Purpose: To observe the difference between chemical and physical changes. Materials:
* Hot plate
* Evaporating dish
* Ammonium hydroxide
* Watch glass
* Paper towel
* Alka-Seltzer tablet
* Copper II sulfate
* Lead II nitrate
* Goggles were worn.
* Aprons were worn.
* Lab station was cleaned up directly following experiments. * Hands were washed after experiments.
* No eating or drinking took place in the lab.
* Experiments were not conducted alone.
* Experiment 1: Put a small amount of water into the evaporating dish. Dissolve a small amount of salt in the water. Put the evaporating dish on the hot plate and heat slowly (level 5) until all of the water has evaporated. Record your observations on the chart. * Experiment 2: Take the candle that your group was given and light it. Observe the candle for a couple of minutes and record your observations on the chart. * Experiment 3: Place five drops of Ammonium hydroxide to the watch glass. Add two drops of Phenolphthalein. Record your observations on the chart. * Experiment 4: Get a paper towel and tear it into 20 pieces. Record your observations on the chart. * Experiment 5: Put a small amount of cornstarch into a cup. Add a small amount of water to the cornstarch. Add two drops of iodine to the cup. Record your observations on the chart. * Experiment 6: Put a little bit on water into a cup. Add half of an alka-seltzer tablet to the water. Record your observations on the chart. * Experiment 7: Put three pipets full of milk into the watch glass. Add two pipets full of vinegar to the milk. Observe for several minutes. Record your observations on the chart. * Experiment 8: Put five mL of Copper II sulfate into a cup. Add five mL of lead II nitrate to the cup. Record your observation on the chart.
Experiment number| Observations| Physical Change or Chemical Change?| 1| The water formed bubbles and began to evaporate. The salt started forming into clumps around the rim of the top of the water. The salt continued to clump together throughout the bowl as the water evaporated and the water level lowered. When the water completely evaporated all of the salt was in clusters throughout the bowl. | Physical Change| 2| The candle was lit and the wick turned black to indicate it was burning. The wax surrounding the wick began to melt and form a puddle. After burning for a few minutes the puddle grew. | Chemical Change (burning wick)Physical Change (melting wax)| 3| The ammonium hydroxide was clear when placed in the watch glass. Originally, when the Phenolphthalein was added it turned a murky white color. Ms. Steinhauser explained how that was not supposed to happen so the ammonium hydroxide was replaced and when Phenolphthalein was added to the new ammonium hydroxide it changed to a purple-ish color. | Chemical Change| 4| When the paper was ripped nothing changed except how many pieces of paper there were and the surface area of each piece. A noise was made but nothing else happened. | Physical Change| 5| When iodine was added to the cornstarch it turned to a blue-ish black color. This happened to signify that the cornstarch is, in fact, a starch.| Chemical Change| 6| The alka-seltzer tablet was added to the water and began to dissolve. It bubbled and the surrounding area turned white from the alka-seltzer dissolving. The bubbles indicated the chemical change occurring in the alka-seltzer. | Chemical Change| 7| The vinegar, when added to the milk, separated with the milk because milk is a base and vinegar is an acid. The milk was curdled because of the vinegar being added to it. | Physical Change| 8| When lead II...