Chapter 3 Review

Question 1

What is a temperature-time curve?

Answer 1

This is a graph of the relationship between time and the temperature of a substance. Time = x-axis, temp. = y-axis

Question 2

What is the difference between boiling and evaporation?

Answer 2

Boiling - there is a chemical definition

Evaporating - the molecules “jumping” out of the water

Question 3

How do you show that particles are vibrating in a particle diagram?

Answer 3

parentheses

Question 4

In a temperature-time curve, how can you tell which form of energy is being absorbed or released?

Answer 4

Flat is Eph

Question 5

What is an exothermic reaction?

Answer 5

Where energy is released to the surroundings

Question 6

What is an endothermic reaction?

Answer 6

Where energy is absorbed from the surroundings

Question 7

What does phase energy go to do?

Answer 7

The energy is spent breaking bonds

Question 8

How do you assign values to Eph in an energy bar chart?

Answer 8

Solids = 1 bar, liquids = 2 bars, gasses = 4 bars

Question 9

How do you assign values to Eth in energy bar charts?

Answer 9

It needs to be consistent

Question 10

If a questions asks about energy being absorbed by ice of 2/3 of it is melted, what do you do the equation?

Answer 10

Multiply the answer by 2/3 to get the actual Q value

Question 11

What is the difference between Cal, kcal, and cal?

Answer 11

Cal and kcal are 1000 cal

Question 12

As a substance gets hotter or colder or changes phase, what happens to energy?

Answer 12

It is transferred either into or or out of the system

Question 13

What are the two key ways that energy is stored?

Answer 13

Thermal or phase energy

Question 14

How is energy stored thermally?

Answer 14

Through the motion of the particles

Question 15

How is energy stored through phases?

Answer 15

Through the attractions between particles

Question 16

What do attractions to the energy state?

Answer 16

They lower it

Question 17

To pull the particles apart, what must one do?

Answer 17

Add energy to the system

Question 18

What are the 3 ways that energy is transferred?

Answer 18

Heating (Q), working (W), and radiating (R)

Question 19

What is kinetic molecular theory?

Answer 19

All matter is composed of tiny particles in endless random motion. In solids, they vibrate and are locked in an orderly array. In liquids, they are still touching, but are free to move around each other. In a gas, they are moving very rapidly and are widely separated.

Question 20

When energy is transferred to a sample of matter, what two things can happen?

Answer 20

The particles speed up (temp. increases) or they get pulled apart (phase change. NEVER AT THE SAME TIME

Question 21

When energy is transferred to a sample of matter, what is unique about the 2 possibilities?

Answer 21

They are mutually exclusive –> they cannot happen at the same time

Question 22

how does the two possibilities shape the warming curve?

Answer 22

Since while the particles are being pulled apart there is no temperature increase, there is a flat line here.

Question 23

When the temperature of a solid, liquid, or gas is changing, what does energy have to do with this?

Answer 23

There is energy transfer via heating (Q)

Question 24

When a substance is undergoing phase change, which constant is used?

Answer 24

Hf for melting or freezing and Hv for evaporating or condensing

Question 25

When do you use the different quantitative energy equations?

Answer 25

Temp changing –> Q = mcΔT
Melt/freezeing –> Q = mHf
Evapor/condensing –> Q = mHv

Question 26

If more than one change is taking place, what must you do to solve the problem?

Answer 26

You must break the problem into steps (Qtotal = Q1 + Q2)