Rate Of Reactions Flashcards
What is rate of reaction
Rate of reaction is defined as the change in concentration of reactants or products per unit at a specific temperature.
What is the formula of rate of reaction
Rate= increase in Concentration of reactants/ time taken for change
Or
Rate = decrease in concentration of reactants / time taken for change
What is measuring the rate of reaction
In practical situation it difficult to monitor and the change in concentration of reactants or products.
What can change in concentration be assessed by measuring changes in?
Volume of gases evolved or used
Mass of reactants or products
PH
Colour
What is the reaction between calcium carbonate and dilute hydrochloric acid.
CaCO^3(s) + 2HCL(aq) arrow CaCL2(aq) + H^2O(I) + CO^2(g)
Measuring the change of any below with time can monitor the rate of this reaction.
Mass of calcium carbonate
Volume of carbon dioxide
PH
What happen to the slope of the graph
Slope of the graph gives the rate at any point of the reaction. Note the rate of reaction is not constant throughout the reaction. The reaction start quickly: slow down as reactants are used up and then stop when one or both reactants are used up.
What happen when there is a stepper slope.
A stepper slope mean faster rate of reactions
What happen when there is a gently slope?
Gently slope mean a slower rate of reaction
Factors that affect rate
Concentration of reactants
Temperature of reactants
Light
Surface of reactants
Colour
Pressure of gaseous system
Concentration and rate
As concentration of reactants increases the rate of reaction. This is so because concentration mean there are more reactants in a given volume of reacting solution. There is therefore an increase frequency of particles collision taking place.
Temperature and rate
As temperature increase the rate reactants increase. This is because of a combination of several effects.
What some effects of temperature and rate
More particles achieve activation energy of the reaction.
Particles move at a greater speed make more frequency collisions.
Collisions are more energetic.
Also there is therefore a much greater chance of reaction.
Surface area of rate
The surface area of a substance is the amount of surface exposed. A number of smaller pieces have a large surface than large pieces of material.
Catalyst
A catalyst that increase the rate of a chemical reaction without itself undergoing any permeant chemical change
