Module 3 Chapter 10

A measure of how quickly a reaction occurs.

Rate of reaction = mass of product produced / time Rate of reaction = mass of reactant used / time Reaction rate = change in concentration / time

DRAW IT

That the initial rate of reaction is the highest. Reaction rate decreases the longer the reaction goes. When 1 of the reactants run out there will be no further reaction.

Concentration of reactants The temperature Surface area Pressure (for gases) Catalysts

The particles need to have sufficient energy (activation energy) The particles have to collide The particles should be in the correct orientation

Increasing the concentration of solution will increase the rate of reaction. As there are more reactant particles in a given volume, allowing for a higher frequency of collisions and therefore successful collisions.

Increasing the pressure for gases

Decreasing the concentration of solution will decrease the rate of reaction. As there are less reactant particles in a given volume, resulting in a lower frequency of collisions and therefore successful collisions.

If you increase the temperature of the reactants a higher proportion of the reactants have the activation energy or more this results in an increase in the frequency of successful collisions resulting in an increased rate of reaction. An increase in temperature also means that the reactants have a greater kinetic energy leading to an increase in the frequency of collisions and successful collisions resulting in a greater rate of reaction.

If you decrease the temperature of the reactants a lower proportion of the reactants have the activation energy or more this results in a decrease in the frequency of successful collisions resulting in a decreased rate of reaction. A decrease in temperature also means that the reactants have a lower kinetic energy leading to an decrease in the frequency of collisions and successful collisions resulting in a lower rate of reaction.

If you increase the surface area to volume ratio more reactant particles are available for collision, collisions are more likely, leading to a greater frequency of collisions and therefore an increase in rate of reaction.

If you decrease the surface area to volume ratio less reactant particles are available for collision, collisions are less likely, leading to a lower frequency of collisions and therefore an decreased in rate of reaction.

Catalyst increase the rate of chemical reactions, by lowering the activation energy providing another reaction pathway. So a greater proportion of the particles have the activation energy or more resulting in a greater rate of reaction.

New product formed Fizzing/ effervescence / gas given off Colour change

Measure the volume of gas produced in a given time using a gas syringe or upturned cylinder. Measure the change in mass over time. Measure how long it takes for a cross to disappear.

It is measured at t = 0

A tangent to the curve at that time is drawn and then using the tangent a gradient is calculated to work out rate of reaction.

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself.

They are not used up during a reaction

They may react with a reactant to form an intermediate ( a species formed during a reaction that reacts further and is not present in the final products) or may provide a surface on which the reaction can take place.

They are regenerated

Homogenous catalysts : is in the same physical state as the reactants it reacts with Heterogenous catalyst : is in a different physical state to the reactants it reacts with

Adsorption - weakly bonded onto the surface of catalyst Reaction Desorption - after reaction product molecules are released