12th Practical Lesson: 1P13 Which can Dissolve More?

Yet another practical lesson and this time, the title of the practical was intriguing, thus we were quite excited to find out more. That day, when we entered the lab, I found that the class was less noisy than usual and I knew they wanted to know more about this practical. As a result, we could get started with this  practical lesson quickly. First, of course there were precautions for us to take and instructions for us to follow and we had to listen carefully to our Science teacher, Mr Low who was explaining some concepts first before starting us on the experiments.

What do we aim to achieve in this practical then? We hope to find out the solubility of different solutes differ in the same solvent. So some food for though before we start, controlling variables. We needed to know how to control variables to start with this experiment. So, controlling variables is to change only 1 variable at a time and keep the other variables constant to ensure a fair test. In this experiment, since we want to find out the solubility of different solutes, the factor or variables we must change is the type of solvent.

What about the other factors to be kept constant? They include:

1. Type of solvent
2. Mass of solute
3. Volume of solute
4. Temperature of solvent

The procedures we need to follow? Well, firstly, we had to measure 20cm³of water, then we had to weigh 1g of common salt using the electronic beam balance and add the common salt to the water. Next, we have to stir and dissolve the common salt in water. If it dissolves, completely, we have to weigh another 1g of salt and add it to the water. We have to continue adding the water until no more of such salt will dissolve anymore. We also have to repeat the following steps with baking soda and iodine crystals.

After the whole experiment, we had to tabulate our results in a table with the type of solute and the maximum amount of it dissolved/g.

So what can we conclude from the above results? We can conclude that of the 3 solutes tested, common salt is the most soluble in water and iodine crystals are the least soluble in water. Thus, different solutes have different solubility in the same solvent. How will I improve the experiment if I could? I will measure the solutes in smaller amounts so that I can get more accurate results.

The next practical lesson will be in the end of June as there are other activities on this day for the following weeks and I will miss the lab dearly. :D

11th Practical Lesson: 1P12 Forming Compounds

We had this practical lesson on the same day as 1P11 but I did not have space to put it in my previous post. We had to cram two practicals in the same day and it was quite a mad rush. As usual, we had to gather our materials first:

1. Magnesium ribbon
2. Iron fillings
3. Dilute sulfuric acid
4. Lead (II) nitrate solution
5. Sodium chloride

Our apparatus include: test tubes, Bunsen burner, evaporating dish, test tube holder and a pair of tongs. There were some things that were aimed to achieve at the end of the practical and we had to take note of them. It was to investigate the formation of these compounds by:

1. Reacting two elements
2. Reacting an element and a compound
3. Reacting two compound

With these aims clear in our minds, we started our experiment. Our first experiment was to hold a magnesium ribbon with a pair of tongs, place it in the Bunsen flame and when the magnesium ribbon catches fire, hold the pair of tongs above the evaporating dish to collect the ashes formed. So what do we see? We see that the ribbon starts to burn and gives off a bright light. This is the natural chemical reaction when magnesium comes into contact with fire. We also had to observe the ashes which were flaky and white in colour after it was burnt.

Next, we had to answer a question on the whether due to the Bunsen flame, a new substance has formed and why it has occurred. My answer was as follows:

Yes. Oxygen has reacted with magnesium under higher temperature and also due to the heat it has broken the chemical bonds between the magnesium ribbon and also, the appearances of the magnesium ribbon has totally changed.

This means that oxygen has reacted with magnesium to create magnesium oxide, the white substance formed. :O

How about reacting an element with a compound? Well, our next experiment tells us more. First, we had to place half a spatula of iron fillings in a test-tube. Next, we had to add dilute sulfuric acid to a depth of about 2 cm and record our observations. My observation was that the mixture started to bubble and there were bubbles of colourless gas rising from the iron fillings. So did it change into a new substance and why so? Well, it has indeed changed into a new substance and of course, the reason is that there was a change in appearance and also that heat was involved to break the chemical bonds and form new ones as well.

Last but not least is to react two compounds.So what do we do? First, we place sodium chloride solution in a test-tube to a depth of about 2 cm and then using a dropper, add lead (II) nitrate solution slowly to the test-tube. you will observe that white precipitate formed.

So what exactly can we conclude from this experiment? We now know how the different compounds are formed. :D

10th Practical Lesson: 1P11 Investigating Mixtures and Compunds

Another Science Practical lesson worth waiting for. Today, we will be exploring compounds and mixtures and of course experimenting with them.


That day, we had some food for thought before we started to gather our apparatus.

• Both sulfur and iron are elements
• When they are mixed, a mixture of iron and sulfur is formed.
• When they are heated together, a compound, iron sulfide is formed

The apparatus we need for the 1st experiment are tripod stand, evaporating dish, glass rod, wire gauze and Bunsen Burner. The materials we require include sulfur powder, iron fillings, filter paper, a piece of paper and a magnet.

We had to place the sulfur powder on a piece of filter paper and observe and describe its appearance. From what I could see, I noted that the sulfur powder is yellow in colour. We then had to wrap one end of the magnet with a piece of paper and observe if the sulfur powder is attracted to the magnet. However, due to the fact that it is not a metal at all, it definitely cannot be attracted by the magnet.

Next, we had to pour some iron fillings on an evaporating dish and observe its appearance which is obviously grey powder and also whether it can be attracted by a magnet. It could be attracted by a magnet due to the fact that it is made up of iron which can be attracted by a magnet and it is a magnetic material.

Following that, we had to mix the two elements together which will give us a mixture. The mixture is yellowish grey with specks of yellow powder. When you put the magnet near to the mixture, what will happen? Well, the magnet will only attract the iron fillings but will not attract the sulfur powder.

The last step is for us to make a compound. How so? First, we had to heat the evaporating dish over the Bunsen Burner until no more changes occur. We had to allow the evaporating dish to cool down. Then, we observed the compound formed and describe its appearances. This time, it became a black solid which was quite interesting and cool too. When we held the magnet close to the compound, it only attracted some of the compound. We found it interesting and asked ourselves why and it was due to the fact that some of the iron fillings properties were lost during the heating process and thus the magnet could only attract some of the compound.

From these experiments, we can conclude that a mixture retains the properties of its constituents while a compound does not. We also had to plot a table and these were the results.

I hope there can be more of such experiments on these interesting compounds and mixtures in the future. :D