Unit B

Energy and Matter in Chemical Change


  Conclusion

By organizing and classifying matter, the study of chemical substances and their changes is starting to make sense.



B13.10 Writing a chemical reaction
In this unit, you started out learning about the underlying structure of matter. You looked at the historical development of atomic theory, including the work of Dalton, Thomson, Rutherford, and Bohr, focusing on the experiments they performed that allowed them to develop their atomic theories. You learned about the subatomic particles of atoms and how this information is organized on the periodic table.

Once you finished learning about atoms, you learned about how atoms combine to form compounds. You learned how to identify ionic and molecular compounds and how to write chemical formulas and names for those compounds.

The next topic you studied was chemical reactions. You learned how to classify, balance, and predict products for the five main types of chemical reactions: formation, decomposition, single replacement, double replacement, and hydrocarbon combustion.

Finally, you studied chemical amounts by looking at the concept of the mole.

  Review Questions

Complete the following practice questions to check your understanding of the concepts you have learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. A substance in a chemistry lab was labeled with the following WHMIS symbol:




    What does the symbol mean, and what safety precautions should be taken?

    It means the substance can cause health hazards such as cancer, respiratory problems, or reproductive problems. The safety precautions should be to use only in a well-ventilated area and to use personal protective equipment.

  2. Which scientist determined that the atom was mostly empty space? What evidence did he collect to support this idea?

    Rutherford determined the atom was mostly empty space. He shot alpha particles at gold foil; most of the alpha particles passed straight through without being deflected at all.
  3. Identify the number of protons, electrons, and neutrons in an atom of selenium-74

    protons = 34
    electrons = 34
    neutrons = 40
  4. Draw a modified Bohr diagram for sulfide.

  5. How many electrons would an ion of cesium contain?

    An atom of cesium would contain 55 electrons. An ion of cesium has a charge of 1+, so it must have lost one electron; therefore, an ion of cesium will have 54 electrons.
  6. What happens to electrons in an ionic bond?

    Electrons are transferred. The metal atom will lose electrons, and the non-metal ion will gain electrons.
  7. Identify each of the following compounds as ionic or molecular and provide the correct IUPAC name.

    Formula Classification IUPAC Name
    CaF2
    PBr5
    Li2HPO4
    Cr2O3
    Ca(NO3)2•4H2O


    Formula Classification IUPAC Name
    CaF2 ionic calcium flouride
    PBr5 molecular phosphorus pentabromide
    Li2HPO4 ionic lithium hydrogen phosphate
    Cr2O3 ionic chromium(III) oxide
    Ca(NO3)2•4H2O ionic calcium nitrate-water(1/4)

  8. Identify each of the following compounds as ionic or molecular and provide the correct formula.

    IUPAC Name
    		 Classification Formula
    potassium sulfide
    diiodine tetraoxide
    aluminium sulfite
    tin(IV) carbonate
    iron(III) chloride-water(1/6)


    IUPAC Name
    		 Classification Formula
    potassium sulfide ionic K2S
    diiodine tetraoxide molecular I2O4
    aluminium sulfite ionic Al2(SO3)3
    tin(IV) carbonate ionic Sn(CO3)2
    iron(III) chloride-water(1/6) ionic FeCl3•6H2O

  9. Write the formula for sulfuric acid.

    First, write the IUPAC name; as the acid name ends in “ic” and does not start with “hydro,” the IUPAC name must end with “ate”: hydrogen sulfate. Next, balance the charge for hydrogen and sulfate: H2SO4
  10. Four solutions—hydrochloric acid, sodium hydroxide, glucose, and sodium chloride—are tested with red and blue litmus paper and a conductivity metre. What are the expected results?

    Substance Classification Red Litmus
    		 Blue Litmus
    		 Conductivity
    HCl
    NaOH
    C6H12O6
    NaCl

    Substance Classification Red Litmus
    		 Blue Litmus
    		 Conductivity
    HCl acidic red red yes
    NaOH basic blue blue yes
    C6H12O6 molecular red blue no
    NaCl ionic red blue yes
  11. Predict the solubility for the following substances.

