please help with chemistry struggling?

1.Which of the following is an endothermic reaction?

freezing water

condensation of steam

the reaction in a cold pack

combustion of methane

2. A copper block (20°C) is placed in contact with a lead block (30°C), which is already in contact with an iron block (70°C). Which of the following will happen?

Heat will flow from the copper to the lead to the iron until the temperatures are equal.

Heat will flow from the iron to the lead and from the lead to the copper until the temperatures are equal.

Heat will flow from the copper to the lead and from the iron to the lead until the temperatures are equal.

Heat will flow from the lead to the copper and to the iron until the temperatures are equal.

4. In the coffee-cup calorimeter you used in the laboratory, which of the following statements is true?

The water is the system and the ice is the variable.

The foam cups are not part of the system.

The water is part of the system.

The foam cups are the only part of the system.

5. Hydrogen gas explodes when burned with oxygen gas. Where does this energy come from?

kinetic energy of the hydrogen molecules

kinetic energy of the oxygen molecules

chemical bonds between hydrogen atoms and between oxygen atoms

work done on both oxygen and glucose molecules

6. What is the difference between an exothermic and an endothermic reaction?

Endothermic reactions release heat.

There are no changes in heat during either reaction.

Exothermic reactions absorb heat.

Endothermic reactions absorb heat.

7. Which of the following is an endothermic process?

rusting a nail in water

dissolving acetic acid in water

mixing strong hydrochloric acid and strong ammonium hydroxide

melting ice in water

8. Air flows according to differences in thermal energy. If a warm air mass is located in the northeast United States and a cold air mass is located in the southwest United States, from which direction will the winds blow?

northwest

southeast

southwest

northeast

9. Two liquids of different temperatures are separated by a barrier. The hot liquid is on the left side and the cold one is on the right side. Which of the following describes how the molecules move in heat flow?

Molecules from the left collide and transfer heat to the barrier, which transfers heat to the right side.

Molecules from the right collide and transfer heat to the barrier, which transfers heat to the left side.

Molecules from the left collide and transfer heat directly to the right side.

Molecules from the right collide and transfer heat directly to the right side.

10. A chemical reaction is carried out in a closed container. The energy absorbed by the chemical reaction is 100 kJ. How much thermal energy moves inward from the air or the walls of the container?

25 kJ

50 kJ

75 kJ

100 kJ

11. Which of the following is the abbreviation for a unit of energy?

K

°C

W

cal


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One Response to “please help with chemistry struggling?”

  1. Fly On The Wall says:

    1.Which of the following is an endothermic reaction
    the reaction in a cold pack
    because it absorbs heat. the others release heat.

    2. A copper block (20°C) is placed in contact with a lead block (30°C), which is already in contact with an iron block (70°C). Which of the following will happen?

    Heat flows in the direction of lower temperature until temperature is equilibrated.

    4. In the coffee-cup calorimeter you used in the laboratory, which of the following statements is true?

    The water is part of the system. (It’s the main part. The foam cups are part of the system too but they contribute a very small amount to the heat capacity of the system).

    5. Hydrogen gas explodes when burned with oxygen gas. Where does this energy come from?

    chemical bonds between hydrogen atoms and between oxygen atoms

    6. What is the difference between an exothermic and an endothermic reaction?

    Endothermic reactions absorb heat.

    7. Which of the following is an endothermic process?

    melting ice in water (takes heat to do that)

    8. Air flows according to differences in thermal energy. If a warm air mass is located in the northeast United States and a cold air mass is located in the southwest United States, from which direction will the winds blow?

    From hot to cold.

    9. Two liquids of different temperatures are separated by a barrier. The hot liquid is on the left side and the cold one is on the right side. Which of the following describes how the molecules move in heat flow?

    Molecules from the left collide and transfer heat to the barrier, which transfers heat to the right side.

    10. A chemical reaction is carried out in a closed container. The energy absorbed by the chemical reaction is 100 kJ. How much thermal energy moves inward from the air or the walls of the container?

    100 kJ

    11. Which of the following is the abbreviation for a unit of energy?

    cal (W is power, or energy divided by time)

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