On April 24th, 2008 Washington University held its annual "Take Our Daughters and Sons to Work" Day (organized by Meredith Lopez, Employee Relations). As part of the activities the Chemistry department sponsored an event entitled "The Chemistry of Fireworks". Over 40 girls and boys aged 8-12 yrs and their parents participated in three sessions. There were two different activities. First the students explored the color of fireworks by performing flame tests. The lab activities concluded with "Fun with Liquid Nitrogen", where the effects of very cold temperatures on various objects was explored.
The Chemistry of Fireworks
Although fireworks were invented over 2000 years ago by the Chinese, the use of colored fireworks is relatively recent. To obtain colored fireworks metal salts are used. Here Amy Walker explains about the history of fireworks.
Students sprayed saturated solutions of metal salts into a flame to find out about the colors of fireworks.
By spraying several salt solutions at the same time, you can make "traffic lights"!
Fun with Liquid Nitrogen
To find out how cold liquid nitrogen is, students touched the floor after liquid nitrogen had been poured on it.
If a flower is put in liquid nitrogen, it gets so cold that it can be shattered.
Just like this!
Liquid is so cold that it makes air denser and deflate balloons!