Final Exam Review

Balancing Equations

100

Balance this equation: 

_NaI + __F₂ -> 2NaF + I₂

_2_NaI +__F₂ -> 2 NaF + I₂

200

CH4+O2→CO2+H2O

Answer: 

CH4+ 2O2→CO2+2H2O

300

Al+HCl→AlCl3+H2

2Al + 6HCl -> 2AlCl₃ + H₂ 

400

Al2(SO4)3+Ca(OH)2→Al(OH)3+CaSO4

Al₂(SO₄)₃+3Ca(OH)₂→2Al(OH)₃+3CaSO₄

500

__C2H4O2 + __O2 -> __CO2 + __H2O

2 - C - 2 

4 - H - 4 

6 - O - 6

Moles & Molecules

100

 How many molecules of carbon dioxide (CO2) are in 2.50 moles of CO2?

2.50 mol x 6.022 molecules/mol 1.51 x 10^24 molecules of CO2

200

What is the value of Avogadro's number? 

6.02 x 10^23

300

How many atoms are in 2.5 moles of pure Zinc (Zn)?

Answer: 1.5055 x 10^24 

400

How many moles are there in 86.1 grams of NaCl?

Moles (n)=Mass (m)Molar Mass (M)

n=86.1g58.44g/mol≈

1.437 moles

500

Liquid Mercury (Hg) has a density of. If you have a small vial containing 5.0 mL of mercury, how many moles of Mercury are in the vial?

Answer: 0.337 moles

Defintions

100

 A double covalent bond shares ___________ electrons between atoms

What is the number four

200

When converting between moles and atoms, what value is important for your conversion? Looking for a specific number!

What is Avogadro's number

300

What is a double replacement reaction?

a. the reactants are usually a metal and nonmetal
b. one of the reactants is often water
c. the reactants are generally two ionic compounds in aqueous solutions
d. energy in the form of heat or light is often produced

c. The reactants are generally two ionic compounds in aqueous solutions

400

Question: Balance H2 + O2 -> H2O 

2H2 + O2 

500

In a double replacement reaction,

a. the reactants are usually a metal and nonmetal
b. one of the reactants is often water
c. the reactants are generally two ionic compounds in aqueous solutions
d. energy in the form of heat or light is often produced

C. the reactants are generally two ionic compounds in aqueous solution

Empirical Formulas

100

A compound contains 4 g of hydrogen and 32 g of oxygen.
What is the empirical formula of the compound?

Given: 4 g H and 32 g O

• Convert to moles:
  H: 41=414=4 mol
  O: 3216=21632=2 mol
• Simplify ratio (divide by 2):
  H : O = 2 : 1
• 
  
• Empirical Formula: H₂O

200

A compound is 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.
What is the empirical formula?

Assume 100 g sample:
C = 40.0 g, H = 6.7 g, O = 53.3 g

• Convert to moles:
  C: 40.012≈3.331240.0≈3.33
  H: 6.71=6.716.7=6.7
  O: 53.316≈3.331653.3≈3.33
• Divide by smallest (3.33):
  C: 1, H: 2, O: 1

✅ Empirical Formula: CH₂O

300

Empirical formula: CH₂O

• Empirical molar mass:
  12+2(1)+16=3012+2(1)+16=30 g/mol
• Given molar mass = 180 g/mol
  18030=630180=6
• Multiply subscripts by 6:

✅ Molecular Formula: C₆H₁₂O₆

400

Unknown Compound

Given: 10.0 g Ca, 6.0 g C, 24.0 g O

• Convert to moles:
  Ca: 10.040=0.254010.0=0.25
  C: 6.012=0.50126.0=0.50
  O: 24.016=1.501624.0=1.50
• Divide by smallest (0.25):
  Ca: 1, C: 2, O: 6

✅ Empirical Formula: CaC₂O₆

500

Given: 16.5 g CO₂ and 9.0 g H₂O. Find the Empirical Formula 

Step 1: Find moles of C and H

• CO₂ → C:
  16.544=0.3754416.5=0.375 mol C
• H₂O → H:
  9.018=0.50189.0=0.50 mol H₂O
  0.50×2=1.000.50×2=1.00 mol H

Step 2: Ratio
C : H = 0.375 : 1.00

Divide by smallest (0.375):
C: 1, H: ≈ 2.67

Multiply by 3:
C: 3, H: 8

✅ Empirical Formula: C₃H₈

Formula Equations?

100

Given: 4 grams of H and 32 g of O. Convert these into moles. 

What is the Empirical Formula that is H: 4 mol & O: 2 mol. 

200

A compound is 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.

What is the empirical formula?

300

A compound has an empirical formula of CH₂O and a molar mass of 180 g/mol.

What is the molecular formula?

400

A compound contains 10.0 g of calcium, 6.0 g of carbon, and 24.0 g of oxygen.

Determine the empirical formula

500

A hydrocarbon is burned, yielding 16.5 g of CO2 and 9.0 g of H2O. Which of the following is the empirical formula of the compound. 

A) CH2 

B) C2H2 

C) C3H8 

D) C4H10 

C) C3H8