Assignment: 11

  • 1) Predict whether each of these substance would be more soluble in water (polar solvent) or benzene (nonpolar solvent)
    1. Olive oil (non polar)
    2. Ethanol or grain alcohol ( polar)
    3. Table Salt or NaCl (ionic)
    4. Sugar (Polar covalent)
  • 2) Compare the processes that occur when potassium chloride, barium hydroxide and hydrobromic acid (HBr) dissolve in water. Write out the equation and make a sketch of what is happening.
  • 3) What is the expected conductivity of electricity of each of these substances?
    1. Acetic acid (Vinegar)
    2. Butane (C4H8)
    3. Ammonia (NH3)
  • 4) At standard pressure (1 atm) and 0°C, diatomic oxygen (O2) can dissolve in water at a rate of 0.70 g/ 1 L of water. At the same temperature, but at a new pressure of 0.25 atm, how much oxygen can dissolve in water?
  • 5) Calculate mole fraction for each of these solutes and solvents:
    1. 120 g of NH4NO3 in 300 g of water
    2. 25g of Br2 in 150 g of ethanol, C2H5OH
    3. 25g of NaCl in dichloromethane, CH2Cl2
    4. Methanol, Ethanol and water in a solution that is 35% methanol, 40% Ethanol and 15% water
  • 6) Practice calculating molarity:
    1. 875 g of H2SO4 in 2kg of water
    2. Cyanic acid (HCN) in a solution that is 74% HCN by mass
    3. A 26% solution (mass) of potassium carbonate (K2CO3) with a density of 1.09 g/cm3.
  • 7) Predict which compound would depress freezing point the most, and explain why:
    1. NaCl
    2. Glucose
    3. Na2CO3
  • 8) If a solution of MgBr2 in water freezes at -1.28°C, what is the boiling point of the solution?. Assume ideal solution behavior.
  • 9) Explain two major differences between colloids and solutions.
  • 10) How would you prepare a 4.5 m aqueous solution of glycerol (C3H8O3)? Calculate freezing point for this solution. This is often used by scientists to freeze bacteria- why might this molecule be a good choice?