8 original questions from New Regents. The worksheet, answer key, and browser practice are free.
Exothermic and Endothermic Reactions 4 questions
Exothermic and Endothermic Reactions
New Regents original practice • Name: ____________________ Date: __________ Show your work for written answers.
The reacting substances are the system. A positive q for the system means heat enters it. A negative q means heat leaves it.
Question 1
Which statement describes an exothermic reaction?
- Heat leaves the reacting system.
- Heat always enters the reacting system.
- No heat is transferred.
- The reacting system gains exactly one proton.
Question 2
A reaction draws heat from a surrounding water bath. Explain the sign of q for the reaction system and the expected change in the bath temperature.
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Question 3
Which sign represents heat released by the system?
- Positive
- Negative
- Zero
- Either sign is equally appropriate.
Question 4
A reaction releases 240 J to an insulated water bath. Give q for the reaction and q for the bath.
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Reading Insulated Water Baths 4 questions
Reading Insulated Water Baths
Use the information below to answer the questions.
A model places a sealed reaction vial in a water bath. Assume heat flows only between the reacting system and the bath, and the vial stores negligible heat. Each bath has the same mass.
| Trial | Initial bath temperature (°C) | Final bath temperature (°C) |
|---|---|---|
| P | 22.0 | 26.0 |
| Q | 22.0 | 19.0 |
| R | 22.0 | 23.0 |
Question 5
Which reaction is endothermic based on the bath readings?
- P
- Q
- R
- All three
Question 6
Calculate ΔT for the bath in P, including the sign.
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Question 7
Which trial shows the greatest heat gain by its water bath?
- P
- Q
- R
- All three have equal heat gain.
Question 8
A student calls P endothermic because the bath got warmer. Explain how identifying the system resolves the mistake.
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