Question

Dater Name Part 5: Specific Heat of Water 

For such a small molecule, water has a very high specific heat. This means it takes a lot of energy to raise the temperature of water. Another important property is the range of temperature for which water remains a liquid. When water evaporates, like from sweat, it also removes a lot of heat from our body. Using the data below, create a graph to demonstrate the heating curve of water. The water starts out as ice and is heated until it is all water vapor. When you are finished with the graph, label the areas on the graph as: ice, water, steam, melting, or evaporating. Don't forget to give it a title and completely label the axes. Then answer the questions below

1. At what temperature does ice melt? How do you know? 

2. At what temperature does water boil? How do you know? 

3. Why doesn't the temperature of the water change while the ice is melting or boiling? (what is happening to the heat energy?) 

4. How does water's specific heat relate to its usefulness for life? (give as many examples as possible)

Answer 1

Prepare a plot of degree Celcius vs minutes as shown below.

Plot of degree Celcius vs minutes 140 melting 120 100 ice vapor 60 degree Celcius 40 Se ries1 20 water 20 10 0 40 20 40 Minutes

1. Ice melts at 0ºC. The flat plateau around 3-6 minutes indicates the melting of ice. Melting is a phase change where ice changes from the solid to the liquid form at a particular temperature. The plot of temperature vs time shows a flat region parallel to the time axis indicating that the temperature remains constant and hence, this region indicates the melting of ice.

2. Water boils at 100ºC. The flat plateau around 26-33 minutes indicates the boiling of water. Boiling, like melting, is a phase change where the temperature remains constant over time.

3. Melting of ice and boiling of water are phase changes and takes place at a particular atmospheric pressure (usually 1 atm) and at a particular temperature. Infact, the melting point and the boiling point are dependent on the atmospheric pressure. The substance changes from the solid to the liquid state or from the liquid to the vapor state at these temperatures. Since the atmospheric pressure remains unchanged, the melting and the boiling points do not change during melting or boiling.

4. The high specific heat of water is highly advantageous.

a) Water can stay in liquid form over a wide range of temperatures. It takes high energy to vaporize water and under normal conditions, such high energy is not easily available and hence, water stays in the liquid form.

b) It is due to the high specific heat of water that water can absorb a large amount of heat and this heat is removed from the body during sweating.

c) Water is used as a coolant in car radiators. Due to the high specific heat of water, water can absorb a large amount of heat and cools the engine components.

d) Due to the high specific heat of water, aquatic animals can survive easily in sub-zero temperatures.