rate if reaction unfinished

What must happen for a reaction to occur?

Particles must collide

What is rate of reaction?

The change of concentration/amount of a reactant or product per unit time

What is the formula for rate of a reaction?

Amount of a reactant used/product made all over time

What is collision theory?

For a reaction to occur, the particles must collide in the right direction

They must also have a minimum amount of kinetic energy

What is activation energy?

The minimum amount of energy required for a reaction to occur

What does maxwell boltzmann distrubution show?

Shows the energy in gas particles

How to find the total number of particles in a boltzmann distrubution curve?

Area under curve

What does the peak represent in a maxwell boltzmann distribution curve?

The most likely energy of a particle in a sample

What does the middle of the downward slope of the maxwell-boltzmann distrubution curve represent?

The mean energy the particles have

What does just before the end of the boltzmann curve represent?

Activation energy

What does the area after the activation energy represent in a boltzmann curve?

Particles here have energy greater than the activation energy and can react

How does temperature affect rate of reaction?

Increase in temp = increase in kinetic energy

Particles move faster so higher frequency of collisions

A lager proportion of the molecules will have energy greater than the activation energy

More successful collisions per second so rate of reaction increases

How does concentration affect rate of reaction?

Increase in conc = more particles in a given volume

Increases particle density, particles collide more frequently

More successful collisions per second so rate increases

How does pressure affect rate of reaction?

Increase in pressure = decreases the volume occupied by the gas

Gas particles are closer together so increases the number of particles per unit volume = higher frequency of collisions between particles.

More successful collisions per second, rate of reaction increases

How does increase in temperature change the boltzmann curve?

Curve shifts to the right

Peak is lower- bc energy is distrubution is greater among the particles

Total area under curve is SAME (bc same no.molecues)

But area under the curve beyond the activation energy iNCREASES (Bc more particles have energy greater than the activation energy)

How does a decrease in temperature change change the botzmann distrubution curve?

Curve shifts left

Peak is higher

Area under curve is the SAME

Area under curve beyond activation energy DECREASES. (Bc most of the particles dont have enough energy to react)

What is a catalyst?

A substance that increass the rate of a reaction by providing an alternative pathway that has lower activation energy without getting used up itself

The catalyst is chemicallly unchanged at the end of the reaction

What are catalysts used for?

To speed up a reaction- provides an alternative pathway

To make product faster and can be used to lower the temp required for a reaction (saves time + money)

Lowering temp =less co2 produced

What are the environmental benefits of using catalysts?

Lower temperatures and pressures are required.

This reduces energy and CO2 produced

Less waste is produced as catalysts allow scientists to use reaction with better atom economies

What is a heterogenous catalyst?

A catalyst that is in a different state to the reactants

What will increasing the surface area of the heterogenous catalyst do?

Increase rate of reaction bc more particles can react with the catalyst at the same time

What is a homogenous catalyst?

A catalyst that is in the same state as the reactants

What is an example of a homogenous catalyst?

Sulphuric acid to make an ester

what are catalytic converters and what are they made of?

Are in cars to reduce levels of pollution.

Made from a rhodium, platinum and palladium alloy

What does a catalyst do to the botzmann distrubution curve?

The catalyst lowers the activation energy so more particles now have enough energy to react

The line that means activation energy shifts further left

How can rate be measured in experiments with disappearing cross experiment? +drawbacks

place a cross on paper and time how long it takes for cross to disappear (/precipitate to form)

Subjective - use same observer to reduce errors

How can rate be measured in experiments with amount of mass lost? +safety

For reactions that produce a gas - place reaction on balance and measure the mass loss as gas is lost

Use fume cupboard if gas is harmful/toxic

How can rate be measured in experiments with volume of gas produced?

If a gas is produced, measure the amount of gas produced using a gas syringe - measure this over a set amount of time

What does the gradient represent on a rate of reaction graph?

Rate of reaction