Chemistry DCP #4 Review

A man who was sleeping wakes up because he hears the smoke alarm go off in his house. Before opening the bedroom door, the man feels the door to see whether it is warm. He is assuming that heat would be transferred through the door by

• a. radiation

• b. conduction

• c. compression

• conduction d. convection

Which of these is the best example of heat transfer by radiation?

• a. Butter melts on warm bread.

• b. A satellite is warmed by sunlight.

• c. A ceiling fan cools a warm room.

• d. Puddles of water cool a warm tile floor

The potential energy contained in the bonds between the atoms of a compound is best defined as -

• a. kinetic energy

• b. nuclear energy

• c. mechanical energy

• d. chemical energy

A sample of aluminum with a mass of 50.00 grams changes from an initial temperature of 13.8oC to a final temperature of 2.4oC. The specific heat of aluminum is 0.897 J/g•oC. Calculate the change in thermal energy, and state whether heat was absorbed or released.

• a. Q = +510 joules; heat was absorbed

• b. Q = -510 joules; heat was released

• c. Q = +1660 joules; heat was absorbed

• d. Q = -1660 joules; heat was released

Two objects are suspended on strings 1 meter apart inside of a vacuum chamber. When the atmosphere is removed from the chamber, there is essentially no matter between the two objects, yet heat is still transferred between them. This transfer of heat must be happening primarily through the process of -

• a. radiation

• b. conduction

• c. convection

• d. refraction

A sample of copper has a mass of 250 grams. If this sample absorbs 5200 joules of heat, approximately how much will its temperature change? The specific heat of copper is 0.385 J/g•oC

• a. 54 C

• b. 21 C

• 7.7 C

• d. 8.0 C

A student learns that all of the particles within an object possess kinetic energy. Based on this fact, the student can conclude that all of the particles in the object -

• a. are in motion

• b. are covalently bonded

• c. are hotter than their surroundings

• d. contain the same atoms

Which of the following chemical reactions will produce a precipitate?

• a. ZnC₂ + Mg₂SO₄ >>>>>>> ZnSO₄ + MgCl₂

• b.3KBr + AlPO₄ >>>>> K₃PO₄ + AlBr₃

• c.Na₂CO₃ + CaCl₂ >>>>> CaCO₃ + 2NaCl

• d.NH₄OH + KCl >>>>>> KOH + NH₄Cl

A 0.2 g crystal of gypsum dissolves very slowly in 100 ml of water while the water is stirred. Which of these would cause the gypsum to dissolve faster?

• a.Stopping the stirring

• b.Lowering the air pressure

• c.Crushing the crystal

• d.Decreasing the water temperature

A solution which has a concentration that exceeds its predicted solubility at a certain temperature and pressure would be —

• a.dilute

• b.unsaturated

• c.supersaturated

• d.saturated