Which freezes quicker, hot or cold water?

Introduction

This experiment uses a DrDAQ with external temperature probes to monitor the freezing of two samples of water at different temperatures. The results from this experiment will then show whether the initial temperature of water affects its freezing rate.

It is suitable for ages 14+ and requires some knowledge of the processes involved in state changes of liquids.

Equipment required

• DrDAQ data logger connected to a PC running PicoLog
• Two DrDAQ external temperature probes (Part no DD100)
• Containers that can hold at least 300 ml of water
• A kettle
• A freezer

If the freezer is more than 2 m away from the DrDAQ then you may also require one or more 5 m sensor extension cables (Part no EL032).

Experiment setup

The experiment can be run in one of two ways and both are explained in further detail below:

The two samples can be frozen at different times. The amount of water, container and freezer must be the same.
The two samples can be placed in the freezer at the same time, with identical containers. This makes use of both external sensor connectors and ensures that the freezing conditions for both samples are identical.

Monitoring a single sample

Fill a container with 200 ml of tap water. Obviously the more water used the longer the experiment will take but the amount should remain constant for all future samples.

Insert an external temperature probe into the water.

Make sure the temperature probe isn't touching the side of the container and is fully submerged in the water.

Start running the PicoLog software and check the temperature reading is sensible.

Configure PicoLog to record a sample every 15 seconds for 2000 samples.

Place the sample in the fridge and carefully feed the cables for the temperature sensor out the edge of the door without pulling the sensors out of the cups.

When repeating this experiment for the other samples it is important you use the same amount of water, same container and the same freezer.

Monitoring two samples

Fill two containers, one with 200 ml of tap water and another with 200 ml of heated water (approx 40 °C) . Obviously the more water used the longer the experiment will take but the amount should remain constant for all samples.

Insert an external temperature probe into each container. Making sure the temperature probes aren't touching the side of either container and are fully submerged in the water

Make sure each channel is labeled to remove any confusion with the results.

Start running the PicoLog software and check the two temperature readings are sensible.

Configure PicoLog to record a sample every 15 seconds for 2000 samples.

Place the samples in the fridge and carefully feed the cables for the temperature sensors out the edge of the door without pulling the sensors out of the containers.

Carrying out the experiment

Start PicoLog collecting data and display the recorded data using the graph function in PicoLog. Check to make sure that the temperature of the samples start to decrease. The experiment will be finished once the temperature of both samples has levelled off – this was –11 °C in the freezer we used.