C-6 The rate and extent of chemical change

• How fast the reactants are changed in products

mean rate of reaction = quantity of reaction used//time taken Sanity ion product formed// time taken

• Must collide with enough energy -

• The more collisions there are the faster the rate of reaction • the energy transferred during a collision. Particles have to collide with enough energy for the collision to be successful • Activation energy- the amount of energy needed to break to bonds

• More collisions increase the rate of reactions

• When temperature increase the kinetic energy store increases and they move faster • As they are moving faster they will collide more frequently • The faster they move the more energy they gave so more collisions will have enough energy to make the reaction happen

• IF a solution is more concentrated it means there are more particles knocking about in the same volume of water • Similarly when pressure increases it means same number of particles occupy smaller space • makes collisions more frequent- therefore rate of reaction increases.

• IF reactants is solid then breaking it up will increase surface area to volume ratio • This means that for the same volume of solid particles will have more area to work on- so reactions will be more frequent

• Substance that speeds up a reaction without being used up itself within the reaction - not part of overall equation • • Different catalysts are needed for different reactions- but they all decrease activation energy- provide an alternate pathway- lower energy needed

• Different catalysts are needed for different reactions- but they all decrease activation energy- provide an alternate pathway- lower energy needed

• Biological catalysts - speed up rate of reaction in living things

• Colour change and precipitation • Change in mass- gas • Volume of gas given off

• Visual change • Observe a mark through solution and see how ;omg to tales to disappear- faster it takes faster rate • If reactants are coloured and products colourless you can see how long it takes to gain or loose colour • Subjective results • Cant plot

• measuring speed that produces a gas • As gas is related the mass leaving is measured in change in mass balance • IF take measurements at regular intervals a graph can be plotted • Most accurate- gas goes into room

• Gas given off • More gas given off means faster rate • nearest cm 3 • Graph • Can low plunger out

• Add set volume of HCL to conical flask • Add magnesium while on a mass balance • Record mass change at set intervals • Test with other concentrations • Plot on same graph and compare

• Both clear- go yellow • Add set amount of sodium • Place piece of paper in • Test time to no longer see black cross for different concentrations • No graph

• Overall change//overall time

• Draw a tangent and find relative gradient

• In some chemical reactions the products can react to produce original reactants

• A + B <=> C + D

• By changing the conditions e. g Ammonium chloride <====> Ammonium+ hydrogen to move left to right - heat to remove left to right- cool

• A reversible reaction is endothermic in one direction and exothermic in another. Same amount of energy transferred

• Hydrated copper sulfate <=====> Anhydrous copper sulfate+ water Left to right- endothermic Right to left- exothermic