Rate Equations Flashcards
What are two ways in which Rate can be calculated using a graph?
- Gradient (y2-y1 / x2-x1)
- Gradient of the tangent of a curved graph
Rate of Reaction
Change in concentration / Time
Order of Reaction
How the concentration of the reaction affects the rate
Zero Order
Change in concentration has no effect on the rate
1st Order
Change in concentration is proportional to change in rate
e.g. doubling [A], rate doubles
2nd Order
Change in concentration has a squared proportional change on rate
e.g. if [A] doubles, rate quadruples
What is the only way order of reactions can be calculated?
Experiemnts
Rate constant- k
Only fixed at a particular temperature, changing the temperature will also change the value of k
e.g. An increase in temperature increases k as more particles have kinetic energy resulting in more frequent collisions (Ea ≥ Ea), increasing rate of reaction as there are more frequent collisions
Initial Rate
Take the gradient of the tangent at 0 minutes
Methods of measuring rates during experiments
- Change in pH
- Amount of Mass lost
- Volume of gas produced
Change in pH
pH meter used during regular intervals to calculate H+ ion concenctration
Amount of Mass lost
For reactions that produce a gas, place it on balance and measure
Mole calculations also used to calculate amount of reactants left
Volume of Gas produced
Measure gas produced using a gas syringe over a specific time
Ideal gas equations to find reactant concentrations
Colour change
Using a colourimeter- measures the absorbance of light in a coloured sample, the more concentrated, the darker, hence more light absorbed
Rate on a Straight Line graph
Zero order
