# World of Chemistry

## Educators

Problem 1

Explain the difference between kinetic and potential energy.

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Problem 2

Why isn’t all energy available for work?

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Problem 3

Explain what is meant by the term state function. Provide examples of state functions.

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Problem 4

Which ball has the higher potential energy? Explain.

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Problem 5

The law of conservation of energy means that energy is a state function. Explain why.

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Problem 6

Explain the differences among heat, temperature, and thermal energy.

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Problem 7

Do each of the following depend on the amount of substance you have? Explain.
a. temperature
b. thermal energy

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Problem 8

Provide a molecular-level explanation of why the temperatures of a cold soft drink and hot coffee in the same room will eventually be the same.

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Problem 9

In which case is more heat involved: mixing 100.0-g samples of 90 °C water and 80 °C water or mixing 100.0-g samples of 60 °C water and 10 °C water? Assume no heat is lost to the environment.

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Problem 10

If 100.0 g of water at 90 °C is added to 50.0 g of water at 10 °C, estimate the final temperature of the water. Explain your reasoning.

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Problem 11

What is meant by potential energy in a chemical reaction? Where is it located?

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Problem 12

What does it mean for a chemical to have a low potential energy?

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Problem 13

In an endothermic reaction, do the reactants or the products have the lower potential energy?

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Problem 14

Are the following processes exothermic or endothermic?
a. When solid KBr is dissolved in water, the solution gets colder.
b. Natural gas $\left(\mathrm{CH}_{4}\right)$ is burned in a furnace.
c. When concentrated sulfuric acid is added to water, the solution gets very hot.
d. Water is boiled in a teakettle.

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