NECT Gr 10 Heating and Cooling Curve of Water

Experimental Procedure: Heating Curve of Water
📌 The investigation aims to measure the temperature of water as it melts and is heated to its boiling point, and subsequently cools down.
🌡️ Apparatus required includes ice, a thermometer, a Bunsen burner, a tripod stand, a gauze mat, a beaker, and a stopwatch/cell phone for timing.
💡 The thermometer must be positioned a couple of centimeters above the bottom of the beaker to measure the water temperature, not the flame temperature.
📊 The process involves measuring temperature every one minute and recording the phase of water during the heating process.

Variable Identification and Control
⚙️ The independent variable is the time interval chosen between temperature recordings (set to one minute).
📈 The dependent variables are the temperature of water and the phase of water, both dependent on the time of heating.
🔥 Control variables are crucial, including setting the Bunsen burner flame to a constant rate and ensuring the mass of water remains constant throughout the experiment.

Heating Curve Data Collection (Ice to Boiling)
🧊 At time $t=0$ minutes, the temperature of crushed ice is $0^\circ \text{C}$ and the phase is solid.
💧 During the phase change (melting), the temperature remains constant at $0^\circ \text{C}$ (e.g., at 1 and 2 minutes, the phase is noted as solid/liquid).
📈 After melting, the temperature rises steadily; for example, at 3 minutes it is $1.5^\circ \text{C}$ and at 5 minutes it is $4^\circ \text{C}$.
📊 The recording continues until 35 minutes, providing data points to plot the heating curve of water.

Cooling Curve Procedure
❄️ To measure the cooling curve, the hot water beaker is placed in a trough of crushed ice to ensure a faster cooling rate than cooling in air.
⏱️ The initial temperature at time $t=0$ minutes for the cooling curve was $45.5^\circ \text{C}$.
📉 Readings are taken at one-minute intervals; the temperature dropped to $35^\circ \text{C}$ at one minute.
📝 No phase change (freezing) is expected unless the water is cooled significantly below $0^\circ \text{C}$ using refrigeration equipment.

Key Points & Insights
➡️ Before analysis, ensure the table of results has an appropriate heading and all readings have the same number of decimal places for consistency (e.g., $0.5$ vs $7.5$).
➡️ SI units should only be shown in the column headings, not repeated in every row of the results table for clarity and neatness.
➡️ The experiment emphasizes the constant temperature plateaus observed during phase changes (melting at $0^\circ \text{C}$) as predicted by the theoretical heating and cooling curves of water.
➡️ Students are instructed to work individually to complete the graphs and answer subsequent questions based on the collected data, seeking teacher support only.

📸 Video summarized with SummaryTube.com on Feb 23, 2026, 15:50 UTC