States of Matter & Heat Study Guide
***Make sure to study the 3 notes packets as well***
Section 1: States of Matter
1. What are the four states of matter we learn about this year?
solid liquid gas Plasma
2. What determines what state of matter we say a substance is in?
How the particles move, and how far apart they are from one another.
State of Matter / Volume (definite or indefinite) / Shape (definite or indefinite) / How do the particles move?Solid / definite / definite / Vibrate in place
Liquid / definite / indefinite / Slip and slide around each other
Gas / indefinite / indefinite / Particles move freely and quickly
Plasma / indefinite / indefinite / Particles move freely and quickly. The electrons have been stripped away from the atoms.
4. How are the particles in plasma different than the particles in a gas? How are they the same?
Gases and plasmas are both very high energy states of matter. Neither have definite shapes or volume. But, the particles in plasmas have taken in so much energy they actually have been torn apart! Their electrons have been stripped away.
Section 2: Change of state – endothermic and exothermic changes
5. What does the term “change of state” mean?
The process of a substance moving or changing from one state of matter to another, like a substance going from its liquid state to its gas state, or from its solid state to its liquid state.
6. What causes a change in state?
Adding or taking away heat. Particles get energy from heat, so it is adding or taking away thermal energy.
7. List the 5 changes of state we learned about.
Melting
Freezing
Condensation
Vaporization
Sublimation
8. Place the three states of matter (liquids, solids and gases) in the diagram below, according to their level of energy (least to greatest). Write in the name of each of the three endothermic changes of state in the correct place on the diagram.(melting, vaporization, sublimation).
9. When energy is taken in by a substance and changes state, it is called an
endothermic change.
10. What is a substances melting point? What is a substance’s freezing point?
The melting point is the temperature at which matter melts, when the particles gain enough energy to break free from their fixed positions (solid to liquid- this is endothermic). The freezing point is the same temperature as the melting point but it’s where matter freezes the particles lose enough energy to move back into fixed positions (liquid to solid- this is exothermic).
11. How are melting point and freezing point the same?
They occur at the same temperature.
12. Is the melting point the same for all substances? Explain your answer.
No. Ice cream melts when it isn’t even very cold. Gold needs lots of heat energy in order to melt. So, ice cream has a lower melting point than gold does. versus
Different substances have different melting points. Water, for instance, melts at 0 degrees Celsius (or 32 degrees Farhenheit)
13. Vaporization is the change of state from a liquid to a gas. This can occur in two ways. What are the two ways?
evaporation and boiling
14. What is a substance’s boiling point?
the temperature a substance needs to be in order to turn from a liquid to a gas, through boiling
The boiling point for substances vary. The boiling point of water is 100 degrees Celsius.
15. Describe two ways that evaporation is different than boiling.
Boiling is vaporization that happens all throughout a liquid. A liquid has to reach its boiling point in order to boil.
Evaporation only happens on the surface of a liquid. The top layer of particles takes in enough energy to vaporize. This can happen at temperatures far below the boiling point.
16. Why is sublimation unusual?
Because most substances go from solid to liquid and THEN to gas. In sublimation, the particles of a solid take in energy and go straight to a gas, without becoming liquids first.
17. Explain how solid air fresheners are examples of sublimation.
18. When energy is lost by a substance and it changes state, it is called an exothermic change.
19. Match the following circumstances with the change of state they describe:
a. melting
b. boiling
c. evaporation
d. sublimation
e. freezing
f. condensation
___d__ Dry ice makes “smoke” for your Halloween party.
___b__ You put water on the stove to cook pasta and it bubbles, turning to vapor.
__a___ You leave a Hershey’s bar in the car during the summer, and when you come back it is all gooey.
__e___ A factory pours molten steel into a mold, and it hardens into a faucet, to be installed in our classroom.
__f___ It is warm in the evening, but gets very cold overnight. In the morning, the grass is wet, even though it hasn’t rained.
___c__ You leave 4 mL of tea in a mug on your nightstand, and when you go to put the mug in the dishwasher, you only see a brown ring at the bottom of the mug.
Section 3 – Temperature and Thermal Energy
20. What is “temperature”?
Temperature is one way we measure how much kinetic energy the particles WITHIN a substance has. It is the average measurement.
21. What do we mean by “the average kinetic energy of the particles of a substance?” What is kinetic energy? How do we find an average?
The average is found by adding together all of the kinetic energy of each of the particles, and then dividing by the number of particles. So, the average is a number that shows, in general, how much kinetic energy each particle has.
22. How does the temperature of an object increase?
By adding thermal energy which increases the speed of the particles.
23. What are the three scales (languages) we can use when we talk about temperature?
Celsius, Fahrenheit and Kelvin
24. The Celsius scale was developed based on the freezing point and boiling point of water.
Fill in the table.
Freezing pt. of water / Boiling pt. of water / Average human body temp.Celsius / 0 / 100 / 37
Fahrenheit / 32 / 212 / 98.6
25. The Kelvin scale was developed with the idea that “zero” should mean no kinetic motion. What do we call the special number that means that none of the particles in a substance are moving?
Absolute zero is what we call 0 Kelvin. It means that none of the particles, and no part of the particles (like the electrons) is moving.
26. Use this graph to answer questions 27 to 34.
27. At point A, what state of matter is the substance in?
solid (not ice! this is not water!) Water does not melt at 700C.
28. At point B what is happening to the matter?
the solid melts and starts to become a liquid
29. At point C, what begins to happen to the substance? What state or states of matter is the substance in, between points C and D?
it is a liquid, and the liquid is heating up --- that’s why the line on the graph starts rising again
30. Point D starts another change of state. What is it called?
at point D the substance is vaporizing – going from a liquid to a gas
31. What state or states of matter is the substance in, between points D and E?
part of it is a liquid and part a gas. At D it is a lot of liquid and little bit of gas, but, as more energy is taken in, more and more of it turns to a gas; but the temperature doesn’t rise until ALL of it has turned to gas
32. Right after point E on the graph, what state or states of matter is the substance in?
It is a gas, increasing in temperature.
33. What is the melting point of the substance? What is the boiling point? How did you know?
The melting point is about 70 Celsius and the boiling point is 140 Celsius. We know this because 70 is where the substance starts turning into a liquid and 140 is where it starts to turn to a gas.
34. Is there a change in temperature during a phase change (freezing, melting, etc)?
No, the temperature will remain the same until the change of state is complete.
Section 4- Heat and Heat Transfer
35. What is heat?
Heat is the transfer of thermal energy from a warmer object to a colder object. Thermal energy, in nature, goes from areas where there is more of it, to areas where there is less of it. The energy that is exchanged in this transfer is known as heat.
36. What is the difference between heat and temperature?
Temperature is a measure of the average kinetic energy of the particles of a substance. To raise the temperature of a substance thermal energy can be added which increases the speed of the particles.
Heat is the transfer of thermal energy from a warmer object to a colder one.
37. What is conduction? Give an example.
Conduction is the transfer of thermal energy from one substance to another through direct contact. When you touch a hot skillet and it burns you - that is conduction.
38. What is convection? Give an example.
Convection is the transfer of thermal energy by the movement of a liquid or a gas. It works through convection currents – the swirling of liquids or gas due to changes in density.
Example: when you boil a pot of water.
39. What is radiation? Give an example.
When thermal energy moves by electromagnetic waves, like the sun heating the earth, or a campfire warming you.
40. In general, thermal energy tends to move from areas with more thermal energy to areas with less thermal energy. Warmer object to colder object.
41. What is thermal expansion?
Is the increase in volume of a substance due to an increase in temperature.