Flashcards in Kinetics and Equilibrium Deck (25):
how can the rate of reaction be calculated?
amount of reactant used or amount of product formed/time
what affect does a change in surface area of a solid have on the rate of reaction?
if there is more surface area that is in contact, it's more likely there will be successful collisions that lead to a reaction=faster rate of reaction
what affect does the concentration of solution have on the rate of reaction?
there's more particles so it's more likely that there will be successful and more frequent collisions that lead to a reaction=faster reaction
what affect does pressure have on the rate of reaction?
the particles are closer together causing more collisions that lead to a reaction=faster reaction
what affect does temperature have on the rate of reaction?
particles gain more energy and move faster if there is a higher temperature, so they collide more frequently
what affect does the use of a catalyst have on the rate of reaction?
a catalyst increases the rate of reaction without being used up. They do this by lowering the activation energy/ With a catalyst, more collisions result in a reaction, so the rate of reaction increases
what is activation energy?
the energy needed to get the reaction started
how does a catalyst speed up the rate of reaction?
it provides and alternate pathway with lower activation energy without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases
what is a catalyst?
a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
what symbol is used when reactions are reversible?
why are some reactions reversible?
some reactions can happen both ways: the reactants can make the products and the products can make the reactants
describe the reversible reaction of hydrated copper sulphate
- if you add water to it, it will become blue hydrated copper sulfate
- if you heat it up (remove the water), it will become white anhydrous copper sulfate powder
describe the effect of heat on ammonium chloride
- if heated, ammonium chloride splits up to form ammonia and hydrogen chloride
- if ammonia and hydrogen chloride reacts with each other, it forms ammonium chloride
what are dynamic reactions?
when forward and reverse reactions occur at the same time, and never stop
what is an equilibrium?
when the rate of the forward reaction is equal to the rate of the reverse reaction, the reaction is said to have reached equilibrium
how is an equilibrium reached?
if reversible reactions happen in a closed system (meaning none of the reactants or products can escape), equilibrium will always be reached
what is the effect of a catalyst on an equilibrium?
a catalyst doesn't alter the position of equilibrium, it only makes the reaction reach equilibrium faster
what happens if you remove a product from an equilibrium?
the equilibrium mixture changes to make more products, to try and balance out the reaction, just like it was previously. The same thing happens if you try and remove a reactant: equilibrium changes to produce more of the reactant
what are the effects of changing the pressure on the equilibrium position in reversible reactions?
- if the pressure increases, equilibrium moves to the side with the least molecules
- if pressure decreases, equilibrium moves to the side with the most molecules
what are the effects of changing temperature on the equilibrium position in reversible reactions?
- if the temperature increases, the endothermic reaction will increase, to absorb the extra heat
- if the temperature decreases, the exothermic reaction will decrease, to give out more heat
what happens to the amount of product in an equilibrium mixture when the temperature is changed?
- if the forward reaction is exothermic and the temperature is increased, the yield of products is decreased. If the temperature is decreased, the yield of products is increased
- if the forward reaction is endothermic and the temperature is increased, the yield of products is increased. If the temperature is decreased, the yield of products is decreased
describe an experiment to investigate the effects of changes in surface area of a solid on rate of reaction
1. put magnesium (of a known mass) in hydrochloric acid
2. time the reaction
3. change the form of magnesium to powder, strips or wires, whilst keeping the same mass
4. the more surface area (the smaller the pieces of magnesium) the faster the rate of reaction
describe an experiment to investigate the effects of concentration of solutions on the rate of reaction
1. put marble chips (of a known mass) into dilute hydrochloric acid
2. time the reaction
3. increase the concentration of hydrochloric acid (change the ratio of water to hydrochloric acid)
4. the more concentrated the hydrochloric acid (the lower the ratio of water) the faster the reaction
describe an experiment to investigate the effects of temperature on the rate of reaction
1. put magnesium powder (of a known mass) into a known mass of hydrochloric acid
2. time the reactions
3. repeat the experiment at different temperatures
4. the higher the temperature the faster the rate of reaction