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Grade 8 students have recently been studying how different chemicals react with one another. As a demonstration, science teacher, Mr. Murray, created hydrogen from zinc and hydrochloric acid, captured it in a balloon and then ignited the hydrogen in front of a class of very excited Grade 8 students.

Rina ’23 explains how her group studied reaction rates, “I have really enjoyed learning more about chemical reactions this quarter. One of the experiments we conducted was to investigate the changes in the reaction rate of different concentrations of sodium thiosulfate added to a hydrochloric acid constant. This reaction produces sulfur which makes the mixture very cloudy.

“Our investigation required us to vary the concentration of sodium thiosulfate when we dissolved it into the constant 5 ml of hydrochloric acid and timed the result. Firstly, we poured 50 ml of sodium thiosulfate into an empty beaker, placed on top of a piece of paper marked with a cross. We used the cross to help us measure the reaction rate. We added 5 ml of hydrochloric acid and used a stopwatch to time how long it took for the solution to react. The sulfur produced makes the solution increasingly opaque which obscures the view of the cross under the beaker. We stopped timing when the cross disappeared completely.

“We repeated the steps over and over, each time decreasing the concentration of sodium thiosulfate and recording the results. At the end of the experiment, we discovered that as the concentration of sodium thiosulfate is decreased in comparison to the hydrochloric acid constant, the reaction rate correspondingly decreased.”

Mr. Murray said, “The chemical reactions topic gives the students an overview into the various possibilities and properties of different chemicals. Knowing how substances behave in certain situations is an incredibly important lesson for future chemistry courses. Understanding how and why chemicals behave the way they do opens up a range of possibilities in industries such engineering and medicine.”