<h3>Exothermic reactions
</h3>
These are reactions that transfer energy to the surroundings (ie the energy exits from the reaction, hence the name exothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter. A thermometer is used to detect the temperature increase.
Examples:
Combustion
Neutralisation between acids and alkali
<h3>Endothermic reactions
</h3>
These are reactions that take in energy from the surroundings (ie energy enters the reaction, which will help you to remember the name endothermic). The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become colder. A thermometer is used to detect the temperature decrease.
Example:
Electrolysis
The range in size of most atomic radii is approximately <span>5 × 10−21 m to 2 × 10−20 m. The rest of the choices do not answer the question above.</span>
The objects that are rubbed together will create charges among themselves due to friction.
(1) The balloon rubbed with a wool cloth will be charged.
(2) If she comb near a small, uncharged object nothing will change.
(3) This is a scientific investigation because it does not involved a step by step process to answer a scientific query.
Balanced chemical equation: C(s) + O₂(g) → CO₂(g).
Oxidation half reaction: C⁰ → C⁺⁴ + 4e⁻.
Reduction half reaction: O₂⁰ + 4e⁻ → 2O⁻².
Carbon is oxidized, it changes oxidation number from zero (in carbon element) to oxidation number +4 (in carbon dioxide).
Oxygen is reduced, it changes oxidation number from zero (in molecule of oxygen) to oxidation number -2 (in carbon dioxide).