PAK 6 Concept 1 Review

Multiple Choice

What is Avogadro's number?

• The number of protons in an atom

• The number of particles in one mole of a substance

• The number of electrons in a molecule

• The number of atoms in a crystal lattice

Open Ended

Why is the concept of the mole important in chemistry?

Multiple Choice

Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.

• NaPO₂

• Na₂PO₃

• Na₃PO₄

• NaPO₄

Multiple Choice

Which of the following is the correct molecular formula for a compound with an empirical formula of CH2 and a molar mass of 42 g/mol?

• C2H4

• C3H6

• C4H8

• C6H12

Multiple Choice

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

Multiple Choice

Suppose you find 100 g of an unknown compound that consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

• Mg₄N₃
• MgN₂
• Mg₃N₂ 
• MgN

Multiple Choice

What is the molecular formula for a compound with the empirical formula: K₂SO₄ and a molecular mass of 696g.

• K₂SO₄ 
• K₈SO₁₆
• K₈S₄O₈ 
• K₈S₄O₁₆ 

Multiple Choice

How many moles of carbon are there in 5g of carbon?

• 60 mol
• 17 mol
• 0.42 mol
• 7 mol

Multiple Choice

Find the percent composition of N₂S₂.

• N: 69.6%  S: 30.4%
• N:36% S: 75.6%
• N: 96.6% S: 3.4%
• N: 30.4% S: 69.6%

Multiple Choice

Find the mass in grams of 0.75 moles of magnesium.

• 32 grams
• 18 grams
• 2.21 x 10 ^23 grams

Multiple Choice

Calculate the molar mass of Ba(C₂H₃O₂)₂

• 255.3 g/mol

• 237.3 g/mol

• 228.3 g/mol

• 196.3 g/mol

Multiple Choice

Abigail, Aria, and Isla are working on a chemistry project. They have found an unknown compound with an Empirical Formula of CF₂. They also determined that the Molecular formula mass of the compound is 192 g/mol. Can you help them figure out the Molecular Formula of the compound?

• C₄F₈

• C₈F₄

• C₃F₆

• C₂F₄

Multiple Choice

What is the molecular formula for a compound that contain 36.84g N and 63.16g O?

• N₂O₂

• NO₂

• NO

• N₂O₃

Multiple Choice

What is the molar mass of NaOH?

• 40 g/mol
• 38.989 g/mol
• 23.998 g/mol
• 57.004 g/mol

Multiple Choice

How many molecules are in 2.5 mol of NaCl?

• 1.51x10²³
• 146
• 4.15
• 1.51x10²⁴

Multiple Choice

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

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

Multiple Choice

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

• 1.20x10²⁴atoms C
• 6.02x10²³atoms C
• 3.01x10²³atoms C
• 1.50x10²³atoms C

Multiple Choice

What is the mass of 0.89 mol of CaCl₂?

• 111 grams
• 0.008 grams
• 98.9 grams
• none of the choices

Multiple Choice

Which conversion factor should be used for the following question " How many molecules are there in 4.00 moles of glucose, C₆H₁₂O₆? 

• 1 mole = 78.12 g
• 1 mole = 22.4 L 
• 1 mol = 6.02x 10²³ particles 
• more than one

Multiple Choice

What is the volume of 2 moles of gas at STP?

• 22.4 L
• 44.8 L
• 11.2 L
• 2 L