Unit Conversion Review & Sodium Chloride Lab (Sept. 16, 2009)

In today's class, we began by reviewing the worksheet on Unit Conversions. By just going over 3 small examples as a class, all students were able to easily learn the method. One example that we did as a class is :

Change 120 kg to mg

120 kg x 1000 g/1 kg
= 120 000 g x 1000/ 1 g
= 120 000 000 mg


After Digesting all that information, 5 groups were assigned to a desk at the back to do their Sodium Chloride Lab. The purpose of that lab is to see how much salt we could dissolve in 200 mL of water. Below is a list of the steps we took :

1) By measuring 10 mL of water, we slowly poured it into a 50 mL beaker; then collected sodium chloride with a scoopula, added it to the water and began stirring with a stirring rod until if stopped dissolving and the first salt crystals began appearing on the bottom of the beaker.

2) To record our data on our worksheets, we had to see how many grams of salt was gone from the number we started off with.

For example, in my group we started off with 10.00 g of salt on the weight paper which was laid out on top of the electronic scale, which literally showed that we specifically had the exact amount. On the first step we had a total of 0.31 g dissolved into our water, so that's what we recorded.

We then cleaned out the beaker, added 20 mL of water and added even more salt until it got dissolved.

3) Afterwards, after recording our data, cleaning out the beaker, we then moved onto adding 30 mL of water and added even more salt than before till it all got partially dissolved.

4) Finally, the last step of the procedure; clearly finished doing the first two things, we then added 40 mL of water and kept adding salt till we noticed salt crystals were beginning to appear on the bottom of the beaker.

(Rachelle Flores' blog entry)