Percent Composition and Hydrates in Chemistry

This video tutorial by Miss Fornell covers the concept of percent composition in chemistry. It explains how to calculate the percent composition of compounds using examples like magnesium chloride and aluminum sulfate. The tutorial also demonstrates how to find the grams of an element in a compound and introduces dimensional analysis and hydrates. The video emphasizes the importance of showing all work and using significant digits.

What is the basic formula for calculating percent composition in chemistry?

• Whole minus part, multiplied by 100

• Part plus whole, divided by 100

• Whole divided by part, multiplied by 100

• Part divided by whole, multiplied by 100

In the example of magnesium chloride, what is the molar mass of chlorine used in the calculation?

• 24.3

• 35.45

• 70.9

• 95.2

How many chlorine atoms are present in the chemical formula of magnesium chloride?

• Three

• Four

• Two

• One

What is the percent composition of aluminum in aluminum sulfate?

• 25.53%

• 15.77%

• 74.47%

• 81.10%

How do you calculate the mass of aluminum in a 250g sample of aluminum sulfate?

• Add 0.1577 to the total mass

• Divide the total mass by 0.1577

• Multiply the total mass by 0.1577

• Subtract 0.1577 from the total mass

What is the percent composition of calcium in calcium nitrate?

• 81.10%

• 51.17%

• 48.83%

• 37.0%

In dimensional analysis, what is the mole ratio of calcium to calcium nitride?

• 1:1

• 1:2

• 3:1

• 1:3

What is a hydrate in chemistry?

• A salt with water molecules attached

• A salt with extra electrons

• A compound with extra hydrogen

• A compound with extra oxygen

How many water molecules are attached to magnesium sulfate in its heptahydrate form?

• Five

• Six

• Seven

• Eight

What is the percent of water in magnesium sulfate heptahydrate?

• 37.0%

• 51.17%

• 48.83%

• 25.53%