Chemistry Lab Report- Exo and Endothermic Reactions

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Aim: To examine a number of different chemical reactions and determine if they are exothermic or endothermic.

Apparatus:
• Test tubes {Around 10-12 in number}
• Test-tube rack
• Spatula
• Digital thermometer { ± 0.1° C}
• Digital balance {± 0.01 g}
• Measuring cylinder {± 0.5cm³}
• Different chemicals

Introduction/Theory:
Exothermic reactions are those reactions that release energy in the form of heat. Endothermic reactions need to absorb energy in the form of heat to proceed. Enthalpy is the heat content of a substance. Enthalpy change is positive for an endothermic reaction, as energy is absorbed {for example in the form of heat absorbed, the test-tube becomes cool to touch} and negative in the case of exothermic reactions {the test-tube becomes warm/hot to touch}.

[pic] [pic]

Endothermic Reaction Exothermic Reaction

Data Collection:

Table 1- Record of the amount taken and the temperature change of the reactants.

| |Two substances taken |Amount taken in cm³ [± 0.5] OR g [± |Temperature before |Temperature after |Endothermic/Exothermic | | | |0.01] |mixing in °C [± 0.1] |mixing in °C [± 0.1] | | | | |Substance I |Substance II | | | | |1. |Sodium Hydroxide [l] + Dilute hydrochloric|10.0 cm³ |10.0 cm³ |27.9 |29.3 |Exothermic | | |acid [aq] | | | | | | |2. |Sodium Hydrogen Carbonate [l] + Citric |10.0 cm³ |10.0 cm³ |28.5 |28.0 |Endothermic | | |Acid [l] | | | | | | |3. |Magnesium powder [s] + Copper Sulphate [l]|1.00g |10.0 cm³ |27.7 |51.4 |Exothermic | |4. |Zinc granules [s] + Nitric Acid [l] |1.00g |10.0 cm³ |27.8 |32.8 |Exothermic | |5. |Potassium Chloride crystals [s] + Water |1.00g |10.0 cm³ |28.6 |22.9 |Endothermic | | |[l] | | | | | | |6. |Anhydrous Copper Sulphate [s] + Water [l] |1.00g |10.0 cm³ |27.5 |35.0 |Exothermic | |7. |Sodium Carbonate [s] + Ethanoic Acid [l] |1.00g |10.0 cm³ |27.4 |30.4 |Exothermic | |8. |Ammonium Nitrate Crystals [s] + Water [l] |1.00g |10.0 cm³ |26.9 |25.3 |Endothermic | |9. |Sodium Chloride crystals [s] + Water [l] |1.00g |10.0 cm³ |26.2 |25.8 |Endothermic | |10. |Magnesium ribbon [s] + Dilute Sulphuric |1.00g |10.0 cm³ |26.4 |54.5 |Exothermic | | |Acid [l] | | | | | |

Table 2- Percentage change in the temperature of the substances [after mixing].

| |Reactants |Temperature before mixing in...
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