Chemistry
Questions (including the gas laws, the heat capacity laws, and the laws of stoichiometry) with proofs
We can agree on that which we all observe and the laws of science (including the gas laws, the heat capacity laws, and the laws of stoichlometry).
1. (9 points) A 15.0 gram piece of metal is heated to 65.0 • C and then dropped into 175 grams of 24.0’C water. The system eventually comes to a stable temperature of 35.5 • C. (The specific heat of water is 4.184 J/g ‘ C) a. Energy is absorbed by the water. What is qw,u-ni?
b. Energy is released by the metal. What is qr….? (this one is easy)
C. What is the specific heat (Cs) of the metal?
3. (15 points) An empty balloon weighs 2.1 grams. At 25.0 .0 and 1.0 atm the balloon is filled with a pure substance. The filled balloon has a volume of 15.9 L and weighs 13.8 grams. Answer each question below with justification (prove your answer). a. What is the molar mass of the unlcnown substance? Would this balloon float in a room of 25.0 C ammonia INH3) gas.
b. If you heated that balloon to 100.•C, what would be the new volume?
2. (14 points) A student reacts 2.0 moles A and 4.0 moles of B in an insulated container. The reaction takes place M water (50.0 g), in a coffee cup. The water gains heat, raising its temperature 23.6.0 (AT). Water has a specific heat capacity of 9.189 J/g • C. A + 2 B —> 3C AHRxN = ?
a. Energy is absorb. by the water. What is Q.T.,
b. Energy is released by the reaction. What is cp., (this one is easy)
C. How much heat per mol of A (or per 2 mol of B), by the reaction (aim)?
d. ..other reaction, a student reacts 15 2 ttroll=01171 secm;d rnelaltIc’1:11:1; excess A. ‘hat
