Table showing experimental results for exothermic and endothermic reactions.

Let’s go step by step to figure out whether each reaction is exothermic or endothermic.

First, remember:
- Exothermic = releases heat → temperature goes UP (ΔT > 0), ΔH < 0
- Endothermic = absorbs heat → temperature goes DOWN (ΔT < 0), ΔH > 0

We’ll use common knowledge about these reactions since no actual temp data is given — but we can predict based on what usually happens.

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Reaction 1: Vinegar + Baking Soda

This is the classic “volcano” reaction. It fizzes and gets COLDER. That means it’s absorbing heat from surroundings → endothermic

→ Change in Temp: negative
→ Exo/Endo: Endothermic

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Reaction 2: Ammonium chloride + Water

When you dissolve ammonium chloride in water, the solution gets cold. This is a known endothermic dissolution.

→ Change in Temp: negative
→ Exo/Endo: Endothermic

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Reaction 3: Potassium nitrate + Water

Dissolving potassium nitrate also cools the water — another endothermic process.

→ Change in Temp: negative
→ Exo/Endo: Endothermic

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Reaction 4: Hydrochloric acid + Sodium hydroxide

This is an acid-base neutralization. These always release heat — very exothermic!

→ Change in Temp: positive
→ Exo/Endo: Exothermic

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Reaction 5: Calcium chloride + Sodium carbonate

This forms a precipitate (calcium carbonate). Most precipitation reactions are slightly exothermic, but this one actually releases noticeable heat — especially because calcium chloride dissolving is exothermic too. Overall, it’s exothermic.

→ Change in Temp: positive
→ Exo/Endo: Exothermic

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Reaction 6: Citric acid + Baking soda

Similar to vinegar + baking soda — it fizzes and gets colder. Used in bath bombs for cooling effect → endothermic.

→ Change in Temp: negative
→ Exo/Endo: Endothermic

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Now let’s fill in the table logically:

| Reaction Number | Substances to be mixed | Description of substances | Initial Temp (°C) | Final Temp (°C) | Temperature change (positive/negative/no change) | Change in Temp (°C) | Is the reaction Exothermic or Endothermic? |
|------------------|--------------------------------------------|----------------------------------|-------------------|-----------------|--------------------------------------------------|---------------------|---------------------------------------------|
| 1 | Vinegar + Baking Soda | Liquid + Solid | (e.g., 20) | (e.g., 15) | Negative | -5 | Endothermic |
| 2 | Ammonium chloride + Water | Solid + Liquid | (e.g., 20) | (e.g., 14) | Negative | -6 | Endothermic |
| 3 | Potassium nitrate + Water | Solid + Liquid | (e.g., 20) | (e.g., 16) | Negative | -4 | Endothermic |
| 4 | HCl + NaOH | Liquid + Liquid | (e.g., 20) | (e.g., 28) | Positive | +8 | Exothermic |
| 5 | CaCl₂ + Na₂CO₃ | Liquid + Liquid | (e.g., 20) | (e.g., 25) | Positive | +5 | Exothermic |
| 6 | Citric acid + Baking Soda | Liquid + Solid | (e.g., 20) | (e.g., 17) | Negative | -3 | Endothermic |

*(Note: Since no real temps were given, I used example values to show direction of change. In real lab, you’d measure before and after.)*

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Final Answer:

1. Endothermic
2. Endothermic
3. Endothermic
4. Exothermic
5. Exothermic
6. Endothermic