Question

Questions from the book Cat’s Cradle by Kurt Vonnegut.

Cat’s Cradle by Kurt Vonnegut

- In this novel a scientist discovers a new form of solid H2O that is stable at room temperature.

- When a small crystal of this substance is introduced into the ocean it solidifies leading to the end of life on earth.

- The substance is known as Ice-9

Excerpt from the Book

- I closed my eyes

- There was a sound like that of a gentle closing of a portal as big as the sky, the great doors of heaven being softly closed

- It was a great AH-WHOOM.

- I opened my eyes and all the sea was ice-nine

- The moist green earth was a blue white pearl

- The sky darkened. Borassi, the sun, became a sickly yellow ball, tiny and cruel.

- The sky was filled with worms. The worms were tornadoes.

Properties of Ice-9

- Crystalline solid

- Molecules of H2O organized differently than normal H2O

- Melting point is 45.8oC

- A small crystal causes the entire ocean to solidify.

Questions

1. Based on the information given, will ΔGo for the formation of ice-9 from liquid water be (+) or (-)? Explain how you know.

2. Will the entropy, So, for the system increase or decrease for this process? Explain how you know.

3. Based on your answers above, will the enthalpy change, ΔHo be (+) or (-) for the process. Write an equation to support your answer.

4. In the story, the author doesn’t mention any temperature change. Based on your answers above, how would the temperature change in the system? In the surroundings?

5. Does ice-9 have stronger or weaker intermolecular interactions than regular ice? How do you know?

6. Given that the melting point of ice-9 is much higher than that of regular ice, will the ΔHo for the conversion of water to ice-9 be more positive or more negative than the ΔHo for the conversion of water to regular ice? H2O(l) → Ice-9(s)

Calculations

7. If 1.00 mol of water at 0oC were converted to ice-9 what is the minimum quantity of heat that would be released? (The enthalpy of fusion for regular ice is 6.01 kJ/mol)

8. Imagine 1.00 mol of water being converted to ice-9 in an insulated container. Liquid water has a heat capacity of 4.184 J/goC. Make the assumption that ice-9 would not have a heat capacity of more than liquid water. Calculate the temperature change that would have to result from the conversion of 1.00 mol of liquid water at 0oC to ice-9 in an insulated container.

Thank You.

Answer 1

Question 1. The ice 9 is stable at room temperature (solid at 25 ºC) and the melting point is 45.8 oC so the temperature from water which forms ice 9 must be above this temperature (melting point) therefore the transition of liquid to solid water (ice 9) must be in the same direction as usual (cooling direction from higher to lower temperatures), this process is spontaneus because the system is trying to reach the surrounding temperature (room temperature) which is 25 ºC, for that I would expect the ΔGo to be negative, the water is passing to one stage of high energy to another stage with lower energy.

Question 2. the entropy for the system (water) would decrease, for the same reason, the change of state is from a liquid state (above 45.8, more entropy) to a solid state (near 25, less entropy).

Question 3. the enthalpy change must be negative so the free gibb's energy be negative which it makes sense because the liquid state has a higher associated enthalpy than the solid state, therefore the change must be negative.

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