SEPARATING SOLUTIONS 🔮💎

Separating Solutions | Mixing and Separating

Aim: To seperate a solute from a solvent in a solution using evaporation.

Equipment: Copper sulfate solution (for this experiment, we substituted it for salt) 250mL beaker, heatproof mat, gauze mat, evaporating dish, bunsen burner, and tripod.

Method:

• Set up the bunsen burner, tripod and gauze mat. Don't place the bunsen burner under the tripod yet!
• Add approximately 50mL of hot water to your beaker and place it on top of the tripod and gauze mat. 
• Add enough copper sulfate solution or salt to quarter fill the evaporating basin, along with approximately 50ml of water. We also used a drop or two of food colouring but this is optional.
• Carefully place the basin on top of the beaker. 
• Light your bunsen burner. Open the air hole to create a blue flame and gently push the bunsen burner underneath the centre of the tripod.
• Heat the solution until most of the solvent (water) has been evaporated and crystals of the solute (salt) are forming. 
• Turn off your bunsen burner.

Here are some observations we found during the experiment.

After approximately 2 and a half minutes, we saw the water in the evaporating dish start to evaporate because it began to fog at the top and form condensation.

The beaker water began to boil at around 4 minutes. 

At around seven minutes we saw patches of salt that were off-white in colour on the meniscus. 

At twelve minutes, the evaporating dish resembled Creme Brulee because there was a layer of salt on the meniscus. 

At fourteen minutes we added 30grams of salt to the evaporating dish. We could feel a thickened consistency when we stirred it with the glass stirring stick.

By seventeen minutes the beaker water level was at 75mL, 25mL lower than the original level of 100mL. 

Outline two factors that affect the speed of evaporation (i.e how can the speed of evaporation be increased?). 

1. By stirring the liquid, the molecules in it receive the required amount of energy from the temperature to escape the liquid and evaporate faster.

2. A larger surface area means more liquid is exposed to the air at one time and as a result, will evaporate quickly. For example, a puddle of water will evaporate faster than a bucket of water because the puddle is being exposed to the air more. 

Below is a Google Slide I made displaying diagrams and images of what the experiment will look like.