how can you tell that a chemical reaction has taken place?
a change in mass, heat being taken in or given out, bubbles are formed or there is a change in colour
define reactants
substances used to start a chemical reaction
define product
substances produced in a chemical reaction
define variable
any factor that can be controlled, changed or measured during an investigation
define collision theory
this means that for a reaction to occur reactants must collide
what are some of the most common variables in a reaction
temperature, surface area, concentration and catalysts
how does temperature affect a rate of reaction
it creates more heat energy in the substance and the particles will have more energy to move around so the particles have more opportunity to collide therefore increasing the rate of reactions
how does concentration affect a rate of reaction
a concentrated solution contains more solute than a diluted one so therefore there are particles with more collision opportunity to increase rate of reaction
what are the two ways to increase the concentration in an investigation
using a more concentrated solution - more solute in the same volume of solvent and using the same solute particles in a lower volume of solvent
define catalyst
a chemical that speeds up a reaction
define enzyme
a biochemical catalyst found in our bodies
how does a catalyst affect a rate of reaction
catalysts speed up a reaction without