    Substance Solubility
    Ag2SO4
    LiOH
    CuCO3
    AuF3

    Substance Solubility
    Ag2SO4 slightly soluble
    LiOH very soluble
    CuCO3 slightly soluble
    AuF3 very soluble

  12. Predict the state for the following substances when they are placed in a beaker of water.

    Substance State
    CrSO4
    Ba(IO3)2
    K3PO4
    PbCL2

    Substance State
    CrSO4 (aq)
    Ba(IO3)2 (s)
    K3PO4 (aq)
    PbCL2
    		 (s)
  13. For each of the following reactions, identify the reaction type and balance the equation.

    1. __KF(l) → __K(s) + __F2(g)
      Type: _______________

      2KF(l) → 2K(s) + F2(g)
      Type: decomposition
    2. __C5H12(l) + __O2(g) → __CO2(g) + __H2O(g)
      Type: _______________

      C5H12(l) + 8O2(g) → 5CO2(g) + 6H2O(g)
      Type: hydrocarbon combustion
    3. __Mg(s) + __HCl(aq) → __H2(g) + __MgCl2(aq)
      Type: _______________

      Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq)
      Type: single replacement
    4. __BaCl2(aq) + __Li3PO4(aq) → __LiCl(aq) + __Ba3(PO4)2(s)
      Type: _______________

      3BaCl2(aq) + 2Li3PO4(aq) → 6LiCl(aq) + Ba3(PO4)2(s)
      Type: double replacement
    5. __P4(s) + __Cl2(g) →__PCl3(s)
      Type: _______________

      P4(s) + 6Cl2(g) → 4PCl3(s)
      Type: formation14.
  14. For the balanced equations from a and c of question 13, represent them using a ball and stick model.



  15. Predict the products, write a word equation, and write a balanced chemical reaction equation for each of the following.

    1. Lithium bromide decomposes.

      lithium bromide → lithium + bromine
      2LiBr(s) → 2Li(s) + Br2(l)
    2. Aqueous aluminium chloride reacts with aqueous potassium phosphate.

      aluminium chloride + potassium phosphate → potassium chloride + aluminium phosphate
      AlCl3(aq) + K3PO4(aq) → 3KCl(aq) + AlPO4(s)
    3. Chlorine gas is bubbled through a solution of nickel(III) bromide.

      chlorine + nickel(III) bromide → bromine + nickel(III) chloride
      3Cl2(g) + 2NiBr3(aq) → 3Br2(l) + 2NiCl3(aq)

    4. Acetylene (C2H2(g)) undergoes complete combustion.

      acetylene + oxygen → carbon dioxide + water vapour
      2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
    5. Zinc reacts with oxygen gas.

      zinc + oxygen → zinc oxide
      2Zn(s) + O2(g) → 2ZnO(s)
  16. What is the amount in moles of a 25 g sample of potassium oxide?

    Write the chemical formula for the substance and determine its molar mass.


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    List the variables.

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    Identify the correct formula and rearrange if necessary.

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    Substitute the values into the formula.

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    Calculate the answer.

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  17. What is the mass in grams of a 3.25 mol sample of ammonia, NH3?

    Write the chemical formula for the substance and determine its molar mass.

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    List the variables.

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    Identify the correct formula and rearrange if necessary.

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    Substitute the values into the formula.

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    Calculate the answer.

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  Unit B Project

Complete the following Unit B Project to wrap up this unit. You will find a project like this one at the end of every unit in the course. These projects are meant to help you put the concepts you have learned in the unit together. There are two options for this project. Please choose only one to complete. Once you have chosen the one you wish to complete, please make sure you read the instructions carefully and follow the rubric. Make sure you ask your teacher if you have any questions.