Temperature & Tools
What tool did we use to measure water temperature, and what temperature unit did we record in our lab?
A thermometer; degrees Celsius (°C).
What is energy? Give one example of a change that energy can cause.
Energy is the ability to cause change or do work. Examples include moving an object or warming water.
What three states of matter did we compare in the States of Matter simulation?
Solid, liquid, and gas.
Name one hazard from the flask-and-balloon demonstration and one precaution that reduces that risk.
Examples: glass can break, so keep it secure on the tray and wear goggles; hot water can spill, so stay seated, keep the area clear, and follow the teacher's directions.
When warmer and cooler objects touch, in which direction does energy transfer overall?
From the warmer object to the cooler object.
What word describes an event or process in the world that we can observe and investigate, such as a rainbow or liquid rising in a thermometer?
A phenomenon.
At ordinary sea-level air pressure, at what Celsius temperatures does pure water freeze and boil?
Water freezes at 0°C and boils at 100°C.
What do we call the energy an object or particle has because it is moving?
Kinetic energy.
An ice cube holds its shape. Are its particles motionless? Describe how they move.
No. Particles in the solid vibrate around fixed positions.
In the food-coloring lab, which sample's color spread faster: hot water or cold water?
The food coloring spread faster in the hot water.
A room-temperature metal spoon becomes warmer in hot soup. Where did the energy come from, and which direction did it transfer?
It came from the hotter soup and transferred to the cooler spoon.
Which statement is an observation, and which is an explanation? A: 'The balloon became larger.' B: 'The air particles gained kinetic energy and moved faster.'
A is an observation. B is an explanation about what happened at the particle scale.
Complete this definition: Temperature is a measure of the __________ kinetic energy of the __________ in a substance.
Average; particles (atoms or molecules).
The same ball rolls slowly, then rolls quickly. When does it have more kinetic energy? Explain.
It has more kinetic energy when it rolls quickly. For the same object, greater speed means greater kinetic energy.
Describe one difference between the particles in liquid water and the particles in water vapor. Include spacing or how freely they move.
In liquid water, particles stay close together and move past one another. In water vapor, particles are much farther apart and move freely throughout the available space.
The color spread faster in hot water. Explain how that observation supports an idea about water-particle motion.
The pattern supports the idea that particles move faster on average in hotter water, helping the color mix and spread more quickly.
In the water-bottle activity, water warmed from 37°F to 80°F. Did the water gain or lose energy? What happened to its particles' average speed?
The water gained energy from its surroundings, including sunlight. Its particles moved faster on average.
All four bottles started at 37°F. At the water break: 16-oz clear = 80°F; 32-oz clear = 70°F; 16-oz gray opaque = 50°F; 16-oz gray transparent = 60°F. Which kept the water coolest, and how much did its water warm?
The 16-ounce gray opaque bottle kept the water coolest. Its water warmed by 13°F, from 37°F to 50°F.
The red liquid in a thermometer rises when it warms. Explain what changes about its particles and their spacing.
The particles move faster on average and become farther apart on average. The liquid expands and rises in the narrow tube. The individual particles do not get bigger.
Cup A has water at 10°C. Cup B has water at 50°C. Which cup's water particles have more kinetic energy on average, and how is their motion different?
Cup B. Its water particles have more average kinetic energy and move faster on average.
A cup of liquid water is sitting still on a table. What would a particle model show happening inside? How is this different from what we see with our eyes?
The water particles are constantly moving even though the cup and the water as a whole appear still. Individual particles are too small to see with our eyes.
The balloon on the flask grew when the flask was placed in hot water. Explain the change using energy, particle motion, and the space occupied by the air.
Energy transferred from the hot water into the flask and air. The air particles gained kinetic energy and moved faster on average. The trapped air expanded into the balloon and occupied more space.
Practice scenario: equal masses of water at 60°C and 4°C are mixed. No energy enters or leaves the water. Which final temperature is reasonable: 2°C, 32°C, or 64°C? Explain.
32°C. Energy transfers from the warmer water to the cooler water. With equal masses of the same substance and no energy exchange with the surroundings, the final temperature is halfway between the starting temperatures.
You want to keep a cold water bottle cool on a sunny hike. Suggest one change and explain how it would help.
Example: add a foam sleeve to slow energy transfer from warmer surroundings into the cold water. Keeping the bottle shaded can also reduce energy absorbed from sunlight.
A student presses the thermometer bulb against the bottom of a beaker and reads it immediately. Identify both problems and explain how to get a better measurement.
Keep the bulb in the water without touching the bottom or sides, so it measures the water. Wait about 30 seconds, or until the reading stabilizes. Read the scale at eye level and record °C.
Fix both statements: (1) Particles in cold liquid water are motionless. (2) Every particle in hot liquid water moves at exactly the same speed.
Cold liquid water particles still move. Particles in a sample move at a range of speeds. Hotter water has greater average particle speed and kinetic energy, not one identical speed for every particle.
Our mixing simulation uses different circle sizes to label particles that started in hot and cold water. Are real hot-water molecules a different size? What should we change in a drawing to show greater kinetic energy?
No. The different circle sizes are labels in the model. Draw water molecules the same size, and use longer arrows or more motion lines to show faster motion and greater kinetic energy.
The same balloon became smaller in ice water. A student says, 'The air particles shrank.' Correct the explanation using energy, motion, and spacing.
The air transferred energy to the colder surroundings. Its particles lost kinetic energy and moved more slowly on average. The balloon contracted, so the particles were closer together on average. The individual particles did not shrink.
After hot and cold water mix and reach a common temperature, do the particles stop moving? Explain what changes about the energy transfer overall.
The particles keep moving and colliding. Once the water is at a common temperature, there is no net transfer from a hotter region to a colder region within the mixture. Energy can still pass between individual particles.
Your group designs a device to keep a cookie warm using sunlight. What measurements would show whether it works, and how would you make a fair comparison to a cookie without the device?
Measure both cookies' starting temperatures and their temperatures after the same amount of time. Use similar cookies with the same starting temperature, place them in the same conditions, and compare one with the device to one without it. Repeat the test and use the data to improve the design.
FINAL CHALLENGE — Explain the Change
All teams: write your answer in 2 minutes. Worth 500 points.
Practice data: 150 g of water at 60°C is mixed with 150 g of water at 10°C in an insulated container. The final temperature is 35°C. Explain why BOTH starting samples changed temperature. Include the direction of energy transfer, what happened to particle motion, and why the final temperature is between the starting temperatures.
Energy transferred overall from the 60°C water to the 10°C water. Through interactions and collisions, particles in the warmer sample lost kinetic energy on average and slowed, while particles in the cooler sample gained kinetic energy on average and sped up. The mixture reached a common intermediate temperature of 35°C. The particles kept moving; coldness did not flow into the hot water.