5.6.1.1 Calculating rates of reactions Quiz: AQA Combined Science, Unit 13

The 20 questions

1. What expression is used to calculate the mean rate of a reaction?

   • Quantity over time
   • Quantity plus time
   • Time over quantity
   • Quantity times time

2. Which pair of units is acceptable for rate of reaction when quantity is measured by mass or volume?

   • s/g or cm3/s
   • g.s or cm3.s
   • g/s or cm3/s
   • g/s or s/cm3

3. In what units can the quantity of a reactant or product be measured?

   • Moles per second
   • Joules or watts
   • Degrees Celsius
   • Grams or cm3

4. On a graph of product quantity against time, what does the slope of a tangent measure?

   • Instantaneous rate
   • Total yield
   • Activation energy
   • Mean rate

5. On a quantity-time graph for a chemical reaction, what does a steeper slope indicate?

   • Slower rate
   • Lower temperature
   • Zero rate
   • Faster rate

6. At what point on a reaction time curve is the rate fastest?

   • At the start
   • In the middle
   • After it flattens
   • At the end

7. (Higher tier) Rate of reaction can also be expressed in units of:

   • mol/s
   • s/mol
   • mol/cm3
   • cm3/mol

8. A reactant mass falls from 20 g to 8 g at a mean rate of 0.6 g/s. How long did it take?

   • 0.05 s
   • 7.5 s
   • 33 s
   • 20 s

9. (Higher tier) A tangent to a product curve at 40 s rises 1.2 cm3 over 20 s. What is the rate at 40 s?

   • 0.6 cm3/s
   • 1.2 cm3/s
   • 24 cm3/s
   • 0.06 cm3/s

10. A reaction forms 150 g of product in 2.5 minutes. What is the mean rate in g/s?

    • 60 g/s
    • 0.017 g/s
    • 1.0 g/s
    • 2.5 g/s

11. (Higher tier) A reaction uses 0.4 mol of reactant in 20 s. What is the mean rate in mol/s?

    • 50 mol/s
    • 0.02 mol/s
    • 0.2 mol/s
    • 8 mol/s

12. A mean rate of 0.25 g/s is maintained for 60 s. What mass of product forms?

    • 240 g
    • 15 g
    • 0.0042 g
    • 3.75 g

13. Estimate the mean rate: 98 g of product in 49 s.

    • About 4.8 g/s
    • About 49 g/s
    • About 2 g/s
    • About 0.5 g/s

14. (Higher tier) A tangent on a graph passes through (10 s, 2 cm3) and (50 s, 10 cm3). Its gradient is:

    • 5 cm3/s
    • 8 cm3/s
    • 0.125 cm3/s
    • 0.2 cm3/s

15. (Higher tier) 4.8 g of magnesium (Mr 24) reacts over 80 s. What is the mean rate in mol/s?

    • 0.025 mol/s
    • 0.2 mol/s
    • 0.00025 mol/s
    • 0.0025 mol/s

16. What does a horizontal flat section on a quantity time graph indicate?

    • Reaction is fastest
    • Temperature is rising
    • Reaction has stopped
    • Catalyst is exhausted

17. What does a tangent drawn on a curved reaction time graph allow you to determine?

    • Total yield
    • Instantaneous rate
    • Mean rate
    • Activation energy

18. Which method is used to find the rate of reaction at a specific time?

    • Measuring total time
    • Weighing final products
    • Calculating mean rate
    • Drawing a tangent

19. A reaction produces 90 cm3 of gas in 75 s. What is the mean rate?

    • 1.5 cm3/s
    • 1.2 cm3/s
    • 12 cm3/s
    • 0.83 cm3/s

20. A reaction loses 4.8 g of mass in 160 s. What is the mean rate?

    • 0.3 g/s
    • 0.003 g/s
    • 0.03 g/s
    • 0.77 g/s

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