Moles & Molarity Review

Molarity

100

What is the molarity of a sodium hydroxide solution with 0.090 moles dissolved to make 0.80 liters of solution.

0.11 M NaOH

200

What is the molarity of a sodium chloride solution containing 6.75 grams of solute in a total of volume of 0.452 L of solution?

0.256M NaCl

300

If 25.0 ml of a 6.00M HCl solution is diluted to 125 ml, what is the new concentration?

1.20M HCl

V₁M₁  = V₂M₂

(25.0ml)(6.00M) = (125ml)(X)

400

What volume (in milliliters) of a 0.966 M solution contains 0.0245 moles of solute?

25.4 mL

500

How many grams of sodium chloride are needed to make 230.0 mL of a 0.26M NaCl solution?

3.5 grams NaCl

Moles

100

What is the molar mass of sodium?

22.99 g/mol

200

What is the molar mass of sodium carbonate?

105.99 g/mol

Na₂CO₃

22.99+22.99+12.01+16.00+16.00+16.00=105.99 g/mol

300

How many atoms are contained in  0.11 moles of carbon?

6.6 x 10²² carbon atoms

moles x Avogadro's number 

= 0.11 x 6.02x10²³ 

= 6.6 x 10²² atoms

400

What is the mass of 3.62 moles of hydrogen gas?

7.31 grams H₂

Hydrogen is diatomic: H₂

moles x mole mass = 3.62 x 2.02 = 7.31 grams

500

What is the mass of 3.03 moles of ammonium carbonate?

291. grams (NH₄)₂CO₃

moles x molar mass = 3.03 x 96.11 = 291 grams

(NH₄)₂CO₃ =   (2x14.01) + (8x1.01) + 12.01 + (3x16.00) = 96.11 g/mol

Nomenclature

100

What is the formula of dinitrogen trioxide?

N₂O₃

200

What is the name of P₄O₁₀?

tetraphosphorus decoxide

300

What is the name of Al₂O₃?

aluminum oxide

400

What is the formula for ammonium phosphite?

(NH₄)₃PO₃

500

What is the name of Sn(C₂H₃O₂)₄?

tin(IV) acetate

Atoms/Grams to...

100

How many moles are in 3.03 grams of silver?

0.0281 moles

mass/mole mass = 3.03/107.87 = 0.0281 moles

200

How many moles are contained in 8.20x10³² atoms of uranium?

1.36x10⁹ moles U

atoms/Avogadro's number

8.20x10³²/6.02x10²³ = 1.36x10⁹ moles (1,400,000,000 moles)

300

How many atoms are contained in 0.0321 grams of gold?

9.81x10¹⁹ atoms

grams/mole mass = moles

0.0321/196.97 = 1.62969x10^-4 moles

moles x Avogadro's number = atoms

1.6337x10^-4 x 6.022x10²³ = 9.839x10¹⁹ atoms

Au = 196.97 g/mole

400

What is the mass of 2.99x10²³ formula units of sodium chloride?

29.0 grams

formula units/Avogadro's number = moles

2.99x10²³/6.022x10²³ = 0.497 moles

moles x mole mass = grams

0.497 x 58.44 = 29.0 grams

NaCl = 22.99+35.45=58.44 g/mole

500

How many molecules are found in 32.0 grams of dihydrogen monoxide?

1.07x10²⁴ atoms

grams/mole mass = moles

32.0/18.02 = 1.8 moles

moles x Avogadro's number = atoms

1.7758 x 6.02x10²³ = 1.07x10²⁴ atoms

H₂O = 1.01+1.01+16.00=18.02 g/mole

Gases

100

What is the molar volume of any gas at STP?

22.4 liters

200

What is the volume of 7.50 moles of nitrogen gas at STP?

168 liters

300

How many moles are in 888 mL of hydrogen gas at STP?

0.0396 moles

400

What is the mass of 81.5 liters of carbon dioxide at STP?

160. grams

500

How many molecules are in 531 ml of sulfur trioxide gas at STP?

1.43x10²² molecules SO₃