Solubility and Composition of Chalk

The video explains the solubility of two types of chalk: classroom chalk made of calcium carbonate and sidewalk chalk made of calcium sulfate. Classroom chalk is insoluble in water, meaning it does not dissolve and sinks to the bottom. In contrast, sidewalk chalk is slightly soluble due to its composition as a calcium sulfate dihydrate, allowing a small amount to dissolve in water. The video uses solubility rules and tables to illustrate these concepts.

What is the primary ingredient in classroom chalk?

• Magnesium oxide

• Sodium chloride

• Calcium carbonate

• Calcium sulfate

Why is calcium carbonate considered insoluble in water?

• It sinks to the bottom without dissolving

• It evaporates

• It reacts with water

• It dissolves completely

How can you confirm the insolubility of calcium carbonate?

• By heating it

• By using a solubility table

• By tasting it

• By freezing it

What is the main component of sidewalk chalk?

• Calcium carbonate

• Calcium sulfate

• Sodium bicarbonate

• Potassium nitrate

What does the 's s' notation in the solubility table indicate for calcium sulfate?

• Slightly soluble

• Not listed

• Highly soluble

• Insoluble

What happens when you put sidewalk chalk in water?

• It remains unchanged

• It reacts violently

• It dissolves completely

• A small amount dissolves

What is the term for calcium sulfate with two water molecules?

• Trihydrate

• Dihydrate

• Monohydrate

• Anhydrous

Which type of chalk is more soluble in water?

• Classroom chalk

• Neither is soluble

• Both are equally soluble

• Sidewalk chalk

What is the main difference in solubility between classroom and sidewalk chalk?

• Both are highly soluble

• Both are insoluble

• Sidewalk chalk is more soluble

• Classroom chalk is more soluble