Unit 2 - Rates of Reaction

Question 1

What 4 things does the rate of reaction depend on?

Answer 1

• Temperature
• Concentration (or pressure in gases)
• Catalysts
• Surface area of solids (or size of solid pieces)

Question 2

Graphs for rate of reaction: what is the quickest reaction shown by?

Answer 2

The steepest line

Question 3

How can the rate of reaction be observed?

Answer 3

Either by measuring how quickly the reactants are used up or how quickly the products are formed

Question 4

What is the formula for measuring the rate of reaction?

Answer 4

rate of reaction = Amount of reactant used or amount of product formed ÷ time

Question 5

What are the 3 different ways that the rate of reaction can be measured?

Answer 5

1. Percipitation (when the product of the reaction is a ppte which clouds the solution)
2. Change in mass (usually given off as a gas)
3. The volume of gas given off

Question 6

Explain how rate of reaction can be measured by percipitation

Answer 6

• Observe a mark through the solution and measure how long is takes for it to dissapear
• The quicker the mark dissapears, the quicker the reaction
• This only works for reactions where the initial solution is rather see-through

Question 7

What is the problem with measuring the rate of reaction by percipitation?

Answer 7

The result is very subjective, because different people might not agree over the exact point over the exact point where the mark ‘dissapeared’

Question 8

Explain how rate of reaction can be measured by change in mass?

Answer 8

1. Measuring the speed of a reaction that produces a gas can be carried out using a mass balance
2. As the gas is released the mass dissapearing is easily measures on the balance
3. The quicker the reading on the balance drops, the faster he reaction

Question 9

Which is the most accurate way of measuring rate of reaction and why?

Answer 9

Measuring the change in mass because the mass balance is very accurate

Question 10

Explain how the rate of reaction can be measure by the volume of gas given off?

Answer 10

1. This involved the use of a gas syringe to measure the volume of gas given off
2. The more gas given off during a given time interval, the faster the reaction
3. Gas syringes usually give volumes accurate to the nearest mm

Question 11

Which reaction would you use to measure affect of breaking a solid up into small bits?

Answer 11

The reaction of hydrochloric acid and marble chips

Question 12

Which reaction is used to measure the effects of increased concentration?

Answer 12

Magnesium metal with dilute HCL

Question 13

Which reaction is used to measure the effect of temperature?

Answer 13

Sodium thiosulfate an hcl

Question 14

What reaction is used to show the effect of different catalysts?

Answer 14

The decomposition of hydrogen peroxide