Chemistry Review

Find the specific heat of copper using the following information and assuming no heat is lost to the surroundings. A 100.0 gram copper crucible is heated to 83.50 °C from an initial temperature of 21.00 °C as it absorbs 2.40x103 J .

0.384J/g°C

A 16.0 g sample of iron was heated from 0 °C to 35.0 °C. It absorbed 246.4 J of energy as heat.

0.44 J/g °C

A cast iron skillet is used to fry bacon. For optimal frying, the pan must be heated to about 178 °C from a room temperature, of 22.0 °C. It is known that 1.58 x 105 Joules of heat energy are absorbed by the pan to reach the desired temperature and the specific heat of iron is 0.450 J/g °C.

2.25 kg

To make a 4 cup pot of green tea, one must heat the water to the boiling point at standard pressure. If the pot contains 680 grams of water, and the temperature at the tap is 20.0 °C, how much heat must be absorbed by the water? (Use 4.18 J/g °C for the specific heat of water.)

2.27x105J

Carbon tetrachloride was commonly used as an organic solvent until it was found to be carcinogenic. How much heat is required to raise the temperature of 10.35 g of CCl4 from 32.1 °C to 56.4 °C? The specific heat of CCl4 is 0.85651 J/g °C.

215J

What process takes place when the average energy of a gas's particles decreases?

Condensation

Photosynthesis, the reaction plants use to make sugar, is an endothermic reaction. Which statement below best describes the energy of the products and reactants in the photosynthesis reaction?

Energy is absorbed during the reaction, making the energy of the products greater than the energy of the reactants.

Which of the following describes the process of sublimation?

H2O(s) → H2O(g)

What is the term for the amount of energy absorbed or released in a chemical reaction?

Heat of reaction

Which of the following causes a change in state from liquid to gas?

High kinetic energy

When methane, CH4, and oxygen, O2, are mixed in a stove and ignited, a lovely blue flame results. The balanced equation is: CH4(g) + 2O2(g) 2H2O(g) + CO2(g) What can be said about the energy involved in this chemical reaction? I. The average kinetic energy of the products is greater than that of the reactants. II. The chemical energy stored in the reactants is greater than the chemical energy stored in the products. III. Chemical energy in the reactants is changed into heat energy and light energy.

I, II, and III

In a calorimeter experiment, the specific heat of a metal is to be found to 2 significant figures by placing a heated metal sample in a known quantity of water. The masses of the metal sample and water are known to 3 significant figures and the calorimeter is of very high quality. What precision is required of the temperature readings?

Temperature change must be known to 2 significant figures.

Which of the following must happen for condensation to occur?

The concentration of the vapor must be above zero.

In an experiment to measure the latent heat of fusion for ice, a double polystyrene foam cup was used as a calorimeter. In addition, a cover is often placed over the top of the cup. Why are polystyrene foam cups used instead of glass beakers for this purpose?

The polystyrene foam cups prevent heat gain or loss to the environment.

If the concentration of the vapor is increasing, then which of the following is the cause?

The rate of vaporization is greater than the rate of condensation.

An ice cube is heated until it is completely vaporized. Which property in the ice cube changes during this process?

The speed of the water molecules

∆EUniverse = ∆ESystem + ∆ESurroundings = 0 The expression above is a representation of the law of —

conservation of energy

The more kinetic energy there is in a sample of matter, the —

higher the temperature

If melting rate and freezing rate are not the same, then the system is

not in equilibrium

The average kinetic energy of the particles in a sample of matter is measured as the —

temperature

During an endothermic reaction, heat content in the surroundings decreases because —

the reaction absorbs heat energy

Use the information in the table to answer the question. O2(g)-0 H2(g)-0 H2O(g)- -241.8 H2O(L)- -285.8 Which is the correct heat of reaction (∆ Hrxn) for the decomposition of two moles of water according to the following endothermic reaction? 2H2O(g) 2H2(g) + O2(g)

∆H°f= +483.6 kJ