4 Rates of reactions

how do reactions occur?

for a reaction to take place the reactants must..

• collide

• have the correct orientation for bond breaking

• have sufficient energy for the reaction to occur - how reactants are turned into products

what is the activation energy?

the minimum energy required by reactants for a chemical reaction to occur

how do you measure reaction rates?

• volume of a gas evolved

• mass of solid formed

• intensity in colour of solution

• pH

• temperature

what does the CEO acronym stand for?

more successful collision = faster reaction rates

C - collisions must occur

E - enough energy to overcome activation energy

O - orientation

what are reaction rates?

• the more frequently reactants collide, the greater the chance of a successful collision → increased reaction rate

for a reaction to occur…

• there must be enough acitvationnenergy, they must collide and they must have a favourable orientation

what are the factors that affect reaction rate?

• temperature

• surface area

• concentration

• pressure

what is frequency?

the number of collisions

what is proportion?

the number of collision that result in a reaction

what are catalysts?

• often transition metals

• catalysts temporarily bind the reactants providing an alternate reaction pathway by lowering the activation energy.

• the outcome of the product produced is unchanged

what factors causes the proportion of collisions too be more successful?

• temperature and catalysts

How do catalysts increase the rate of reactions?

they decrease activation energy which results in a greater proportion of successful collisions

• more collisions have the energy to overcome the activation energy

what are they types of catalysts and their qualities?

homogenous: same state as reactants and products

heterogenous: different state to reactants and products

which type of catalyst is preferred?

• heterogenous catalysts are generally preferred as they are more easier to remove and can be used at higher temps

what is an open system?

• an open system allows matter and energy to be transferred between itself and its surroundings

what is a closed system?

a closed system allows for th transfer of energy, but not matter, between inself and its surroundings

how does temperature affect reaction rate?

the increase in temperature increases the kinetic energy of reaction particles which increases the frequencyy of collision and proportion of collisions with sufficient energy to overcome the activation energy

how does surface area affect reaction rate?

smaller particles have a larger surface area and result in more exposed particles which leads to greater frequency of collisions and successful collisions

how does concentration affect reaction rate?

higher concentration means more particles = resulting in more collisions.

therefore, a greater number of successful collisions and frequency

how does pressure affect reaction rate?

particles come closer together resulting in an increased frequency of collisions and number of successful collisions