Question

1) How many moles of water, H2O, contain 2.0×10²² molecules of water?

Express the quantity in moles to two significant figures.

Moles of water =

___________

mol

2) In the gaseous state, chlorine exists as a diatomic molecule Cl2 (Molar mass = 70.9 g/mol). Calculate the number of moles of chlorine present in 140  g of chlorine gas.

Express the quantity in moles to three significant figures.

Moles of chlorine gas =

___________

mol

3)

Sodium hydroxide, NaOH, is a strong base that is used in industrial synthesis and processes such as making paper.

What is the mass of 2.10 ×10²² molecules of NaOH (Molar mass = 40.0 g/mol)?

Express the mass in grams to three significant figures.

Mass of NaOH =

___________

g

4)

Ascorbic acid, or vitamin C (C6H8O6, molar mass = 176 g/mol), is a naturally occurring organic compound with antioxidant properties. A healthy adult’s daily requirement of vitamin C is 70-90 mg. A sweet lime contains 2.87×10⁻⁴ mol of ascorbic acid.

To determine whether the ascorbic acid in a sweet lime meets the daily requirement, calculate the mass of ascorbic acid in 2.87×10⁻⁴ mol of ascorbic acid.

Express the mass in grams to three significant figures.

Mass of ascorbic acid =

___________

g

  

Answer 1