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DP IB Chemistry: SL

Topic Questions

Home / IB / Chemistry: SL / DP / Topic Questions / 1. Stoichiometric Relationships / 1.2 Reacting Masses & Volumes / Structured Questions: Paper 2


1.2 Reacting Masses & Volumes

Question 1a

Marks: 4
a)
In a firework, solid potassium nitrate, KNO3, decomposes to form solid potassium nitrite, KNO2, and oxygen, O2.

(i)

Write a balanced symbol equation for this reaction.

(ii)

Use section 6 of the data booklet to calculate the amount, in g, of potassium nitrate, KNO3, required to make 1.5 g of oxygen. Give your answer to 2 significant figures. 

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    Question 1b

    Marks: 1
    b)
    Use section 2 of the data booklet to calculate the volume of gas at STP, in dm3, that is produced in the reaction outlined in part (a). Give your answer to 2 significant figures. 

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      Question 1c

      Marks: 3
      c)

      Potassium can form a superoxide, KO2 (s), which will react with carbon dioxide, CO2 (g), to produce potassium carbonate, K2CO3 (s) and oxygen, O2 (g), as shown in the equation below.

      4KO2 (s) + 2CO2 (g) → 2K2CO3 (s) + 3O2 (g)

      (i)
      Calculate the amount, in moles, of 5.00 g of potassium superoxide. Give your answer to 3 significant figures

      (ii)

      Calculate the amount, in moles, and therefore volume, in dm3, of carbon dioxide which will react with the superoxide. Give your answer to 3 significant figures. 

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        Question 1d

        Marks: 1
        d)
        A student calculated that 4.86 g of potassium carbonate, KCO3, should be produced during the reaction outlined in part (c), 2.61 g of potassium carbonate, KCO3, was produced when the experiment was carried out. Calculate the percentage yield for the production of potassium carbonate. Give your answer to 2 decimal places. 

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          Question 2a

          Marks: 2

          A student carried out a series of titration experiments. Their results from their experiments are shown in the table below.

          Titration  Rough 1 2 3
          Final reading / cm3 25.45 21.95 43.65 22.10
          Initial reading / cm3 0.00 0.05 21.90 0.10
          Titre / cm3 25.45 21.90 21.75 22.00

          a)

          Calculate the mean titre using the concordant results. Give your answer to 2 decimal places.

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            Key Concepts
            Titrations

            Question 2b

            Marks: 2
            b)

            The student added 0.10 mol dm-3 hydrochloric acid, HCl (aq), to the burette and performed the titration using a 25.00 cm3 sample of an unknown carbonate solution. The equation for the neutralisation reaction is shown below. 

            M2CO(aq) + 2HCl (aq) → 2MCl (aq) + CO2 (g) + H2O (l) 

            (i)

            Using your answer to part (a), calculate the amount, in moles, of hydrochloric acid used. Give your answer to 2 decimal places. 

            (ii)

            Calculate the amount, in moles, of the aqueous carbonate solution. Give your answer to 2 decimal places. 

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              Key Concepts
              Titrations

              Question 2c

              Marks: 1
              c)
              Using your answer to part (b) (i) determine the concentration in mol dm-3 of the aqueous carbonate. Give your answer to 2 decimal places. 

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                Question 2d

                Marks: 4
                d)

                The student used 1.38 g of the unknown carbonate to make up a 250 cm3 standard solution for the titration outlined in part (a). Using section 6 of the data booklet, prove that the unknown carbonate is potassium carbonate, K2CO3

                Calculate the amount, in moles, of K2CO3 ………………………………………

                Calculate the concentration in, mol dm-3, of K2COsolution …………………………………

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                  Question 3a

                  Marks: 1
                  a)
                  3.75 g of zinc oxide, ZnO (s), was added to 150 cmof 1.00 mol dm-3 of sulfuric acid (aq) producing a salt. Write a balanced symbol equation for this reaction. 

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                    Question 3b

                    Marks: 3
                    b)
                    Using the equation in part (a) and section 6 of the data booklet, calculate the limiting reagent in the reaction. Give your answer to 2 significant figures. 

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                      Question 3c

                      Marks: 1
                      c)
                      Use your answer to part (b) and section 6 of the data booklet to calculate the amount, in grams, of the salt produced. Give your answer to 3 significant figures.

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                        Question 3d

                        Marks: 1
                        d)
                        Calculate the amount, in moles, of the excess reactant left over at the end of the reaction. Give your answer to 2 decimal places. 

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                          Question 4a

                          Marks: 2

                          A sample of pure magnesium nitrate, Mg(NO3)2, was decomposed by heating as shown in the equation below

                          2Mg(NO3)2 (s) → 2MgO (s) + 4NO2 (g) + O(g) 

                          A 0.75 g sample of Mg(NO3)2 was completely decomposed by heating.

                          a)

                          Calculate the amount, in moles, of magnesium nitrate that was decomposed. Give your answer to 2 decimal places.

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                            Key Concepts
                            The Mole

                            Question 4b

                            Marks: 2
                            b)

                            Calculate the total amount, in moles, of gas produced in the reaction. Give your answer to 2 decimal places. 

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                              Key Concepts
                              Ideal Gas Equation

                              Question 4c

                              Marks: 2
                              c)
                              Calculate the total volume, in m3, of gas produced at 333 K and 100 kPa. 
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                                Key Concepts
                                Ideal Gas Equation

                                Question 5a

                                Marks: 1
                                a)

                                90 cm3 ammonia gas, NH(g), is combusted in oxygen, O(g), to produce nitrogen oxide and water, H2O (l). What is the total volume of gases remaining when 90 cmof ammonia is combusted completely with 50 cm3 of oxygen according to the equation shown?

                                4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (l)

                                Deduce the limiting reagent for the combustion of ammonia, 90 cm3 ammonia gas, NH(g), is combusted in oxygen.

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                                  Key Concepts
                                  Avogadro's Law

                                  Question 5b

                                  Marks: 4
                                  b)
                                  Calculate the total volume, in cm3, of gases remaining for the reaction in part (a).
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                                    Question 5c

                                    Marks: 1
                                    c)

                                    Sketch a line on the graph below that shows the correct relationship between pressure and 1 over volume

                                    1-2-ib-sl-sq-easy-q5c

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                                      Question 5d

                                      Marks: 2
                                      d)

                                      At 25 oC and 100 kPa a gas occupies a volume of 35 dm3. Using the equation begin mathsize 14px style fraction numerator P subscript italic 1 V subscript italic 1 over denominator T subscript italic 1 end fraction italic equals fraction numerator P subscript italic 2 V subscript italic 2 over denominator T subscript italic 2 end fraction end style , calculate the new temperature, in oC, of the gas if the volume is decreased to 15 dm3 at constant pressure. 

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