WAEC Chemistry questions: Rates of chemical reaction

16 questions with answers and explanations. Tap an option to check yourself.

1. Question 1· Rates of chemical reaction· WAEC

   Which of the following increases the rate of reaction between marble and dilute hydrochloric acid?

   • AUsing larger marble chips
   • BDiluting the acid
   • CCooling the acid
   • DUsing powdered marble

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   Explanation and discussion

2. Question 2· Rates of chemical reaction· WAEC

   Hydrogen peroxide decomposes faster when manganese(IV) oxide is added. The manganese(IV) oxide

   • Ais used up in the reaction
   • Bis a catalyst and is unchanged at the end
   • Cis a reactant
   • Dslows the reaction down

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3. Question 3· Rates of chemical reaction· WAEC

   Powdered marble reacts faster with dilute acid than marble chips of the same mass because the powder

   • Ais a different compound
   • Bhas a greater mass
   • Chas a larger surface area
   • Dis more concentrated

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   Explanation and discussion

4. Question 4· Rates of chemical reaction· WAEC

   The rate of a reaction can be followed by measuring

   • Athe size of the beaker
   • Bthe colour of the flask
   • Cthe volume of gas given off over time
   • Dthe room temperature

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   Explanation and discussion

5. Question 5· Rates of chemical reaction· WAEC

   For many reactions, a 10 °C rise in temperature roughly

   • Adoubles the rate
   • Bhalves the rate
   • Cleaves the rate unchanged
   • Dincreases the rate tenfold

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   Explanation and discussion

6. Question 6· Rates of chemical reaction· WAEC

   A catalyst speeds up a reaction by

   • Araising the temperature
   • Bproviding a pathway with lower activation energy
   • Cmaking ΔH larger
   • Dshifting the equilibrium to the right

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7. Question 7· Rates of chemical reaction· WAEC

   Which apparatus is suitable for following the rate of a reaction that gives off a gas?

   • Aa separating funnel
   • Ba burette alone
   • Ca thermometer only
   • Da gas syringe and a stop-clock

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8. Question 8· Rates of chemical reaction· WAEC

   Increasing temperature increases reaction rate mainly because

   • Amore particles have energy above the activation energy
   • Bparticles get bigger
   • Cthe catalyst works less
   • Dconcentration falls

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9. Question 9· Rates of chemical reaction· WAEC

   Which of these will increase the rate of reaction between calcium trioxocarbonate(IV) and dilute hydrochloric acid?

   • Ausing larger lumps
   • Busing powdered calcium trioxocarbonate(IV)
   • Ccooling the acid
   • Ddiluting the acid

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   Explanation and discussion

10. Question 10· Rates of chemical reaction· WAEC

    Manganese(IV) oxide speeds up the decomposition of hydrogen peroxide. It acts as

    • Aa reactant
    • Ba catalyst
    • Can inhibitor
    • Da product

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    Explanation and discussion

11. Question 11· Rates of chemical reaction· WAEC

    A catalyst speeds up a chemical reaction by

    • Araising the temperature
    • Bincreasing the concentration
    • Clowering the activation energy
    • Dchanging the products

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    Explanation and discussion

12. Question 12· Rates of chemical reaction· WAEC

    In the decomposition of hydrogen peroxide, manganese(IV) oxide

    • Aspeeds up the reaction and is unchanged at the end
    • Bis used up
    • Cslows the reaction down
    • Dis a reactant

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    Explanation and discussion

13. Question 13· Rates of chemical reaction· WAEC

    Powdered marble reacts faster with acid than lumps because

    • Ait is cooler
    • Bit is purer
    • Cit is heavier
    • Dit has a larger surface area

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    Explanation and discussion

14. Question 14· Rates of chemical reaction· WAEC

    The rate of a reaction that produces a gas can be followed by measuring the

    • Amass of the catalyst
    • Bcolour of the flask
    • Cvolume of gas collected at time intervals
    • Dboiling point of the mixture

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    Explanation and discussion

15. Question 15· Rates of chemical reaction· WAEC

    Increasing the temperature increases the rate of a reaction mainly because

    • Athe concentration falls
    • Bthe particles become bigger
    • Cthe activation energy increases
    • Dmore particles have enough energy to react

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    Explanation and discussion

16. Question 16· Rates of chemical reaction· WAEC

    Food preservatives work mainly by

    • Araising the temperature of food
    • Bspeeding up digestion
    • Cadding vitamins
    • Dslowing down the reactions that spoil food

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    Explanation and discussion