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Exothermic and Endothermic Reactions
- Chemicals store energy in different amounts, so when chemical reactions occur, there is always a TRANSFER of energy when REACTANTS turn into PRODUCTS.
- This can be where reactants either ABSORB energy from the surroundings or RELEASE it.
- Energy can NOT be CREATED or DESTROYED, so the TOTAL amount of ENERGY in the UNIVERSE always stays the same BEFORE and AFTER a chemical reaction.
EXOTHERMIC REACTIONS:
- These are reactions that RELEASE ENERGY to the surroundings.
- They show a RISE IN TEMPERATURE.
- Common examples include COMBUSTION (like burning fuels), NEUTRALISATION reactions, and many OXIDATION REACTIONS such as metals reacting with acids.
Practical uses of Exothermic Reactions:
- HAND WARMERS: Utilise exothermic oxidation of iron.
- SELF-HEATING CANS: Depend on exothermic reactions for heating beverages.
ENDOTHERMIC REACTIONS:
- These reactions ABSORB ENERGY from the surroundings.
- They show a FALL IN TEMPERATURE.
- They are less common but can be found in processes like the reaction between CITRIC ACID and SODIUM HYDROGENCARBONATE, or THERMAL DECOMPOSITION.
Practical uses of Exothermic Reactions:
- SPORTS INJURY PACKS: The chemical reaction in these packs absorbs heat, causing them to cool without freezing.
Exothermic and Endothermic Reactions
- Chemicals store energy in different amounts, so when chemical reactions occur, there is always a TRANSFER of energy when REACTANTS turn into PRODUCTS.
- This can be where reactants either ABSORB energy from the surroundings or RELEASE it.
- Energy can NOT be CREATED or DESTROYED, so the TOTAL amount of ENERGY in the UNIVERSE always stays the same BEFORE and AFTER a chemical reaction.
EXOTHERMIC REACTIONS:
- These are reactions that RELEASE ENERGY to the surroundings.
- They show a RISE IN TEMPERATURE.
- Common examples include COMBUSTION (like burning fuels), NEUTRALISATION reactions, and many OXIDATION REACTIONS such as metals reacting with acids.
Practical uses of Exothermic Reactions:
- HAND WARMERS: Utilise exothermic oxidation of iron.
- SELF-HEATING CANS: Depend on exothermic reactions for heating beverages.
ENDOTHERMIC REACTIONS:
- These reactions ABSORB ENERGY from the surroundings.
- They show a FALL IN TEMPERATURE.
- They are less common but can be found in processes like the reaction between CITRIC ACID and SODIUM HYDROGENCARBONATE, or THERMAL DECOMPOSITION.
Practical uses of Exothermic Reactions:
- SPORTS INJURY PACKS: The chemical reaction in these packs absorbs heat, causing them to cool without freezing.
