chapter 3

What is the empirical formula if you have 88.80% copper and 11.20% oxygen? (M_r (Copper) = 63.5 g mol^-1; M_r (Oxygen) = 16.0 g mol^-1)

• Cu₃O₈

• CuO₄

• Cu₂O

• Cu₄O₁₀

How many grams are in 3.3 mol of Potassium Sulfide? (atomic mass: K = 39.1 g mol^-1; S = 32.1 g mol^-1)

• 364 g

• 454 g

• 238 g

• 132 g

What is the definition for Avogadro's number?

• number of grams per one mole of a substance
• whole number ratio that is a multiple of a chemical formula
• simplest, whole number ratio of a chemical formula
• 6.02 x 10^23 particles per one mole of a substance

What are the units for molar mass?

• g

• amu

• g mol^-1

• L

How many moles are in 3.01 x 10²² atoms of magnesium?

• 0.05 moles

• 1.81 x 10⁴⁶ moles

• 5.00 x 10²¹ moles

• 5 moles

How many grams are in 1.2 x 10²⁴ molecules of CO? (molar mass of CO = 28 g/mol)

• 28.2 g

• 55.8 g

• 6.02 g

• 1.2 g

How many atoms of carbon are in 6.00 g of carbon?

• 1.20x10²⁴ atoms C

• 6.02x10²³ atoms C

• 3.01x10²³ atoms C

• 1.50x10²³ atoms C

How many molecules of sugar (C₆H₁₂O₆) are in a mole?

• 24 molecules
• 180 molecules
• 180 g
• 6.02 x 10²³ molecules

Which compound has the empirical formula of CH₂O?

• HCOOH

• CH₃COOH

• CH₃COOCH₃

• HCOOC₂H₅

How many molecules are there in 150 cm³ of carbon dioxide, CO₂ at room condition?

[Avogadro constant, N_A = 6.02x10²³

mol^-1; Molar volume of gas is 24 dm³ mol-1 at room conditions]

• 3.76x10²¹

• 3.76x10²⁴

• 9.63x10²²

• 9.63x10²¹