For the past couple of months in Science we have been learning about chemistry. This has been a pretty big unit that at times has been difficult to grasp different concepts or ideas. Overall this unit has been very fun especially when we get to do experiments in class to demonstrate our understanding. One of the the first things we did in our unit was a mind map to show what we already knew about chemistry, later on we each made one at the end to show what we learned. During this unit we also did a partner project using chemical equations and creating our own experiment.
Mindmap
Our project was based around the question “How can chemical reactions be used to identify the composition of a substance?” For this experiment project I was with Ryan, at first we did quite know what we wanted to test for as there were so many options and endless opportunities. One thing we did know is that we wanted some sort of reaction with a explosion or very visible chemical reaction. After brainstorming for a bit and looking at videos we came across a video from the Crazy Russian Hacker about an experiment called elephant toothpaste. This looked very interesting and we decided that we were going to further our research to better our knowledge of the experiment.
The materials needed for the experiment include:
5p ml of 30% hydrogen peroxide solution
Potassium iodide solution
Dish soap
500 ml graduated cylinder
Googles
gloves
To do the experiment here are the steps:
Put on gloves and safety glasses as hydrogen peroxide is very corrosive.
Pour 50 ml of the hydrogen peroxide solution into the graduated cylinder
Next pour a little dishwashing soap into the hydrogen peroxide, make sure to swirl it around until fully dissolved
Add 10 ml of potassium iodide solution into the dishwashing soap and hydrogen peroxide mixture (DO NOT lean over the reaction as you may get splashed or burned by the chemicals.
Observe the experiment
The instructions are quite easy although we were told that we weren’t allowed to actually preform the experiment instead we told our teacher what to mix for the reaction to occur. The reason for this is because hydrogen peroxide is very dangerous and corrosive and can burn your skin very easily.
Our original idea for a variable we would change and test for a difference was the soap in the experiment. However after talking with our teacher and research further into the experiment we decided instead we would test for oxygen after the experiment was complete. Our question for this experiment was “Can we detect oxygen in elephant toothpaste?”. To test the oxygen we used a match and let it burn down then put it into the elephant toothpaste and if it relights then there is oxygen in it.
Our hypothesis was that there would be oxygen in the elephant toothpaste as there is oxygen in the formula. When testing the experiment our hypothesis was right and the match did relight itself in the elephant toothpaste. The reaction shows the breakdown of the hydrogen peroxide into water and oxygen, this is what forms the foam. This reaction is known as a decomposition reaction because of when the hydrogen peroxide breaks down into other elements or compounds. The potassium iodide is actually not part of the equation because it’s a catalyst which means it helps with the speed of the reaction. Without the potassium iodide you wouldn’t be able to see the reaction because it would be so slow. The dishwashing soap creates bubbles, these bubbles have oxygen in them to help the reaction take place. The equation of this reaction is 2 HO2(aq)->2 H2O(I)
This is a video of us doing the experiment in class and the results of our testing:
Overall this was a super fun project that allowed use to put our own personalized touch on, It also allowed us to demonstrate our understanding of our unit. If I were to do this experiment again one thing I would probably do pile be to prepare myself more for our presentation to the class as we could have had more questions to ask and spark discussion.
Once we finished this project we completed our second mindmap of what we know about chemistry to show our learning and understanding of the unit. This is my mindmap:
