The deadly sawmill explosions last year in Burns Lake and Prince George inspired Alex Koenig and Austin Douglas to create a Central Interior Science Exhibition experiment to demonstrate the explosive power of sawdust.
The two Fraser Lake elementary school Grade 7 students connected a four-inch PVC pipe to an air compressor, pored sawdust into the tube and ignited the mixture with a propane torch as the compressed air forced the sawdust out.
Their backyard experiment under parental supervision produced a large plume of fire out of the end of the tube that split down the middle each of their hypothetical estimates of how much material was needed to produce the largest flame. Koenig predicted 24 inches of sawdust was needed for the maximum flame height while Douglas figured a 12-inch pile would get the job done better. As it turned out, an 18-inch pile worked best.
"We thought of this experiment because of the mill fires and we wanted to find ways to prevent it and what caused it," said Koenig. "We found out of you have too much sawdust it would smother the flame and if you had too little it would not create enough big fire."
Douglas said he had to perform the experiment five times and would have repeated the test even more to prove the results, but they ran out of time.
"I learned that sawdust, at any level, is combustible," said Douglas. "No matter how small the flame is, the sawdust will always light on fire. Now, all the mills are having dust cleanouts because of the fires, so that's what got us thinking about it."
Last year, Koenig's Bouncy Balls project earned him a gold medal but he was too young to be eligible for the Canada-wide science fair, which is only open to students in grades 7-12.
Caterpillar-killing compounds, fruit-powered batteries and the use of garlic juice to kill bacteria were among the themes explored in the 37th annual Central Interior Science Exhibition, which involved 150 students from Prince George, Quesnel and Vanderhoof school districts, who worked on 118 projects. The day-long event gave students a chance to win prize money and scholarships and the chance to compete in the Canada-wide science fair in Lethbridge in May.
Brendan Telford, a Grade 7 student at Immaculate Conception school, wanted to know if saltwater or freshwater makes metals rust faster and proved that salt does speed the oxidation process. He dipped copper pennies, brass tubes and chunks of steel into different types of water to test each metal's electrical conductivity and determine how long it takes for rust to appear.
"The metals in the saltwater rusted more than in normal water because saltwater allows more ions into the water, which allows the electric current to flow through the water, adding more oxygen, so you get more rust," said Telford.
"You could sit in a bathtub of distilled water and out a 100-volt current into it and you'd just feel a little bit tingly because distilled water isn't a good conductor. If you put that same current in saltwater, you'd die. The salt adds ions to the water, making a better conductor and as the current passes through it creates oxygen in the water and that causes rust."
Telford tapped into the topic of rust when he left his bike outside despite his parents objections and exposed it to the elements for a few months, leaving him with a rusty chain and rusty pedals, which he had to replace.
Grade 8 student Elizabeth Schulz starting working on her science fair project last summer, after her friends at Fraser Lake elementary complained of swimmers itch, an immune reaction that left itchy red spots on their skin after they took a dip in the pubic beach at Fraser Lake.
Schulz focused on Lymnaea stagnalis, the pond snails that carry the parasites that cause swimmers itch, and experimented with different ways to reduce the snail population. The two most effective methods were using chemicals (copper sulphate) and the scoop-and-scrape method, stirring up the bottom of the pail and then using a fish net to collect the quarter-sized snails.
"Copper sulphate was the most successful overall because within two days I was able to reduce the snail population by 100 per cent," said Schulz. "But the problem with that was it was toxic not only to snails, but would harm the rest of the ecosystem, so my scoop-and-scrape method was a lot safer. I was surprised how effect my methods were."
Brandon Billy and Gavin McDermid, Grade 5 students at Malaspina elementary, found out that four lemons and four tangerines have enough citric acid to power a light bulb, and they were able to get enough electrical charge out of only three limes to light the same bulb.
"The tangerines made the bulb glow the brightest, the limes made it glow the least, and the lemons where right in the middle," said McDermid. "We think one day we can charge an iPod or even charge a whole house with fruit. You'd need about 50 tangerines per room."
There was one unexpected result. The pennies used to conduct the electricity in each piece of fruit came out shiny and clean. "The acid in the fruit takes away the tarnishing," said Billy.
