14. Rates Of Chemical Reactions Flashcards
What is the rate of reaction?
The speed at which a chemical reaction proceeds is known as the rate of reaction.
How is the rate of reaction measured?
It is the measure of the change in the concentration of the reactants or the change in the concentration of the products Ep unit time.
What are the factors which speed up a chemical reaction?
- increasing the concentration of the reactants
- increasing the temperature of the reactants
- increasing the surface area of the reactants
- mixing or stirring the reactants (agitation)
- adding a catalyst to the reactions
Why does increasing the temperature increase the rate of reaction?
It increases the speed of the particles of the reactants so they collide more frequently.
It gives the particles more energy so when molecules of reactant collide chemical bonds are more likely to break and the atoms in reactants can rearrange to make new products.
Why does increasing the concentration of reactants increase the rate of reaction?
The particles of reactants are more likely to collide and react when they are more concentrated.
Why does agitation of reactants increase the rate of reaction?
In keeps the particles of the reactants in contact with each other by removing the build up of products from around the reactants.
Why does dividing a solid reactant into smaller pieces increase the rate of reaction?
More of the surface area of the solid is exposed to the liquid reactant so more reactant particles are able to react at the same time.
What is an endothermic reaction?
Energy is absorbed to break the bonds within a molecule, therefore the surrounding environment loses temperature, gets colder.
What is an exothermic reaction?
Energy is released to break the bonds within a molecules, therefore the surrounding environment increases in temperature.
What are catalysts?
Chemical substances that speed up a reaction but they are not reactants, they do not take part in the reaction.
Why do catalysts speed up chemical reactions?
- they reduce the amount of activation energy that is required to convert the reactants into products
- they make it easier for the reactant particles to collide and thus react and form products.
