4.3 - Rates Of Reaction

a substance that increases the rate of a reaction, but is chemically unchanged at the end of the reaction -> by providing an alternative pathway with lower activation energy

• add dilute HYDROCHLORIC ACID to the conical flask • DELIVERY TUBE to connect this flask to an inverted measuring cylinder • add CALCIUM CARBONATE CHIPS into the conical flask and close the bung • measure the VOLUME OF GAS produced in a fixed time • repeat with different sizes of calcium carbonate chips

• increase in the surface area of the solid reactant -> rate of reaction will increase • because there will be more of the solid reactant particles available for reaction -> allowing more frequent and successful collisions

• measure 50 cm3 of SODIUM THIOSULFATE SOLUTION into a flask • measure 5 cm3 of DILUTE HYDROCHLORIC ACID into a measuring cylinder • draw a CROSS on a piece of paper and put it underneath the flask • add the acid into the flask and immediately start the stopwatch • look down at the cross from above and stop the stopwatch when the cross can no longer be seen • repeat using different concentrations of sodium thiosulfate solution

• increase in the concentration of a solution -> the rate of reaction will increase • because there will be more reactant particles in a given volume -> allowing more frequent and successful collisions

• dilute HYDROCHLORIC ACID is HEATED to a set temperature using a water bath • add the dilute hydrochloric acid into a conical flask • add a STRIP of MAGNESIUM and start the stopwatch • stop the time when the magnesium fully DISSOLVES • repeat at different temperatures and compare results

With an increase in the temperature, the rate of reaction will increase This is because the particles will have more kinetic energy than the required activation energy, therefore more frequent and successful collisions will occur, increasing the rate of reaction

• add HYDROGEN PEROXIDE into a conical flask • use a DELIVERY TUBE to connect this flask to a measuring cylinder upside down in water trough • add the CATALYST MANGANESE(IV) OXIDE into the conical flask and close the bung • measure the VOLUME OF GAS produced in a fixed time using the measuring cylinder • repeat experiment without the catalyst of manganese(IV) oxide or by using other catalysts and compare results

• increasing concentration • increasing temperature • increase the surface area of a reactant • use of a catalyst

• increasing the concentration means that there are more particles in a given volume • causes more collisions per second • leadeing to more frequent and successful collisions per second • if you double the number of particles, you will double the number of collisions per second • the number of collisions is proportional to the number of particles present

• increasing the pressure means that there are the same number of particles in a smaller volume • this causes more collisions per second • leading to more frequent and successful collisions per second • therefore, the rate of reaction increases

• increasing the temperature means that the particles have more kinetic energy • causes more collisions per second • leading to more frequent and successful collisions per second • the rate of reaction increases • a small increase in temperature causes a large increase in rate

• increasing the surface area means that a greater surface area of particles will be exposed to the other reactant • higher KE • causes more collisions per second • leading to more frequent and successful collisions per second • the rate of reaction increases If you double the surface area, you will double the number of collisions per second

• add a fixed volume of hydrochloric acid into a conical flask • use a delivery tube to connect this flask to an inverted measuring cylinder • add marble chips into the conical flask and close the bung • measure the volume of gas produced in a fixed time using the measuring cylinder • repeat with different sizes of marble chips

products can react to produce original reactants - presented by two arrows