Chemical Composition and Molar Mass

The video tutorial covers three-step mole problems using sodium phosphate and magnesium sulfate heptahydrate as examples. It begins with calculating the grams of sodium in sodium phosphate, followed by determining the number of sodium atoms using Avogadro's number. The tutorial then shifts to magnesium sulfate heptahydrate, where the focus is on calculating the number of oxygen atoms. The video emphasizes understanding molar mass, percentage composition, and the application of Avogadro's number in solving chemistry problems.

What is the correct chemical formula for sodium phosphate?

• Na3PO4

• Na2PO4

• Na4PO3

• NaPO4

How many grams of sodium are present in 29.5 grams of sodium phosphate?

• 12.41 grams

• 20.00 grams

• 10.00 grams

• 15.00 grams

What is the molar mass of sodium phosphate?

• 164 grams per mole

• 180 grams per mole

• 200 grams per mole

• 150 grams per mole

How many sodium atoms are in 29.5 grams of sodium phosphate?

• 4.00 x 10^23

• 2.00 x 10^23

• 3.25 x 10^23

• 1.08 x 10^23

What is the chemical formula for magnesium sulfate heptahydrate?

• MgSO4.5H2O

• MgSO4.7H2O

• MgSO4.8H2O

• MgSO4.6H2O

What is the molar mass of magnesium sulfate heptahydrate?

• 246 grams per mole

• 150 grams per mole

• 200 grams per mole

• 300 grams per mole

How many moles of magnesium sulfate heptahydrate are in 71.5 grams?

• 0.20 moles

• 0.40 moles

• 0.50 moles

• 0.29 moles

How many oxygen atoms are present in magnesium sulfate heptahydrate?

• 9 oxygen atoms

• 10 oxygen atoms

• 11 oxygen atoms

• 12 oxygen atoms

How many total compounds of magnesium sulfate heptahydrate are in 71.5 grams?

• 1.50 x 10^23

• 2.00 x 10^23

• 2.50 x 10^23

• 1.75 x 10^23

What is the total number of oxygen atoms in 71.5 grams of magnesium sulfate heptahydrate?

• 2.00 x 10^24

• 1.50 x 10^24

• 1.92 x 10^24

• 2.50 x 10^24