Max Gross Period 5 03/25/11

HOME LAB – GASES

Procedure A

Observations: After the water in the can reached a rolling boil and the can was inverted in a cold-water sauce pan, the can collapsed in.

Explanation: When a can is inverted into a saucepan filled with cold water, it is closed off from the outside air and allowed to cool. The can collapses because the water vapor that is in the can condenses down to a small amount of liquid when it is put in the cold-water pan. The liquid does not fill the can like the water vapor did. Since the vapor condenses into a liquid, not many gas molecules are left to exert pressure outward to balance out the atmospheric pressure. As gas molecules from the atmosphere exert their pressure on the can, it is crushed. So really it is the atmospheric pressure that causes the can to be crushed.

Pictures:

Parent Signature ______

Procedure B

Observations: Big Glass Amount of water Observations Full - After releasing hand, card stuck to mouth of the cup for a split second, then dropped and the water came out - Felt suction from cup of water when inverted with card covering mouth of glass Half Full - After releasing hand, card stuck to mouth of the cup for 2 seconds, then dropped and the water came out - Felt suction from cup of water when inverted with card covering mouth of glass

Small amount of water - After releasing hand, card stuck to mouth of the cup for 17 seconds, then dropped and the water came out - Felt suction from cup of water when inverted with card covering mouth of glass

Paper Cup with Hole in Bottom Full Held finger over hole until turned it over and also released finger from card and card immediately dropped Half Full Held finger over hole until turned it over and also released finger from card and card immediately dropped Small amount of water Held finger over hole until turned it over and also released finger from card and card immediately dropped The result was the same for all paper cup trials.

Explanation: The relationship between pressure and volume is inversely proportional. When the volume is lower, the pressure is higher and when the volume is higher, the pressure is lower. For example in the big glass, when the glass was full (high volume), the pressure was lower, and therefore the card dropped and the water came out almost immediately. Also when the glass had a very small amount of water, the pressure was higher as the card stuck to the cup for 17 seconds before falling and the water coming out.

The equation for this relationship is Pressure x Volume = k a constant. This is known as Boyle’s Law.

The paper cup could not maintain pressure and hold the paper because of the hole in the bottom of the cup. When the hole was covered with a finger, there was enough suction created due to the pressure inside that kept the card on the mouth of the cup. Once the finger was removed from the hole, the card instantly dropped.

Pictures:

Full Glass – card fell and water came out Small amount of water – card stuck in split second for 17 seconds

Paper cup with hole – water released immediately

Parent Signature ______

Directions for written portion: 1. Record all observations. 2. Propose an explanation 3. Include labeled diagrams to help illustrate your explanations and ideas. 4. Include parent signature.