States of Matter/Phase Changes
Heat always moves from....
What is hot to cold?
Is the ability of a substance to burn a physical property or a chemical property?
What is a chemical property?
Is freezing water a physical change or a chemical change?
What is a physical change?
What type of heat transfer occurs when you touch a hot pan and your hand gets warm?
What is conduction?
According to the Law of Conservation of Matter, matter can be created or destroyed during a physical change. True or false?
What is false?
This state of matter has particles that are very close together and vibrate in place.
What is a solid?
A student measures the boiling point of an unknown substance. Is boiling point a physical property or a chemical property?
What is a physical property?
Glass is shattered into several pieces. Is this a physical change or a chemical change?
What is a physical change?
What type of heat transfer causes warm water in a pot to rise while cooler water sinks?
What is convection?
A sealed container has 15.5 grams of water. The water freezes. What should the mass of the ice be?
What is 15.5 grams?
When a substance changes from a liquid to a gas, what phase change is occurring?
What is vaporization/evaporation?
A student adds salt to water and stirs it to see how it would dissolve. What physical property could the student determine from this investigation?
What is solubility?
A piece of metal rusts after being exposed to oxygen and water. What type of change occurred?
What is a chemical change?
You stand several feet away from a campfire and feel its warmth without touching it. What type of heat transfer is occurring?
What is radiation?
A student has 25 grams of a substance. After the substance changes from a solid to a liquid in a sealed container, what should the total mass be?
What is 25 grams?
A student places an ice cube on the counter. After 20 minutes, it becomes liquid water. What happened to the particles as the ice melted?
The particles gained thermal energy and moved more freely.
A student has an unknown substance. Which investigation would provide evidence of a chemical property:
measuring its boiling point
observing whether it catches fire
measuring its volume
observing its ability to be bent?
What is observing whether it catches fire?
A student stretches a piece of bubblegum. Another student burns a piece of paper. Which change is physical and which is chemical? Explain how you know.
Stretching the bubblegum is a physical change because its form changes but no new substance is produced. Burning the paper is a chemical change because new substances are produced.
A metal spoon sits in a pot of boiling water. After several minutes, the handle becomes hot. Explain how thermal energy traveled through the spoon.
Conduction. Thermal energy transferred through the metal by particle-to-particle contact
A balloon contains water. The water is heated and some changes into steam. The balloon remains sealed. Does the total mass increase, decrease, or stay the same? Explain.
The mass stays the same because matter is conserved. The water changed state from liquid to gas, but the matter was not created or destroyed.
A beaker of water is heated. The temperature of the water increases. What happens to the kinetic energy and motion of the water particles?
The particles gain kinetic energy and move faster.
A student performs two tests on an unknown substance. In Test 1, the substance boils at 58.8°C. In Test 2, the substance catches fire when exposed to a flame. Which test investigates a physical property and which investigates a chemical property?
Question: Three students make these observations:
Which investigations are most likely physical changes and which show evidence of a chemical change? Explain your reasoning.
A and B are physical changes. C is evidence of a chemical change because bubbles forming when two substances are mixed can indicate that a new substance was produced.
A student is standing near a campfire. They feel warmth from the fire, the air above the fire is rising, and a metal roasting stick becomes hot where it touches the fire. Identify the type of heat transfer involved in EACH situation.
A student places 40 grams of a substance into a sealed container. After heating, the substance changes from a solid to a gas. The student measures the mass again. The student says, “The mass must be smaller because gases don't weigh as much as solids.” Is the student correct? Explain using the Law of Conservation of Matter.
No. The mass should still be 40 grams. Changing from a solid to a gas changes the state and particle arrangement, but it does not create or destroy matter.