5. Soluble or Insoluble?

We say a material or substance is soluble in water when it completely dissolves in a liquid.

Now, let us do an activity to understand this better.

 

Step 1: Take a spoonful of sugar and a glass of water.

 

Step 2: Take some sand and a water-filled glass.

 

 
Step 3: Mix the sugar and sand with the water in their respective glasses.
 
Step 4: Stir it for a few minutes and observe what is happening.

 

We can see that the sugar has disappeared or dissolved in water completely. On the other hand, the sand does not dissolve in water. As a result, the sugar substance is soluble, while the sand is referred to as an insoluble substance.

 

Example for soluble substance: Sugar, salt, washing powder, tablets

Example for insoluble substance: Chalk powder, sand, sawdust

 

Now, we have a better understanding of soluble and insoluble after performing solids experiments.

Yeah, liquids dissolve in water, but not all liquids.

 

Let us now conduct one experiment to decide which liquids dissolve in water and which do not. 
 
Step 1: Collect some lemon juice, vinegar, kerosene and coconut oil samples.

 

Step 2: Fill four vessels with half-filled water.

 

Step 3: Pour the four liquids into each of the four vessels separately.
 
Step 4: Stir it and let it be for a few minutes.
 
We can now see that the bottle containing lemon juice and vinegar has disappeared or dissolved in water. On the other hand, coconut oil and kerosene did not dissolve.

 

As a result, we will tabulate the findings from the previous two tasks.

 

 

Now, we know that some liquids completely dissolve in water, others do not mix with water; and when left alone for a while, they form a separate layer as shown below:

 

 
So far, we have experimented on solids and liquid to find soluble and insoluble with water. But, what about gas?