Question

chemistry—unit 2 review
energy
think of energy as a quantity that is always involved when there is a change in the state of matter. when a substance gets hotter or colder or changes phase, energy is either transferred into or out of the system. one way energy is stored in a system is thermal energy (due to the motion of the particles). as particles move faster, their thermal energy increases. as the particles move faster, they tend to move farther apart from one another. temperature is a measure of the concentration of thermal energy in a system.
1a) true or false: energy is always transferred between two objects when they are in contact. explain your choice.
b) true or false: hot molecules take up more space than cold molecules. explain your choice.
because the pressure is closer together which means the particles are moving faster
c) true or false: heat and temperature are the same thing. explain your choice.
degree of hotness = temperature/depends on speed
quantity of hotness = heat/depends on speed&particles

Explanation:

1a) False. Energy is transferred between two objects in contact only when there is a temperature difference between them. If they are at the same temperature (in thermal equilibrium), no energy transfer occurs.
1b) True. As the text states, as particles (molecules) move faster (when they are hot), they tend to move farther apart from one another, thus taking up more space.
1c) False. Temperature is a measure of the average kinetic energy of the particles in a substance (a measure of the concentration of thermal energy), while heat is the transfer of thermal energy between two objects due to a temperature difference. They are related but not the same.

Answer:

1a) False
1b) True
1c) False