DIY Ice Cream

Let's make ice cream in a plastic bag—just for science! This delightful and delicious food science project explores the concept of freezing point depression.

Important Note: Prior to using any of the products mentioned, it is highly recommended to thoroughly read and understand all safety precautions associated with each product. It is also strongly advised to perform a patch test before proceeding with usage.

Please be advised that this guide is intended for informational purposes only and APC Pure cannot accept any responsibility for the outcome of any usage based on this guide.

Here are the materials you'll need:

• Milk
• Heavy whipping cream
• Sugar
• Vanilla or vanilla flavouring
• Table salt or rock salt
• Ice (use Distilled Water and freeze)
• Medium-sized Ziploc bag
• Large-sized Ziploc bag
• Thermometer
• Measuring jars and spoons (choose larger-sized jars)
• Jars and spoons for enjoying your treat (choose larger-sized jars)

Step 1: In the medium-sized Ziploc bag, combine 1/4 cup sugar, 1/2 cup milk, 1/2 cup whipping cream, and 1/4 teaspoon vanilla. Seal the bag securely. Place two jars filled with ice into the large-sized Ziploc bag.

Step 2: Use a thermometer to measure and record the temperature of the ice in the large bag. Add 1/2 to 3/4 cup of salt to the bag of ice. Place the sealed medium-sized bag inside the large-sized bag containing ice and salt. Seal the large-sized bag securely.

Step 3: Gently rock the large bag from side to side. It's best to hold it by the top seal or use gloves or a cloth between the bag and your hands, as the bag will be cold enough to harm your skin. Continue rocking the bag for 10-15 minutes or until the contents of the medium-sized bag have solidified into ice cream.

Step 4: Open the large-sized bag and use the thermometer to measure and record the temperature of the ice/salt mixture. Remove the medium-sized bag, open it, and serve the contents into jars with spoons. Enjoy your homemade ice cream!

How does this experiment work?

When ice melts, it absorbs energy to transition from a solid to a liquid state. By using ice to cool the ingredients for ice cream, the energy is absorbed from the ingredients and the surrounding environment.

Adding salt to the ice lowers its freezing point, requiring even more energy to be absorbed from the environment for the ice to melt. As a result, the ice becomes colder than before, leading to the freezing of your ice cream mixture.

The sodium chloride (salt) causes the ice to absorb more energy from the environment, making it colder. While it lowers the point at which water will re-freeze into ice, you cannot add sodium chloride to very cold ice and expect it to freeze your ice cream or de-ice a snowy pavement since water needs to be present. This is why NaCl isn't used for de-icing sidewalks in extremely cold areas.