Chemistry Exp. 1/ Investigation #1

1. Which is an example of kinetic energy?

An arrow in flight

A ball right before it is dropped

A warm bicycle chain

A gallon of gasoline

An arrow in flight is an example of kinetic energy because it possesses both mass and velocity. As the arrow moves through the air, it has the ability to do work and transfer energy due to its motion. The arrow's kinetic energy is directly related to its speed and mass, with faster and heavier arrows possessing more kinetic energy.

Explanation

An arrow in flight is an example of kinetic energy because it possesses both mass and velocity. As the arrow moves through the air, it has the ability to do work and transfer energy due to its motion. The arrow's kinetic energy is directly related to its speed and mass, with faster and heavier arrows possessing more kinetic energy.

2. You leave each of the following items outside on a hot, sunny day. Once the sun goes down, which item will cool off the fastest?

Aluminum baseball bat

Gold bracelet

Wood bench

Copper penny

Gold is a good conductor of heat, meaning it can absorb and transfer heat quickly. On a hot, sunny day, the gold bracelet will absorb a significant amount of heat from the sun. However, once the sun goes down, gold's high thermal conductivity will allow it to release the absorbed heat quickly, resulting in faster cooling compared to the other items.

Explanation

Gold is a good conductor of heat, meaning it can absorb and transfer heat quickly. On a hot, sunny day, the gold bracelet will absorb a significant amount of heat from the sun. However, once the sun goes down, gold's high thermal conductivity will allow it to release the absorbed heat quickly, resulting in faster cooling compared to the other items.

3. You have four water samples at different temperatures. In which sample are the molecules vibrating at the fastest speed?

Water at 37 oC

Water at 99 oC

Water at 99 oF

Water at 299 K

The molecules in a substance vibrate faster as the temperature increases. Since 99°C is the highest temperature among the given options, the water at 99°C would have the molecules vibrating at the fastest speed.

Explanation

The molecules in a substance vibrate faster as the temperature increases. Since 99°C is the highest temperature among the given options, the water at 99°C would have the molecules vibrating at the fastest speed.

4. Match the following

Energy caused by the motion of molecules in an object

Stored energy within a system

Energy of a moving object

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5. While burning coal and charcoal, you notice that coal releases more heat than charcoal. That means that the chemical potential energy is ________________ in charcoal than in coal.

Lower

Higher

The same

The given answer, "lower," is correct because the statement indicates that coal releases more heat than charcoal when burned. This suggests that coal has a higher chemical potential energy compared to charcoal. Therefore, the chemical potential energy is lower in charcoal than in coal.

Explanation

The given answer, "lower," is correct because the statement indicates that coal releases more heat than charcoal when burned. This suggests that coal has a higher chemical potential energy compared to charcoal. Therefore, the chemical potential energy is lower in charcoal than in coal.

6. In a chemistry experiment, the total energy contained in a system is 45 J. After the system undergoes a chemical reaction, the total energy in the system is 39 J. Which of the following statements is true?

The surroundings lost 6 J

The surroundings gained 6 J

The surroundings did not lose or gain energy

This is impossible as a system cannot lose energy

According to the law of conservation of energy, energy cannot be created or destroyed, only transferred or transformed. In this case, the total energy in the system decreased from 45 J to 39 J, indicating that 6 J of energy was transferred out of the system. Since the energy cannot simply disappear, it must have been transferred to the surroundings, resulting in the surroundings gaining 6 J of energy.

Explanation

According to the law of conservation of energy, energy cannot be created or destroyed, only transferred or transformed. In this case, the total energy in the system decreased from 45 J to 39 J, indicating that 6 J of energy was transferred out of the system. Since the energy cannot simply disappear, it must have been transferred to the surroundings, resulting in the surroundings gaining 6 J of energy.

7. According to the law of conservation of mass, mass is __________________. Select ALL that apply.

Conserved during chemical reactions

Always conserved over time

Conserved during physical transformations

Never conserved

According to the law of conservation of mass, mass is conserved during chemical reactions, always conserved over time, and conserved during physical transformations. This means that the total mass of a system remains constant, regardless of any changes in the form or state of the substances involved. Mass cannot be created or destroyed, only transformed or rearranged.

Explanation

According to the law of conservation of mass, mass is conserved during chemical reactions, always conserved over time, and conserved during physical transformations. This means that the total mass of a system remains constant, regardless of any changes in the form or state of the substances involved. Mass cannot be created or destroyed, only transformed or rearranged.

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8. The image shows energy flowing from coal to a coal-fired power plant, to a power tower, and finally to a radio. Order the types of energy as they are converted from one type to the other in each stage of the process.

1st energy

2nd energy

3rd energy

4th energy

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9. When you touch an ice cube, heat is transferred from_____ to_____

When you touch an ice cube, heat is transferred from your finger to the ice cube. This is because heat always flows from a higher temperature object (your finger) to a lower temperature object (the ice cube) until both objects reach thermal equilibrium. Additionally, heat is also transferred from your hand to the ice cube since your hand is in contact with your finger.

Explanation

When you touch an ice cube, heat is transferred from your finger to the ice cube. This is because heat always flows from a higher temperature object (your finger) to a lower temperature object (the ice cube) until both objects reach thermal equilibrium. Additionally, heat is also transferred from your hand to the ice cube since your hand is in contact with your finger.

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