Question

What is the temperature change of the sodium chloride pack?

ΔT = Tf - Ti

ΔT = 21°C - 4°C = 17°C

What is the energy change of the sodium chloride pack?

ΔE = 4 kJ/mol

Blank 1 (Starting Temperature):
21
Blank 2 (Change in Temperature):
4
Blank 3 (Ending Temperature):
17
Blank 4:
4
Question 2
Is this reaction endothermic or exothermic?

a
Endothermic
b
Exothermic
Question 3
Does this reaction make a hot or cold pack?

a
Hot pack
b
Cold pack

Answer 1

Let's go through your questions step by step.

### Temperature Change Calculation:
You correctly calculated the temperature change (ΔT) as follows:

ΔT = Tf - Ti
ΔT = 21°C - 4°C = 17°C

### Energy Change:
It appears you have identified an energy change (ΔE), but you should ensure that this is consistent with the temperature change being calculated.

### Filling in the Blanks:
- **Blank 1 (Starting Temperature)**: **4°C** (this should reflect the initial temperature)
- **Blank 2 (Change in Temperature)**: **17°C** (this is the change you calculated)
- **Blank 3 (Ending Temperature)**: **21°C** (the final temperature after the change)
- **Blank 4**: **4 kJ/mol** (this is the energy change, assuming it's the energy change associated with the reaction)

### Question 2 - Endothermic or Exothermic?
- The reaction is **endothermic** (a). An endothermic reaction absorbs heat, which is consistent with a temperature decrease in the surroundings (like in a cold pack).

### Question 3 - Hot or Cold Pack?
- This reaction makes a **cold pack** (b). Since it's endothermic, it absorbs heat from its surroundings, making it feel cold.

### Summary:
- **Blank 1**: 4°C
- **Blank 2**: 17°C
- **Blank 3**: 21°C
- **Blank 4**: 4 kJ/mol
- **Question 2 Answer**: a (Endothermic)
- **Question 3 Answer**: b (Cold pack)