Heating Curve for Water
The purpose of this experiment is to make a heating curve for water, to determine the boiling point, to calculate the amount of heat required to heat the water to boiling and the amount to boil it all to steam.
1. Fill 1 L beaker with 500 ml of hot water. (If a beaker of water is already present at your place, use it. Measure the temperature. The water must start out no lower than about 50o C.)
2. Record the approximate volume by reading the beaker and record.
3. Place beaker on hot plate Stir with stir rod. Measure temperature with thermometer every thirty seconds, recording the time and the temperature in an appropriate, neatly labeled and titled, table on a completely separate piece of paper.. Also record observations.
4. When the water boils, LET IT BOIL FOR AT LEAST 5 MINUTES and record the temperature, at 30 second intervals. Then turn the hot plate off.
5. Use the tongs to place the beaker of water on the counter. Leave for the next class.
Graph the data neatly on graph paper using pencil, units, labels, title, and appropriate scale.
Title the graph: Heating Curve for Water. Do not connect any dots. We will do that in class tomorrow. Label the boiling point on the Y axis.
Volume of water:___________________
Time Temperature Time Temperature Time Temperature
Calculations: (Be sure to use units on all values and in all calculations).
Make a label for each calculation then show the calculation:
Conversion of volume of water to mass.
Convert the volume of water to mass using the density of water.
Amount of heat required to heat the water to boiling.
Calculate the amount of heat that was required to heat the water up to the point at which boiling began using q = mass x sp. ht. x DT
Conversion of mass of water to moles
Convert the mass of water to moles.
Amount of heat it would take to boil all of the water.
Calculate the amount of heat it would have taken to boil all the water away using
the molar heat of vaporization and the moles of water.
Turn in: (All should be done in ink, except for graph.)
Data Table with observations.
Data Analysis: Graph, Calculations.
Questions: Write out the questions then answer:
1. What is happening to the water molecules along the rising portion of the curve?
2. What is happening to the water molecules along the horizontal portion of the curve?
3. In which portion(s) of the curve is kinetic energy increasing?
4. In which portion(s) of the curve is potential energy increasing?
5. Has all of the heat generated by the hot plate been accounted for? Explain.