Unit 3 Exam Review

Mass

Moles

Molecular Formula

Percent Composition

Mole ratios

100

The formula mass of Fe₃(PO₄)_{2 is}

357.4 g

100

How many moles are in 2.3 grams of phosphorus?

0.074 moles

100

What is the molecular formula of CH₂O is the molecular mass equals 180 g?

C₆H₁₂O₆

100

What is the percent composition for nitrogen in Ca(NO₃)₂?

17.1% N

100

N2 + 3 H2 → 2 NH3

What is the mole ratio between hydrogen gas and ammonia?

3:2

200

The molar mass of nitrogen is

28 g

200

How many moles are in 98 g of CO₂?

2.27 moles

200

The empirical formula of a compound is CH₂F and the formula mass is 66.0 g, what is the molecular formula?

C₂H₄F₂

200

What is the percent composition of oxygen in Fe₂O₃?

30.1% O

200

If 3.00 moles of H2O are produced, how many moles of oxygen must be consumed?

2 H2 + O2 → 2 H2O

1.5 moles of O

300

How many grams are in 0.02 moles of beryllium iodide, BeI₂?

5 grams

300

How many moles are in 25 grams of water?

1.39 moles

300

What is the molecular formula of the compound Na₂S₂O₃if the molecular mass equals 496 grams?

Na₄S₄O₆

300

Calculate the percentage of nitrogen in urea, CO(NH₂)₂

46.6% N

300

If 2.5 moles of H2O are produced, how many moles of hydrogen gas must be used?

2 H2 + O2 → 2 H2O

2.5 moles

400

What is the gram formula mass for lithium carbonate?

73.89 g

400

How many moles are there in 300 grams of sodium bicarbonate?

3.57 moles

400

How many atoms/particles are in 12 grams of C?

6.022 x 10²³ atoms of carbon

400

What is the percentage of oxygen in carbon dioxide?

72.7% O

400

How many moles of H2O are produced when 5 moles of oxygen are used?

2 H2 + O2 → 2 H2O

10 moles

500

How many grams are in 10.5 moles of fluorine gas?

200 g

500

How many moles are in 1.2 x 10³ grams of NH₃?

71 moles

500

How many oxygen atoms are in 10 molecules of Al₂(SO₄)₃?

120 atoms of oxygen

500

A newly synthesized compound is known to contain the elements zinc and oxygen. When a 20.00 g sample is decomposed, 16.07 g of zinc remains. What is the percent composition of both oxygen and zinc in this compound?

80.35% Zn

19.65% O

500

Suppose 4.0 grams of H2 were used? How many grams of water would be produced?

2 H2 + O2 → 2 H2O

36 grams