Science 13

Some students were interested as to why salt was spread on snow-covered roadways. They performed the following experiments to investigate the effects of salt on the freezing and boiling points of water.

Experiment 1

Five solutions of various concentrations of NaCl (sodium chloride) in H2O were prepared. The mass of 20 mL of each solution was measured, and the density of each solution was calculated using the formula: density = mass/volume. The masses were recorded in the Reference Table.

Experiment 2

A 40mL sample of H2O was placed in a beaker with a thermometer and heated until boiling. The temperature at which the water boiled was recorded as the boiling point. The students repeated this procedure for the solutions prepared in Experiment 1.

The boiling points in relation to percent NaCl (by mass) are represented by Figure 1.

Experiment 3

90 grams of H2O (freezing point of 0 C) and 10 grams of NaCl were mixed in a flask containing a thermometer. The mixture was cooled in an ice-bath until ice crystals began to appear. The temperature at which this occurred was recorded as the freezing point.

The students repeated this procedure with varying amounts of H2O and NaCl. All freezing points were recorded in Table 1.