Questions (Clickers)

1
Questions (Clickers)

• If you were interested in disrupting the
  noncovalent interactions between water molecules
  in ice you could
• Shine light on the ice.
• Stick the ice in a freezer.
• Hit the ice with a hammer.
• Add heat to the ice.

2
Questions (Clickers)

• When heat is added to liquid propane,
  (CH3CH2CH3), it warms until reaching the boiling
  point, and then changes into a gas. Which of the
  following statements most accurately describes
  what is going on
• The added kinetic energy is causing the carbon
  and hydrogen atoms in propane to separate from
  one another.
• The added kinetic energy is causing the
  disruption of both hydrogen bonds and London
  dispersion forces between the propane molecules.
• The added kinetic energy is causing the
  disruption of the London dispersion forces
  between the propane molecules.
• The added kinetic energy is causing the propane
  to change into methane gas.

3
Questions (Clickers)

• When heat is added to liquid ethanol, (CH3CH2OH),
  it warms until reaching the boiling point, and
  then changes into a gas. Which of the following
  statements accurately describes what is going on
• The added kinetic energy is causing the carbon
  and hydrogen atoms to separate from one another.
• The added kinetic energy is causing the
  disruption of both hydrogen bonds and London
  dispersion forces between the ethanol molecules.
• The added kinetic energy is causing the
  disruptions of the London dispersion forces
  between the ethanol molecules.
• The added kinetic energy is causing the ethanol
  to change into methane gas and water vapor.

4
Questions (Clickers)

• Both propane (M 44 g/mol) and ethanol (M 46
  g/mol) have comparable molecular weights. Which
  do you predict has the higher boiling point?
  Explain why.
• They should have similar boiling points.
• The ethanol should have the higher boiling point.
• The propane should have the higher boiling point.
• It is hard to tell without doing the experiment.

5
Questions (Clickers)

• When the ice melts from the surface of a pond on
  a warm spring day, this change is
• spontaneous
• nonspontaneous

6
Questions (Clickers)

• When the ice forms on the surface of a pond on a
  cold winter day, this change is
• spontaneous
• nonspontaneous

7
Questions (Clickers)

• Before going on a picnic on a hot sumer day, you
  stopby the store and pick up a block of dry ice,
  CO2(s).
• In terms of ?H alone, is the sublimation of dry
  ice
• Spontaneous
• Nonspontaneous

8
Questions (Clickers)

• Before going on a picnic on a hot sumer day, you
  stopby the store and pick up a block of dry ice,
  CO2(s).
• In terms of ?S alone, is the sublimation of dry
  ice
• Spontaneous
• Nonspontaneous

9
Questions (Clickers)

• Before going on a picnic on a hot sumer day, you
  stopby the store and pick up a block of dry ice,
  CO2(s).
• At 50C (This is one hot day!!) the ?G for the
  sublimation of dry ice as a
• negative value.
• positive value.

10
Questions (Clickers)

• You planning to do some surgery on your kitchen
  table and know that you need to sterilize your
  instruments by heating them to 120C. You rummage
  around in the kitchen cupboards and find a
  pressure cooker that can heat water to a pressure
  of 1.4 atm. Will this be sufficient for
  sterilizing your instruments? (You may use Table
  5.6 in your book to answer this question see the
  previous slide.)
• Yes
• No
• Explain you answer.

11
Questions (Clicker)

• Pentanoic acid and 1-pentanol have the same
  number of carbon atoms. Which one is expected to
  have the higher solubility in water? Explain.
• Pentanoic acid
• 1 Pentanol
• Neither