Topic 6 Summary Cards

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increasing collisions. ne HOT O>> HO 9 Catalysts + Rate Catalyst = a substance that speeds up a reaction without. being used up. -Different catalysts are needed for different reactions, but they all work by decreasing the activation energy. done by providing an alternative reaction activation energy. pathway with a lower EXAMPLE: Enzymes (biological) Catalyse reactions in living things. Болаша without catalyst 4--1 with. cataly it. Reaction progress Products Activation energy without catalyst Activation energy with catalyst (3 Required Practical I Colour change / precipitation Method I = put a mark. under the = can record visual change if initial solution is transparent and the product is a precipitate that beaker with the clouds the solution. initial solution. Add the reactant and see how long it takes for the mark to dilapear - the faster it dissapears, the quicker the reaction. method 2= if reactants are coloured and the product are colorless for vice versa), time how long it takes for the sountion to lose or gain its colour. 1 Results are subjective and a rate of reaction graph can't be plotted. Required Practical 2 5 volume of gas given off = the more gas given off during a period of time, the reaction. faster the Method = place solution + react ants in. a beaker. Place a bung / punger in the top and insert the gas syringe. Start the timer, then stop after I minute. Take a reading on the syringe. •You could also take measurements at regular intervals and plot a rate of reaction graph using this method. --If the reaction is too vigorous, the plunger / bung Can be blown out of the beaker. Reversible Endo + Exothermic Reactions - If the reaction is endothermic one way, it will be exothermic the other way. · Energy transferred from the surroundings by the endothermic reaction is equal to the energy transferred into the surroundings by the exothermic reaction.. E.g. Thermal decomposition of hydrated copper sulfate endo₂ hydrated copper sulfate anhydrous copper sulfate + water дехода Reversible Reactions A+B= C + D The products can react to form the reactants. at the -As reactants react, their concentrations fall, so the forward reaction will slow down, as more products are made and their concentrations rise, the backward reaction will speed up. Equilibrium = the forward + backward reactions are going same rate. Can only be reached if reaction takes place in a closed system inothing can get out or in). Dynamic equilibrium = both reactions are happening but there is g reactants no overall effect - concentrations + products are balanced and won't 7 change. - Equilibrium right = products > reactants - Equilibrium left = products < reactants Depends on = temperature, pressure, concentration + the reaction itself Le Chatelier's Principle - If you change the conditions of a = reaction aut. equilibrium, the system will counteract the change. Temperature = decrease the temp, equilibrium moves Produce more heat (exo thermic). Means more products for exo and less for endo. Pressure = only affects equilibrium involving gares. Increase the pressure, equilibrium reduces it (moves where there's less gas molecules). Decrease pressure, equilibrium increases it (moves where there's more gas molecules). = Concentration change concentration of either reactants or products: system won't be at equilibrium - system responces itself back to equilibrium. Increase reactant Concentration = more Producks. Decrease product concentration - reduces reactants. to (8