[Part 3]- C8- the rate and extent of chemical change 💥

• although industrial catalysts [such as gold or platinum] are typically very expensive, they are the most effective catalysts for particular reactions

• moreover, although some catalysts may be very expensive, they’re cheaper than paying the extra energy needed, without a catalyst. • This is because, a higher temperature and pressure would be needed to have the same rate of reaction [without using a catalyst]

• catalysts, help the environment- as operating at lower temperatures and pressures, conserves fossil fuels [a non-renewable resource]

• ; operating at high temperatures and pressures, usually involves the use of fossil fuels. • therefore, catalysts combat climate change= conserving fossil fuels, doesn’t release carbon dioxide into the atmosphere.

• catalysts remain chemically unchanged at the end of the reaction [not used up]- meaning, they be be reused again and again. • meaning a tiny amount of a catalyst can be used, multiple times- making it more cost effective, for industrial purposes.

• catalysts in chemical plants, can eventually become ‘poisoned’- meaning they don’t work anymore. • This is because, impurities in the reaction mixture combine with the catalyst, and stop it from working properly.

• a reversible reaction, is a reaction in which the products of the reaction, can react to produce the the original reactants. • ⇌ [this is the symbol, for a reversible reaction]

• we can change the direction of reversible reactions, by changing the conditions.

• in reversible reactions, the reaction to the right is known as the forward reaction

• in reversible reactions, the reaction to the left is known as the backwards reaction

• in reversible reactions, the reactants are still on the left side, and the products are still on the right side. • [ ; if the reaction is written in reverse, the same rule applies.]

• if a reversible reaction is exothermic in one direction, the reversible reaction is then endothermic in the opposite direction. • ; the same amount of energy, is also transferred [in each case]

• an example of a reversible reaction, is: • heating the compound: ammonium chloride • and, heating hydrated copper sulfate

• ammonium chloride ⇌ ammonia + hydrogen chloride

• when we heat the compound, it reacts to form ammonia and hydrogen chloride • ; if we take the product and cool them down, they can then react together to reform the compound: ammonium chloride.

• by heating it, we can make the reversible reaction go forwards [and form ammonia and hydrogen chloride] • ; by cooling the reversible reaction, we can make it go backwards [and reform ammonium chloride]

• hydrated copper sulfate ⇌ anhydrous copper sulfate + water

• if hydrated copper sulfate [which is blue] is heated, it reacts to form: anhydrous copper sulfate [which is white] ; it also produces water. • but if we add water to grab anhydrous copper sulfate, the reaction reverses to hydrated copper sulfate

• an exothermic reaction, is a reaction that transfers energy from the reacting molecules to the surroundings [usually by heating]. • so the temperature of the surroundings increases. • think exit= exothermic reaction- heat is given out

• endothermic reactions are a reaction that take in energy, from their surroundings. • in endothermic reactions, the temperatures of the surroundings decreases [gets colder] • think in= endothermic reaction- energy is taken in.

• [chemical] equilibrium, is a state in a reaction where the rate of the forward reaction, is equal to the rate of the reverse reaction.

• In dynamic equilibrium, the concentration of the reactants and products remain constant over time, even though the reaction is still ongoing.