Water States
A student left a sealed jar of water outside. Initially, the water was a solid. After some time, it became a liquid. What happened to the water molecules?
Energy was transferred into the water, the molecules went from moving in place to moving around each other.
Scientists increased the speed of a substance's molecules. The molecules are moving around each other. What happened?
Energy was transferred into the substance, and it became a gas.
What happened to water molecules in a sealed tank when energy was removed?
The molecules would move slower.
A scientist tested two substances, only one changed phase after energy was removed. How?
The substance with a stronger attraction because the attraction pulled the molecules together because enough energy was removed.
What is kinetic energy?
Energy of an object that is in motion.
Lily’s substance has molecules that are moving around each other. If she adds energy and causes a phase change, what will happen?
The molecules will move faster, and the substance will be a gas (moving away from each other.)
A cook had sweet and sour foods. Only one changed phase after energy was added. Which one?
The food with the weaker molecular attraction changed first because enough kinetic energy was added to overcome attraction.
A scientist tested pink and green substances at room temperature. Only the pink changed phase. Why?
Pink has weaker attraction; moves away.
When are the aluminum molecules in Jamil's bicycle moving?
Always moving.
When energy is added to a substance, what usually happens?
Molecules speed up.
Divers found two substances at the sea bottom. Both are liquids at room temperature. Why did only one change phase after energy was removed?
The substance that changed first had a stronger molecular attraction. A sufficient amount of energy was taken out of the substance, allowing molecular attraction to pull the molecules closer together.
If we have two objects, a bike and a glass of water, which object has molecules that are moving?
Both have moving molecules.
The fuel tank's temperature dropped from 27°C to 3°C. What happened to the molecules?
They started moving slower.
How does kinetic energy change when molecules move faster?
Increasing.
If molecules lose kinetic energy, what is the likely outcome?
The molecules slow down and move closer together. If enough energy is transferred out to allow attraction to pull the molecules together, the molecules will change phase from either a gas to a liquid or a liquid to a solid
Anh measured the pond's temperature. It went from 18°C to higher. What happened to the water molecules?
The molecules' freedom of movement increased, causing them to move faster.
What happens when molecules' kinetic energy decreases?
The molecules slow down, if enough energy is taken out to allow molecular attraction to pull the molecules together, then a phase change will occur.
What change did a fuel scientist observe?
Liquid to gas.
Explain what happens to the molecules when a substance changes from gas to liquid.
They slow down, allowing molecular attraction to pull the molecules together, changing their freedom of movement from moving away from each other to around each other, this causes a phase change from gas to liquid.
Which statement is true about temperature and kinetic energy?
Higher temperature means higher kinetic energy.
A scientist observes a substance where molecules move away from each other, then around each other. What phase change occurred?
Condensation has occurred and the substance is now a liquid, but started as a gas.
Mario made chocolate, changing from liquid to solid. What happened to the molecules?
Energy was transferred out. Allowing the molecular attraction to pull the molecules together, which caused them to go from moving around each other, to moving in place.
How did a doctor slow down medicine molecules to cause a phase change?
Transfer energy out until molecular attraction can pull the molecules together, causing the medicine to become a solid.
Describe the process of adding energy to a solid to make it a liquid.
When energy is added to a solid, the amount of energy can be enough to overcome molecular attraction, changing the molecules' freedom of movement from moving in place to around each other, which is why we see a substance go from a solid to a liquid.
How can you determine the phase of a substance by it's molecules?