In science this week we did a lab on observing chemical change. We mixed different liquid chemicals and tested them (in solid form) over a Bunsen burner.
The purpose of the lab was to see what substances are produced when a chemical reaction occurred.
For the entire procedure, refer to page 3-3C: Observing Changes in Matter.
Although we followd the procedue on the page we made a few changes to the chemicals used and the amounts of those chemicals. Instead of using Calcium Chloride (CaCl₂) and Lithium Carbonate (Li₂CO₃), we used Sodium Carbonate (Na₂CO₃) and Strontium Chloride (SrCl₂). We also changed the amounts of those chemicals from 25 mL of each one to 10 mL of each one.
Data and Observations:
In general the two reactants, sodium carbonate and strontium chloride looked the same at the beginning of the experiment. This is a data table of the physical properties that I observed.
Observations of Beginning Reactants
(Sodium Carbonate and Strontium Chloride)
Observations of Changes:
After mixing the two reactants the chemical that formed was milky and white. It was actually two separate materials.We used filter paper to separate the two and found that one was white and powdery while the other was clear like the first two reactants at the start. I think this was a chemical change because a new substance was created, that was made of two different materials.
(The new substance)
(A video of filtering the new substance)
Flame Test Results:
When we passed Sodium Carbonate ions (in powder form) through the Bunsen burner flame, the flame turned bright orange. When we passed Strontium Chloride ions (in powder form) through the Bunsen burner flame, the flame turned slightly orange and mostly red.
The unknown solid that was the product of our reaction turned orange when passed through the flame. It was the same colour as the first flame test, Sodium Carbonate.
(The flame before anything was passed through it)
(The orange flame)
After testing all three solids in the Bunsen burner flame, I believe that the unknown solid was the Sodium that had been mixed into the unknown solid. Since Sodium is a metal, and it turned orange in the flame test, the unknown solid is also sodium because it turned orange too. They were both white powders as well, which means that the plain sodium ions and the unknown powder have both similar chemical and physical properties. This is why I think that the unknown white powder is sodium.
I think that the unknown liquid that had been filtered through the paper was Chlorine, because there had to be a part of Strontium Chlorine in the final substance, and Strontium is a metal. The sodium was already the metal in the substance. This is why I think that the liquid that had been filtered was Chlorine.
In a chemical reaction, the atoms at the start must be there at the end because they can’t disappear. They can change partners though, so I think the Sodium bonded with the Chlorine and the Strontium bonded with the Carbonate. Also, Sodium and Chlorine make each other neutral because their charges equal 0. ( -1 + 1 = 0) Therefore the Strontium and the Carbonate must have also bonded. Their charges match up as well. (-2 + 2 = 0)
(The unknown white powder in the filter)
In conclusion, I think that the final unknown product that we tested was partly Sodium (the powder) and partly Chlorine (the liquid).
During this lab I learned about chemical change and how there was a new substance created when the two substances were mixed. Although the new substance had different physical properties, the atoms were the same because they were there at the start and cannot be destroyed or created.
If I was to do this experiment again, I would make the observation table of the reactants right at the start of the experiment. That was it would be more clear to me and easier to put into my blog. I would also take more photos of the flame test to clearly see both colours. I think since the flame only turned the colour for a few seconds when the compound was passed through, it was difficult to get a clear photo.
During this experiment about chemical change, I learned what happens when two reactants are mixed and how to filter them apart. I also learned how to properly use a Bunsen burner and test a solid. I hope to do more of these types of experiments in the future!