Reaction Rates

Question 1

what is the collision theory?

Answer 1

the greater the number of successful collisions (between particles) the faster the reaction rate.

Question 2

how does the temperature affect the rate of a reaction?

Answer 2

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

Question 3

in a graph of two reactions, how can you tell which reaction was faster?

Answer 3

the steepest sloping line is the faster reaction

Question 4

how does the concentration affect the rate of a reaction?

Answer 4

the higher the concentration, the more particles there are, so they will collide more often.

Question 5

why does the particle size affect the rate of a reaction?

Answer 5

when the particles are smaller, there is a larger total surface area, so they collide more often.

Question 6

how does the use of a catalyst affect the rate of a reaction?

Answer 6

a catalyst speeds up the reaction but is not used up in the reaction.

Question 7

what is an enzyme?

shape, optimum temperature

Answer 7

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.

Question 8

what are the three ways to determine the rate of a reaction?

Answer 8

• 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

Question 9

describe two experiments which would measure the rate of a reaction.

Answer 9

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.

Question 10

what is the equation for measuring the average rate of a reaction?

Answer 10

average rate = change in measurable quantity
————————————-
change in time

(measurable quantity is the concentration/mass/volume of reactants or products)

Question 11

what unit of measurement is used to measure:

• mass
• concentration
• volume?

Answer 11

mass- grams per second (gs-1)
concentration- moles per litre (mol l-1)
volume- cm cubed per second

Question 12

what are the four factors that affect the rate of a chemical reaction?

Answer 12

• temperature
• concentration
• particle size
• use of a catalyst