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Questions (Clickers)

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. Questions (Clickers).

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Questions (Clickers)

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  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 ΔH 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 ΔS 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 50°C (This is one hot day!!) the ΔG 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 120°C. 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

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