Separating rock salt

Summary

The video demonstrates how to separate salt from sand in a rock salt mixture. First, the rock salt is crushed to break down large salt crystals. Next, the mixture is stirred in water, allowing the salt to dissolve while the sand remains insoluble. The solution is then filtered, leaving the sand behind. Finally, the salt solution is evaporated by heating, causing the water to evaporate and leaving behind salt crystals. The experiment successfully separates the salt from the sand using basic laboratory techniques such as filtration and evaporation.

Takeaways

• 🔨 The experiment involves separating salt from sand in a mixture of rock salt.
• 🧂 Rock salt is a mixture of salt and sand, used on roads in winter to melt ice and improve grip.
• 🧹 Step 1: Crush the rock salt with a mortar and pestle to break down large salt crystals, making them easier to dissolve.
• 💧 Step 2: Add the crushed rock salt to water and stir to dissolve the salt while leaving the sand undissolved.
• 🌡️ The sand is insoluble, so it settles at the bottom of the beaker, while the salt dissolves in the water.
• 🧪 Step 3: Filter the mixture using filter paper to separate the sand from the salt solution.
• 🔍 After filtering, the sand remains in the filter paper, and a salt solution is collected in the beaker.
• 🔥 Step 4: Use evaporation to separate the dissolved salt from the water by heating the solution in an evaporating basin.
• ⏳ As the water evaporates, salt crystals begin to form in the evaporating dish.
• 🎯 The experiment successfully separates the sand and salt, leaving sand in the filter paper and salt crystals in the evaporating dish.

Q & A

What is rock salt and what is it used for?

Rock salt is a mixture of salt and sand, used to melt ice on roads in winter and improve traction, making it less likely for cars to crash.

Why is the rock salt mixture crushed with a mortar and pestle?

The rock salt mixture is crushed to break down large salt crystals into smaller ones, which helps them dissolve more easily in the next step.

What happens when the crushed rock salt is added to water?

When the crushed rock salt is added to water, the salt dissolves, but the sand, which is insoluble, settles at the bottom of the beaker.

What is the purpose of stirring the rock salt mixture in water?

Stirring the mixture helps the salt dissolve more completely, leaving the sand undissolved at the bottom of the beaker.

How is the sand separated from the salt solution?

The sand is separated from the salt solution by filtering the mixture through filter paper. The sand stays in the filter paper, while the dissolved salt passes through.

Why is evaporation used in the final step of the experiment?

Evaporation is used to separate the dissolved salt from the water, leaving behind dry salt crystals once the water evaporates.

Why is only a small amount of salt solution used in the evaporating basin?

A small amount, about 10 milliliters, is used so that the water evaporates quickly, speeding up the process.

What is the role of the Bunsen burner in the evaporation step?

The Bunsen burner heats the salt solution in the evaporating basin, causing the water to evaporate and leaving behind the salt crystals.

How do you know when to stop heating the solution in the evaporation process?

Heating is stopped when salt crystals begin to form in the evaporating basin, indicating that the water is almost fully evaporated.

What are the final products after completing the experiment?

The final products are dry salt crystals in the evaporating basin and sand collected in the filter paper, successfully separated from each other.