Calorimetry and Work Theory
In the context of the first law of thermodynamics what do the symbols q and W represent?
q= heat
W= work
When 100.0 g of water absorbs 4,184 J of heat, by how many degrees Celsius will its temperature increase?
10.0°C
Calculate the work (in L·atm) done when a gas expands from 1.0 L to 4.5 L against a constant external pressure of 2.0 atm.
-7.0 L·atm
If a reaction is performed in a bomb calorimeter, what thermodynamic variable is kept constant, and what does this imply about the work done by the system?
Volume is constant
A "Coffee-Cup" calorimeter is used to measure heat at constant pressure qp. What thermodynamic property is equal to qp in this scenario?
Enthalpy (delta H)
A piston compresses a gas from 5.0 L to 2.0 L using a constant pressure of 3.0 atm. How much work is done on the system in Joules?
+911.7 J
Define the difference between "Specific Heat Capacity" and "Heat Capacity"
Specific heat is the heat required to raise 1 gram of a substance by 1°C, while heat capacity is for an entire object or a given amount regardless of mass.
A 10.0 g piece of metal at 100.0°C is placed in 100.0 g of water at 25.0°C. The final temperature is 26.5°C. Calculate the specific heat of the metal.
0.85 J/g°C
A chemical reaction occurs at a constant pressure of 1.5 atm, causing the volume to increase from 1.0 L to 3.0 L. Calculate the work done in Joules.
-303.9 J
Explain the sign convention for work when a gas expands against an external pressure. Is W positive or negative for the system?
Negative. The system is doing work on the surroundings, resulting in an energy loss for the system.
A bomb calorimeter has a heat capacity of 5.00 kJ/°C. If the combustion of 1.00 g of a snack cracker causes the temperature to rise by 4.00°C, how many Calories (kcal) are in the cracker?
4.78 Calories
If a system does 500 J of work on its surroundings at a constant pressure of 1.0 atm, what was the change in volume in L?
+4.94 L
A hot metal block is dropped into a coffee-cup calorimeter containing cool water. If the specific heat of the metal is much lower than that of water, will the final equilibrium temperature be closer to the initial temperature of the metal or the water?
Closer to the water's initial temperature. Water’s high specific heat means it requires more energy to change its temperature compared to the metal.
50.0 mL of 1.0 M HCl and 50.0 mL of 1.0 M NaOH (both at 22.0°C) are mixed in a calorimeter. The temperature rises to 28.9°C. Calculate the H rxn of H2O formed.
-57.7 kJ/mol
A reaction takes place in a rigid, sealed steel tank. If the reaction produces 3.0 moles of gas and the pressure triples, how much work is done by the system?
0J