Honors Chemistry - Heating Curve of Water

Experiment Directions

1. Fill a 1000-ml beaker with tightly packed ice.
2. Place the beaker on a hot plate.
3. Set up a ringstand with a thermometer to sit in the ice, allowing temperature reading without holding it.
4. Turn the hot plate to the highest setting (10).
5. Record temperature every minute until water boils.
6. Estimate the volume of liquid water in the beaker after melting.

Data Collection

• Use Google Sheets to create a data table of time (minutes) vs. temperature (°C).
• Create a graph with time as the x-axis and temperature as the y-axis.

Questions and Observations

General Trends

• Increased heat energy over time results in a constant temperature rise with few plateaus.
• Temperature stays around 0°C until approximately 15°C.
• Takes about 40 minutes to reach boiling at 100°C.

Observations at Key Temperatures

• 0°C: Little to no heat energy observed.
• 100°C: Maximum heat energy observed in the experiment.

Atmospheric Pressure Variations

1. High Atmospheric Pressure
   • Higher boiling point due to increased energy needed to match environmental vapor pressure.
2. Low Atmospheric Pressure
   • Lower boiling point, needing less energy.

Alternative Substances

• Different substances may have different phase change temperatures, altering the graph's appearance.

Volume and Mass

• Liquid water volume: 800 mL.
• Water mass: 800 g.

Calculations

• Moles of water calculation pending.
• Heat calculations using known values:
  • Heat of fusion (ΔHºfus) = 6.01 kJ/mol
  • Heat of vaporization (ΔHºvap) = 40.7 kJ/mol
  • Specific heat (c) of liquid water = 4.184 J/gºC

Energy and Power Calculations

1. Total Time
   • Calculate minutes taken to boil ice.
2. Seconds Calculation
   • Convert minutes to seconds.
3. Hot Plate Power
   • Determine power output in Watts.
4. Hot Plate Heat Energy Output per Minute
   • Calculate kJ given off by hot plate per minute.

Discrepancies in Energy Use

• Possible reasons why observed heat energy is not equal to hot plate output:
  1. Heat lost to surroundings.
  2. Inaccuracies in temperature measurement.
  3. Incomplete transfer of heat from hot plate to water.