In this demonstration, warm water is placed in a plastic syringe, the syringe is sealed, and the plunger is pulled back causing the water to boil. The water boils because the action of pulling back the plunger increases the volume, thus decreasing the pressure. The boiling point of a liquid is dependent on the pressure of the system, so a decrease in pressure leads to a decrease in boiling point.
In this demo, a skewer is pierced through a balloon without popping it. The balloon is made from a rubber polymer. The polymer is made of many long, elastic, overlapping chains, very similar to spaghetti. When a skewer pierces the balloon, these chains are stretched and pushed open to make a hole for the skewer and the balloon does not pop. It is important to pierce the balloon near the bottom & top, where the rubber has the least amount of stress. The polymer is more able to stretch and rearrange, allowing the skewer to pass through.
When a marshmallow is placed in a large capped syringe and the plunger is pushed in, the air in the marshmallow contracts from the pressure. Conversely, if the plunger is pulled back, the pressure decreases causing the air in the marshmallow to expand.
Friday November 18, 2011: Casey and Dr. Caran presented a talk to attendees of the Virginia Association of Science Teachers’ Professional Development Institute.
Liquid nitrogen is -196˚C and quickly freezes the ingredients into ice cream. The nitrogen boils out leaving deliciously creamy ice cream. The “fog” that we see is condensed water vapor though, not nitrogen gas.
Sunday August 28 – Wednesday August 31, 2011: Casey presented her chemical demonstrations research at the National ACS meeting.
Friday July 15th, 2011: Casey and Dr. Caran hosted 19 high school teachers and 1 high school senior from around the Commonwealth on for an all day Chemistry Demonstration Workshop.
When water is placed in a balloon, the balloon can be placed over a flame without popping. Water absorbs the heat from the flame, so the rubber of the balloon does not become weak and break like it does with the dry balloon.
Wednesday June 29th, 2011: Casey and Dr. Caran participate in a video shoot involving dry ice and liquid nitrogen demos.
This demonstration makes iron (III) thiocyanate complexes that are deep red in color, resembling fake blood.