States of Matter
Which state of matter has a definite shape and a definite volume?
A solid.
In a solid, do particles stay completely still?
No. They vibrate in place.
What does temperature measure?
The average kinetic energy of the particles in a substance.
What is the change from a solid to a liquid called?
Melting.
What is viscosity?
Viscosity is a substance's resistance to flowing.
Which state of matter has a definite volume but takes the shape of its container?
A liquid.
How do the particles in a liquid move differently from particles in a solid?
Liquid particles can slide past one another, while solid particles stay in fixed positions and vibrate.
If the particles in a substance begin moving faster, what happens to its temperature?
Its temperature increases.
What is the change from a gas to a liquid called?
Condensation.
Which liquid flows more slowly: a liquid with high viscosity or low viscosity?
A liquid with high viscosity.
A substance has no definite shape and no definite volume. It also expands to fill its container. What state of matter is it?
A gas.
What do the particles in a solid and a liquid have in common?
Their particles are always in contact with one another.
What is thermal energy?
The total kinetic and potential energy of all the particles in an object or substance.
What is the difference between evaporation and boiling?
Evaporation is vaporization that takes place only at the surface of a liquid. Boiling occurs when a liquid reaches its boiling point.
What is the main difference between a crystalline solid and an amorphous solid?
Crystalline solids have particles arranged in a pattern and melt at a particular temperature. Amorphous solids become softer when heated and do not melt at one particular temperature.
A student pours a liquid into a container with a different shape. The amount of liquid stays the same, but its shape changes. Explain how the movement and arrangement of the particles allow this to happen.
The particles in a liquid remain close together and in contact, but they can slide past one another. This allows the liquid to change shape while keeping a definite volume.
Imagine you have three particle diagrams:
Identify the three states of matter.
A: Solid
B: Gas
C: Liquid
A cup of water is heated on a stove. Explain what happens to the particles and what happens to the thermometer reading.
The particles gain thermal energy and move faster. Because their average kinetic energy increases, the temperature increases and the thermometer registers a higher temperature.
A cold glass of water is left on a table. After a while, drops of water appear on the outside of the glass. Where did the water come from, and what change of state occurred?
Water vapour, or gas, in the air lost thermal energy when it touched the cold glass and changed into liquid water. This change is called condensation.
A student pours honey and water at the same time. The water reaches the bottom of the container much faster. Which liquid has the higher viscosity, and what does this tell you about its ability to flow?
Honey has the higher viscosity. It resists flowing more than water, so it flows more slowly.
A sealed container is filled with a gas. The gas is transferred into a container that is twice as large. What will happen to the gas, and why?
The gas will expand to fill the larger container because gases do not have a definite volume. Their particles are spread out and are not in constant contact with one another.
Dry ice changes directly from a solid into a gas without becoming a liquid first. Explain what happens to the carbon dioxide particles during this process.
The dry ice absorbs thermal energy from the surrounding air. Its particles gain energy, move faster, and break away from their fixed positions in the solid, changing directly into a gas. This process is called sublimation.
Two objects have the same temperature, but one object contains many more particles than the other. Could they have different amounts of thermal energy? Explain why.
Yes. Temperature measures the average kinetic energy of the particles, while thermal energy is the total kinetic and potential energy of all the particles. An object with many more particles can therefore have more total thermal energy even if both objects have the same temperature.
Explain how a rain puddle eventually disappears from the ground as it changes from a liquid to a gas.
The puddle disappears because of evaporation. The Sun's radiation and warm air give energy to the water particles on the surface. These particles gain enough energy to change from a liquid to a gas, even though the water is not boiling.
A small paper clip is carefully placed on the surface of water. It can remain on the surface even though the paper clip is made of a material that is denser than water. Which property of water helps explain this, and what causes this property?
Surface tension helps explain this. Surface tension is an inward force, or pull, among the molecules in a liquid that brings the molecules on the surface closer together.