EXAMSHARE

Western Delta University, Oghara Delta State

department of basic and industrial chemistry
college of natural and applied sciences
western delta university

first semester examination 2022/2023 session

CHM101 - general chemistry I time: 2hrs: 30mins

attempt FOUR questions only

  1. Question 1

    1. State Daltons atomic theory and its modifications (8 marks)
    2. Define:
      1. atom
      2. molecule
      3. ion
      (3 marks)
    3. Briefly describe any three quantum numbers (6.5 marks)

  2. Question 2

      1. A compound is found to contain 26.56% potassium, 35.41% chromium, and the remainder oxygen. Find its empirical formula (K=39, Cr=52, O=16) (4 marks)
      2. Determine the molecular formula of the compound with an empirical formula of CH and a formula mass of 78 (C=12, H=1) (2 marks)
    2. Write the electronic configuration of the following:
      1. Ca
      2. Ca2+
      3. Zn2+
      (4.5 marks)
    3. Consider the equation CuO + Zn → ZnO + Cu
      1. Write the oixdation and reduction half reaction (4 marks)
      2. Identify the oxidizing and reducing agents (3 marks)

  3. Question 3

      1. Balance the redox reaction in an acidic medium Cr2O72+ + Fe2+ → Cr3+ + Fe3+ (8 marks)
      2. Identify the oxidizing and reducing agent (2 marks)
    2. Calculate the oxidation number of
      1. Cr in K2Cr2O7 (2.5 marks)
      2. S in Na2SO4 (2.5 marks)
      3. Mn in KMn04 (2.5 marks)
      And hence the name of each compound

  4. Question 4

    1. Calculate the vapour pressure of a perfect solution of 95.0g of glycerine (C2H5OH, 92.1g/mol) in 190.0g ethanol (C2H5OH, 46.0g/mol) at 40°C. Given P0ethanol at 40°C is 135.3 torr. The glycerine is non-volatile at this temperature (9 marks)
    2. Calculate the freezing point of an aqueous of sucrose whose composition is 25.0g C12H22011 in 100.0g H20. Given freezing ppoint of H20=0.0°C, Kr (water)=1.860cm-1, C=12, O=16, H=1 (8.5 marks)

  5. Question 5

    1. Define acid and base according to:
      1. Arrhenius (1.5 marks)
      2. Lewis (1.5 marks)
    2. Write short notes on
      1. Normal salt (1.5 marks)
      2. Acid salt (1.5 marks)
      3. Complex Salt (1.5 marks)
      1. Comment on five (5) essential postulates of kinetic theory of ideal gases (5 marks)
      2. State with equations three (3) laws governing the ideal gas behavior (3 marks)
      3. List and explain four (4) factors that affect the rate of chemical reaction. (2 marks)

  6. Question 6

    1. State the first and second laws of thermochemistry (4 marks)
    2. Calculate the pressure exerted by 1 mole of water in 20L at 27°C using:
      1. the ideal gas law
      2. van der Waals equation (Values for van der Waals constants a and b for water vapour are 5.464 L2atm.mol-2 and 0.03049 Lmole-1 respectively)
      (4.5 marks)
    3. Give two reasons why gases deviate from ideal behavior particularly at low temperatures and high pressures (3 marks)
    4. Complete the following nuclear reactions equation
      1. 2211Na + 42He → 2612Mg + ? (1.5 marks)
      2. 22286Rn → ? + 2612He (1.5 marks)
      3. 13153I → ? + 0-1e (1.5 marks)
      4. 2211Cl + 10n → 11H + ? (1.5 marks)