18.2 concentration time graphs

methods for continuous monitoring of rate

• monitoring by gas collection

• monitoring by mass loss

monitoring rate with colorimeter

the wavelength of the light passing through a coloured solution is controlled using a filter. The amount of light is absorbed by a solution is measured

half life

time taken for half of a reactant to be used up

first oder reactions have constant half lives

calculating the rate constant from the rate

draw the tangent to the curve at a specific concentration

the gradient of the tangent is calculated giving the rate of reaction

k = rate/ concentration

for a first order reactant

calculating the rate constant from the half life

k = ln2/ half life