Mole Concept

What is the molar mass of water (H2O)?

• 16.00 g/mol

• 20.18 g/mol

• 22.99 g/mol

• 18.02 g/mol

Answer explanation

The molar mass of water (H2O) is calculated by adding the molar masses of its constituent elements: 2 hydrogen (1.01 g/mol each) and 1 oxygen (16.00 g/mol). Thus, (2 x 1.01) + 16.00 = 18.02 g/mol, making 18.02 g/mol the correct answer.

Calculate the number of moles in 50 grams of NaCl.

• 0.75 moles

• 0.8547 moles

• 1.2 moles

• 0.5 moles

In the reaction 2H2 + O2 -> 2H2O, how many moles of H2 are needed to produce 4 moles of H2O?

• 6 moles of H2

• 2 moles of H2

• 8 moles of H2

• 4 moles of H2

What is the empirical formula of C6H12O6?

• C2H4O2

• C6H12O6

• CH2O

• C3H6O3

If 3 moles of A react with 2 moles of B, how many moles of C can be produced in the reaction A + B -> C?

• 1 mole of C

• 4 moles of C

• 3 moles of C

• 2 moles of C

Determine the molar mass of carbon dioxide (CO2).

• 22.02 g/mol

• 36.46 g/mol

• 44.01 g/mol

• 28.01 g/mol

What is the molecular formula of a compound with an empirical formula of CH2 and a molar mass of 84 g/mol?

• C7H14

• C5H10

• C6H12

• C4H8

In the reaction 4Fe + 3O2 -> 2Fe2O3, how many grams of Fe2O3 are produced from 8 moles of Fe?

• 500 grams

• 1000 grams

• 250 grams

• 638.76 grams

If a compound has a molar mass of 78 g/mol and contains 6 carbons, what is its empirical formula?

• CH

• C2H2

• C3H4

• C6H12

How many moles are in 250 mL of a 0.5 M NaOH solution?

• 0.5 moles

• 0.25 moles

• 0.75 moles

• 0.125 moles