Chemistry T10: Rate of reactions

State 2 formulas to find the rate of reaction

- Amount of reactant used up/time

- Amount of product formed/time

State the relationship between the gradient of a reaction graph and the rate of reaction

- Steeper/greater the gradient, greater/faster the rate of reaction

Define the term effective collision

Collisions between reactant particles that form product particles

State the factors reactant particles must possess in order to have effective collisions

- Collide with one another

- Collide with energy equal to or greater than activation energy

- Collide in proper orientation

State the factors that affect the rate of reaction

- Temperature

- Surface area

- Concentration

- Pressure

- Presence of a catalyst

Describe how temperature affects the rate of reaction in terms of collision theory

Higher temperature, faster rate of reaction

- Higher temperatures, reactant particles have more KE

- Reactant particles move faster and collide more often

- Number of particles with energy equal to or greater than activation energy increases

- Higher frequency of effective collisions between reactant particles

Describe how particle size affects the rate of reaction in terms of collision theory

Smaller particle size, faster rate of reaction

- Smaller particle size of reactant particles, total surface area exposed for reaction increases

- More collisions between reactant particles

- Higher frequency of effective collisions between reactant particles

Explain why there is a high risk of an explosion in flour mils and coal mines

- Presence of high concentration of fine particles

- Large exposed surface area of fine particles in a confined space

- In presence of an oxidant and ignition spark, rapid combustion of fine particles results in a dust explosion

Describe how concentration affects the rate of reaction in terms of collision theory

Higher concentration, faster rate of reaction

- More reactant particles per unit volume

- Reactant particles are closer to one another

- More collisions between reactant particles

- Higher frequency of effective collisions between reactant particles

Describe how the presence of a catalyst affects the rate of reaction in terms of collision theory

Prescence of catalyst, faster rate of reaction

- Provides an alternative pathway of lower activation energy than the original reaction

- Number of particles with energy equal to or greater than activation energy increases

- Higher frequency of effective collisions between reactant particles

Define the term catalyst

A substance that increases the rate of reaction but itself remains unchanged chemically and in its mass at the end of the reaction

State the 4 characteristics of catalysts

- Only a small amount is needed to speed up the rate of reaction

- Increases the rate of reaction but not the yield

- Selective in action, only acts on/speeds up certain reactions

- Can be poisoned/inactivated by impurities, preventing the catalyst from working

Define the term enzyme

Biological catalysts that catalyze chemical reactions in plants and animals

State whether enzymes are specific in their actions

Enzymes are specific in their actions (Obviously, since they are biological catalysts and you know that catalysts are also selective in their actions from studying, so good job)

Describe the effects of temperature on enzymes

- Enzymes operate best at 35°C-40°C

- If temperatures are too high, enzymes denature

- If temperatures are too low, enzymes are rendered inactive

State the relationship between pH and enzymes

Enzymes have a specific pH range at which they work best

State and describe the 2 uses of enzymes

- Manufacture of alcoholic drinks like wine and beer. Enzymes produced by yeast catalyze the conversion of sugar and starch into ethanol

- Biological washing powders. Effective in removing stains by protein-based substances like food and blood

Name the catalyst used in the Haber process

Iron

Name the catalyst(s) used in catalytic converters

Platinum/Rhodium

Name the catalyst(s) used in cracking

Silicon dioxide/Aluminum oxide