A student performed an investigation to see if certain changes to matter were physical or chemical
changes. When substance undergoes a physical change, the identity of the substance and its physical
properties do not change. However, when a substance undergoes a chemical change, the original
material is converted to a new form of matter.
Investigation 1
A blue candle was placed in its holder and its mass was measured and recorded. The candle was lit and
both light and heat were observed coming from the lit candle. The candle was allowed to burn for 10
minutes. Then, the candle was allowed to cool and its mass was measured and recorded again.
The data were recorded in Table 1.
Table 1
Beginning mass of candle
25.9 grams
Ending mass of candle
24.5 grams
Investigation 2
A small scoop of table salt (about 1 cm3) was added to 40 mL of water and then shaken. The student
observed that the salt granules disappeared after shaking.
Investigation 3
About 1 cm3 of baking soda (NaHCO3) was added to 40 mL of water in a test tube to make a clear
solution. About 1 cm3 of calcium chloride (CaCl2) was added to 40 mL of water in another test tube to
make a second clear solution. The baking soda solution was slowly added to the calcium chloride
solution. A solid (CaCO3) formed and slowly settled to the bottom of the test tube.
Investigation 4
A small piece of magnesium ribbon (Mg) was placed in a test tube. Enough hydrochloric acid (HCl) was
added to cover the piece of magnesium. The bottom of the test tube became warm. Bubbles formed on
the magnesium strip.