IIT/JEE Chemistry Practice #2: Molar Mass/Stoichiometry

Dave explains two practice problems involving molar mass and stoichiometry. The first problem requires converting molecules of copper sulfate pentahydrate to moles using Avogadro's number and then calculating the mass. The second problem involves determining how many grams of oxygen will react with aluminum by forming and balancing a chemical equation, then using stoichiometric ratios to find the answer.

What is the main focus of the practice problem introduced by Dave?

• Calculating the speed of a car

• Understanding molar mass and stoichiometry

• Learning about photosynthesis

• Exploring the history of chemistry

How do you convert molecules to moles in the first question?

• Using a calculator

• Using Avogadro's number

• Using a ruler

• Using the periodic table

What is the molar mass of copper sulfate pentahydrate calculated in the first question?

• 150.25 grams per mole

• 249.68 grams per mole

• 100.12 grams per mole

• 200.50 grams per mole

What compound is formed when aluminum reacts with oxygen?

• Aluminum nitrate

• Aluminum chloride

• Aluminum oxide

• Aluminum sulfate

What is the balanced chemical equation for the reaction between aluminum and oxygen?

• Al + O2 -> AlO

• 3Al + 2O2 -> Al2O3

• 4Al + 3O2 -> 2Al2O3

• 2Al + 3O2 -> 2Al2O3

What is the stoichiometric ratio of aluminum to oxygen in the reaction?

• 2:3

• 1:1

• 3:2

• 4:3

How many grams of oxygen react with 27 grams of aluminum?

• 18 grams

• 24 grams

• 36 grams

• 30 grams