Properties of Water

1. What is meant by saying that water is a polar molecule?

2. What attractive forces account for many of water's properties?

3. Describe adhesion and cohesion.

4. The surface tension of water is created by what type of attractive force?

5. Water sticking to glass is an example of which type of attractive force?

6. Why is water not a good wetting agent?

7. How does water's high surface tension help some insects?

8. Why is the air over the water so much cooler than the air over land?

9. Why can't you see your breath in the summer while you can in the winter?

10. Identify the names and units for each of the variables in the equation Q = mc T.

11. The amount of heat required to raise the temperature of a certain mass of a material by 1^oC is called what?

12. How many Joules of heat are needed to raise the temperature of 30 g of ethanol from 5 to 15^oC?

13. How many grams of sulphuric acid (car battery acid) would show a 25^oC increase when 200 J of heat is added?

14. The addition of 300 J to 100 g of toluene would cause its temperature to increase how much?

15. How much heat would cause the temperature of 500 g of ice to climb from -30^oC to -15^oC?

16. a) What temperature increase would occur when 2550 J are added to 650 g of hexane?
b) If it's final temperature is 28^o C, what would have been its initial temperature?

17. How much heat is needed to raise by 70^oC the temperature of 700 g of water and a 400 g stainless steel pot in which it is sitting?

18. How much heat will be lost from 900 g of water sitting in a 500 g stainless steel pot when they cool 30^oC?

19. What property of water allows it to gain or lose a lot of heat without showing much of a temperature change?

20. Why is the water in our cells a built-in temperature control helping our body stay at about the same temperature all the time?

21. State the Second Law of Thermodynamics.

22. How does this law explain why the air above a large body of cool water does not become very warm even on a hot summer day?

23. How does this law also explain why the air above the same lake in winter is warmer than the air above the surrounding land?

24. Look at Figure 2.3. Why is the collector on the roof? What purpose does it serve?

25. What are water's three phases?

26. At what temperatures does water undergo its phase changes?

27. How many phase changes occur at each of these temperatures?

28. What names are given to water's phase changes?

29. Explain what is meant by the term "heat of fusion."

30. Explain what is meant by the term "heat of vaporization."

31. Why can water gain or lose a lot of heat without showing much of a temperature change?

32. Identify the variables (their names and units) in the equation: Q = mH_fus.

33. How much heat is lost from 150 g of water when it freezes?

34. How many grams of water would lose 500 J when it freezes?

35. Identify the variables (their names and units) in the equation: Q = mH_vap.

36. How many grams of water would need 2 000 J to vaporize?

37. How much heat would be lost from 600 g of steam as it condenses?

38. As exercise increases your body temperature, what cooling process starts?

39. Why does this process cool your skin?

40. What property of ice allows it to float in water?

41. Describe how a lake freezes in winter and the effect that the freezing has on life in the lake.

42. In winter, why is the air near an unfrozen lake warmer than the air further away from it?

43. Look at Figure 2.5. a) Explain the circulation pattern in the water during the late fall.
b) Where might fish be found in the lake during mid-winter?

44. Last winter there was one section of a sidewalk outside of the school that was higher than the rest of the sidewalk.  In the summer it seemed the same as the rest.  Provide a logical explanation.