Percent Composition and Mole Calculation

Find the percent composition of Cu₂S?

• %Cu= 67.987 %S= 32.013

• %Cu= 79.853   %S= 20.147

• %Cu= 35.946   %S= 64.054

How many moles are in 2.2x10²⁴ atoms of argon?

g

h

d

i

6.02x10²³ atoms

1 mole

0.27 moles

6.02x10²³ moles

1.3x10⁴⁸ moles

6.02x10²³ molecules

3.7 moles

2.2x10²⁴ atoms

6.02x10²³ compounds

6.02x10²³ formula units

How many liters will 3.59 moles of N₂ contain?

• 80.42 L N₂

• 67.2 L N₂

• 79 L N₂

• 22.4 L N₂

What is the percent by mass of oxygen in MgO?

• 20%

• 40%

• 50%

• 60%

What is the percent by mass of chlorine in NaCl?

• 39%

• 61%

• 35%

• 65%

What is the percent by mass of fluorine in CaF₂ (gram-formula mass = 78 g/mol)?

• 24%

• 49%

• 51%

• 65%

What is the percent composition by mass of sulfur in the compound MgSO₄ (gram formula mass = 120 g/mol)?

• 20%

• 27%

• 46%

• 53%

In which compound is the percent composition by mass of Cl equal to 42%?

• HClO (gram formula mass = 52 g/mol)

• HClO₂ (gram formula mass = 68 g/mol)

• HClO₃ (gram formula mass = 84 g/mol)

• HClO₄ (gram formula mass = 100 g/mol)

What percentage of the total atomic mass of magnesium bromide (MgBr₂) is composed of bromine? Hint - consider the mass of both atoms of bromine in your calculation.

• 13%

• 43%

• 63%

• 87%

Calculate the percent composition of hydrogen in water (H2O).

• A) 11.19%

• B) 22.22%

• C) 33.33%

• D) 44.44%