moles to volume & % Composition

Multiple Choice

How many moles is 12.5 x 10²³ atoms of an unknown compound?

• 2.08mol

• 6.02x10²³mol

• 2.08x10²³mol

• 12.5mol

Mole- Particle (atoms)

1 mole = Avogadro's number

Avogadro's number= 6.02 x 10²³ atoms

Mole- Mass Conversions

1 mole = Molar mass of the element or Compound

Molar mass: Atomic mass given in grams

Multiple Choice

How many moles is 17g of water?

• 0.94mol

• 1.05mol

• 17mol

• 18.015mol

Mole- Volume

Volume Standard: 22.4L

1 mole= 22.4L

Normally only used for liquids

Multiple Choice

Which conversion factor would be used to convert liters to moles?

• Moles/Liters

• Liters/Moles

• grams/liters

• liters/grams

Multiple Choice

How many L are in 5.6 moles of N2 gas?

• 125.44

• 22.4

• 0.25

• 5.6

Multiple Choice

How many moles are in a 18 L tank of nitrogen gas?

• 0.9 moles

• 1 mole

• 0.8 moles

• 0.75 moles

Double Step (or MultiStep) Mole Conversions

• Can be broken down into multiple single steps

• You can do multiple steps using one substance A and go from grams to mole to L or L to moles to particles or you can do multiple steps using two substances.

• For multiple steps, use the steps below: Step 1: Get to moles of A from wherever you are

• Step 2: Use mole ratio to go from moles of A to moles of B

• Step 3: Go from moles of B to the answer of the question by using the proper process to go to grams, liters, or particles of B (depending on what the question asks)

Multiple Choice

How many molecules are in 64 g of O₂?

• 2

• 1.204 x 10²⁴

• 3.01 x 10²³

• 6.02 x 10²³

Multiple Choice

How many molecules are in 11.2 L of O₂ at STP?

• 0.5

• 2

• 3.01 x 10²³

• 6.02 x 10²³

Multiple Choice

What is the mass in grams of $$5.12\ x\ 10^{21}$$  atoms of Al?

• 0.229 grams

• 1.17 grams

• 31.7 grams

• 55.85x10²³ grams

Multiple Choice

What is the percentage of Copper in Cu₂S?

• 79.8%

• 40%

• .798

• .4

Example 1 in detail

Example 2 in detail

Percent Composition Formula

Multiple Choice

What is the percent by mass of sodium in NaCl?

• 39%

• 61%

• 35%

• 65%

Multiple Choice

What is the percent by mass of N in (NH₄)₂S?

• 47.1%

• 68.1%

• 44.1%

• 41.1%