the cylinder goes from a volume of 0.140 liters to 0.450 liters.
3 - A volume of 105mL of H2O is initially at room temperature (22.0oC). A chilled steel rod at 2.00oC is placed in the water. If the final temperature of the system is 21.3oC, what is the mass of the steel bar?
Use the following values:
specific heat of water = 4.18 J/(goC)
specific heat of steel = 0.452 J/(goC)
4 - The specific heat of water is 4.18 J/(goC). Calculate the molar heat capacity of water.
5 - It takes 47.0J to raise the temperature of an 11.3g piece of unknown metal from 13.0oC to 24.1oC. What is the specific heat for the metal?
6 - The molar heat capacity of silver is 25.35 J/moloC . How much energy would it take to raise the temperature of 11.3g of silver by 19.0oC ?
7 - What is the specific heat of silver?
8 - If this expansion occurs against an external pressure of 1.0 atm, how much work (in J ) is done during the expansion?
9 - A gas is compressed from an initial volume of 5.40L to a final volume of 1.20L by an external pressure of 1.00 atm . During the compression the gas releases 128J of heat.
What is the change in internal energy of the gas?
10 - A mole of X reacts at a constant pressure of 43.0 atm via the reaction
X(g)+4Y(g)→2Z(g), ΔHo =-75.0 kJ
Before the reaction, the volume of the gaseous mixture was 5.00 L . After the reaction, the volume was 2.00 L . Calculate the value of the total energy change, ΔE , in kilojoules.
11 - The change in internal energy for the combustion of 1.0 mol of octane at a pressure of 1.0 atm is 5084.2kJ .If the change in enthalpy is 5074.4kJ how much work is done during the combustion?
12 - What mass of natural gas (CH4) must you burn to emit 267kJ of heat?
CH4(g)+2O2(g)→CO2(g)+2H2O(g) ΔHorxn =-802.3kJ
13 - Determine the mass of CO 2 produced by burning enough carbon (in the form of charcoal) to produce 530kJ of heat.
C(s)+O2(g)→CO2(g)ΔHorxn =-393.5kJ
14 - In the following experiment, a coffee-cup calorimeter containing 100 mL of H2O is used. The initial temperature of the calorimeter is 23.0oC If 5.70g of CaCl2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of solution ΔH soln of CaCl2 is -82.8 kJ/mol.