Particle Motion and the states of matter 7th Grade Science

Why would we add salt to the ice on the outside bag to make ice cream? Why would a chef add salt to a pot of water s/he was going to cook pasta in?

Engage! Place one quart sized freezer bag inside of another quart sized freezer bag.  This will prevent any unwanted salt in the mixture. In the inside quart sized bag, measure .5 cup milk, .5 teaspoon of vanilla extract, .25 cup evaporated milk, and 3-6 teaspoons of sugar.  Close the bag, making sure it is well sealed. Take a gallon sized freezer bag and fill it about half way with ice. Add about a cup of either rock salt or any ice-melter you find at a grocery store or gas station. The salt that is sold for home water softening is relatively inexpensive, and totally pure, non-toxic salt. Put the quart sized freezer bag inside of the gallon sized bag.  Seal the gallon sized bag.  BOTH BAGS SHOULD REMAIN SEALED! Knead the ice around the quart sized bag.  Students can work in partners and take turns at this process. Students can knead from 10 – 30 minutes depending on how well they work at it and the consistency that they prefer.

Design an Experiment With your group design an experiment to investigate how the amount of salt in water might affect how water freezes or boils Your investigation should include: Supplies that are easy to access Appropriate measurement techniques Ways to avoid bias and ensure results are reliable A hypothesis Create a poster to display your experiment to your classmates. Include: a pictorial representation of your project At least three colors Contribution from all group members

Compare Leave behind two group members Have your other group members go around to gather information about others’ planned investigations What similarities did you see? What differences? Would their project lead to a reliable answer on how salt effects boiling/freezing point? Why or why not? How does their hypothesis compare with yours?

Draw a model of the molecules of a solid, liquid, and gas in your notes. Talk with your group about how they are different in each state of matter

Video https://www.youtube.com/watch?v=xYU7RSoOZ0U

Heat transfers from areas of high temperatures to areas of lower temperatures Heat transfer in a bathtub occurs form the hot water to the cooler air, to the cooler floor, to the cooler tub sides, and even to the cooler person in the water

So thermal energy (heat) has to do with how particles are moving (kinetic energy) within something And thermal energy (heat) also has to do with the way energy transfers due to the temperature difference between two objects.

Adding salt to water actually increases its boiling point meaning it actually boils slower, but the water gets hotter so the pasta cooks faster. Salt also lowers the freezing point as well so the water would get colder before it became a solid

An exothermic reaction is a reaction in which energy is released An endothermic reaction is a reaction in which thermal energy is absorbed Example: boiling or melting An exothermic reaction is a reaction in which energy is released Examples: condensation or freezing