Density, Solubility, Mass when a sample undergoes a physical change

This post includes 3 BIG IDEAS related to our study of matter.

1) Many 7th graders defined matter originally as something that has mass and takes up space. Density is a way to compare those properties in a convenient value. Mass is reported as the mass of a unit volume. Since we have been using the gram for our mass unit and the cubic centimeter for our volume unit, the density units are written as g/cm3. The reported density means that if you took 1 cm3 of a substance, that sample would have the mass of grams indicated. Density is a characteristic property of pure substances. Density is affected by temperature.

2) Students were to dissolve sugar (sucrose) in 100 ml of water. The assignment included keeping track of how much sugar was added. Students were to stop when they thought no more sugar was dissolving. At this point (when no more dissolved), the solution is said to be saturated. Then, students were to find the density of the resulting solution. Only a sample of the liquid portion was to be used (without any undissolved sugar present).

3) An ice cube was weighed in an airtight sealed jar on a triple beam balance. After the ice melted, the container was wiped free of any external condensation and weighed again.

Data and questions for each measuring activity are linked below. Follow the guidelines answering questions and making graphs. Be sure to make digital and print copies and back-up your work:

water any volume  water 100 ml

density of clay  Sugar solution density

mass of melting ice    ice water mass

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