Reaction Rates Flashcards
what is the collision theory?
the greater the number of successful collisions (between particles) the faster the reaction rate.
how does the temperature affect the rate of a reaction?
the warmer the substances are, the faster the reaction will be, because heat gives the particles more energy so they move faster and collide more often
in a graph of two reactions, how can you tell which reaction was faster?
the steepest sloping line is the faster reaction
how does the concentration affect the rate of a reaction?
the higher the concentration, the more particles there are, so they will collide more often.
why does the particle size affect the rate of a reaction?
when the particles are smaller, there is a larger total surface area, so they collide more often.
how does the use of a catalyst affect the rate of a reaction?
a catalyst speeds up the reaction but is not used up in the reaction.
what is an enzyme?
shape, optimum temperature
an enzyme is a biological catalyst. their shape is specific to their substrate, so they each only work in one type of reaction. they work best at body temperature (35-40), and will become denatured at high temperatures.
what are the three ways to determine the rate of a reaction?
- measuring changes in the concentration of reactants or products
- measuring changes in the mass of reactants or products
- measuring changes in the volume of the reactants or products
describe two experiments which would measure the rate of a reaction.
1- reactants in flask, put on scales. as gas escapes, it will lose mass.
2-reactants in flask, gas syringe attached at top. syringe collects volume of gas.
what is the equation for measuring the average rate of a reaction?
average rate = change in measurable quantity
————————————-
change in time
(measurable quantity is the concentration/mass/volume of reactants or products)
what unit of measurement is used to measure:
- mass
- concentration
- volume?
mass- grams per second (gs-1)
concentration- moles per litre (mol l-1)
volume- cm cubed per second
what are the four factors that affect the rate of a chemical reaction?
- temperature
- concentration
- particle size
- use of a catalyst