Chemistry 1024A/B Chapter 4: Chem1024b_2013_chapter04-1.pdf

1. The amount of energy released by burning a fuel source, measured in energy per mass, is called the fuel value. If all the energy obtained from burning 1.23 pounds of ethane (fuel value is 11.36 kcal/g) is used to heat 121.0 kg of water at an initial temperature of 20.6C, what is the final temperature?

2. A 1445 kg car is traveling down the road at 93.0 km/h. while traveling at this rate of speed, what is the kinetic energy of this vehicle in kilojoules?

3. when 1576 j of heat energy is added to 38.7 g of hexane, C6H14, the temperature increases by 18.0 C . calculate the molar heat capacity of C6H14.

4. If a system has 2.50 x 10^2 kcal of work done to it, and releases 5.00 x 10^2 kj of heat into its surroundings, what is the change in internal energy of the system?

5. when a 3.00 -g sample of RbBr is dissolved in water in a calorimeter that has a total heat capacity of 0.9690 kj .K^-1, the temperature decreases by 0.410 K, calculate the molar heat of solution of RbBr

a) A system does work on the surroundings equal to 64 J and the change in energy is -213 J. Calculate the heat J

b) If 6.40 kJ of heat is needed to raise the temperature of a sample of metal from 14°C to 28°C, how many kilojoules of heat will be required to raise the temperature of the same sample of metal from 31°C to 54°C?

c) If 137 J of heat is applied to a 34 g sample of mercury, how many degrees will the temperature of the sample of mercury increase?

d) What quantity of heat is required to raise the temperature of 57.4 g of gold from 27°C to 66°C?

e) For the reaction below ΔH = -296 kJ per mole of SO₂ formed.

S(s) + O₂(g) → SO₂(g)

(1) Calculate the quantity of heat released when 1.45 g of sulfur is burned in oxygen.

(2) Calculate the quantity of heat released when 0.522 mol of sulfur is burned in air.

(3)What quantity of energy is required to break up exactly 4 mol of SO₂(g) into its constituent elements?

1.) In a reaction, gaseous reactants form a liquid product. The heat absorbed by the surroundings is 26.0 kcal, and the work done on the system is 15,650 J. Calculate the change of inner energy of the system DE in kJ.

2.) Calculate the heat q transferred, when 25 g of water is heated from 18 °C to 92 °C?

3. A 300-g aluminum engine part at an initial temperature of 13 °C absorbs heat of 175 kJ. What is the final temperature after the heat absorption of the aluminum part?

(specific heat capacity of aluminum c_Al = 0.900 J/ g × K).

4.) Consider the following balanced thermochemical reaction equation for the mineral magnesite:

MgCO₃(s) ® MgO + CO₂(g) ; DH = + 117.3 kJ

(a) Is this reaction endo- or exothermic?

(b) What is DH of the reverse reaction?

(c) What is DH if 150 g of MgCO₃ are decomposed?

(d) What is DH if 10 mol of CO₂ react with an excess of MgO?

5. Acetylene burns in air by the following equation:

2 C₂H₂(g) + 5 O₂ ® 4 CO₂(g) + 2 H₂O(g) ; DH_R°= - 2511.6 kJ

Given DH_f° of CO₂(g) = - 393.5 kJ/mol and DH_f° of H₂O(g) = - 241.8 kJ/mol, find DH_f° of C₂H₂(g).