chemistry-rate of reaction and energy changes

What happens to the rate of reaction when the temperature is increased

The rate of reaction increases with a higher temperature as particles gain more energy and collide frequently

How can the rate of a chemical reaction be found

By measuring the quantity of a reactant used or the quantity of produt formed over time

What is a catalyst and what affect does it have on the rate of reaction

A catalyst speeds up the reaction by providing a different pathway with a lower activation energy without being used up

What are units of quantity and the units of rate for:

Volume

Mass

Amount of substance

Volume: cm3 or dm3 (units of quantity) cm3/s or dm3/s (units of rate)

Mass: g (units of quantity) g/s (units of rate)

Amount of substance: mol (units of quantity) mol/s (units of rate)

What is an exothermic reaction and what are some examples and uses?

An exothermic reaction releases heat to the surroundings so the temp of the surroundings increases

Reactions: combustion, oxidation, and neutralisation

Uses: handwarmers, self heating cans

What’s an endothermic reaction and what are some examples and uses

An endothermic reaction takes in heat from the surroundings so the temp of the surroundings decrease

Reactions: thermal decompostions, reaction of citric acid and sodium hudrogencarbonate

Uses: ice packs, melting

Describe collision theory and how it works

Collision theory explains how various factors affect rate of reactions.

Increasing the concentration of reactants in solution or the pressure of reacting gases increases the frequency of collisions and so increases the rate of reaction.

When can chemical reactions occur

Chemical reactions can occur only when reacting particles collide with each other and with sufficent energy

What is activation energy

Activation energy is the mininimum amount of energy that particles must have to react

What is an enzyme

A catalyst in biological terms

List all five factors which can affect the rate of reaction

Temperature

Concentration

Surface area

Catalysts

Describe and explain the effect on the rate of the reaction

Increasing Temperature

Increases the kinetic energy of particles leading to more frequent collisions

Decreasing pressure of a gaseous reaction

Increases volume meaning particles are further apart, decreasing the frequency of collisions

Increasing concentration

Results in more reactant particles in agiven volume, increasing the frequency of collisions

Decreasing surface area

Fewer particles are exposed for collisions which decreases the frequency of effective collisions