!CHEM&161 Final Exam Review!

Atoms, Elements, & Compounds

100

The atomic number is equal to the number of ______.

Protons

200

Write the chemical formula for the compound that forms when calcium and chlorine bond.

CaCl₂

300

Write the name for Sn(SO₄)₂

tin (IV) sulfate

400

What is the charge on the Fe ions in Fe₂O₃

3+

500

How many moles of C₅H₁₂ contain 9.25 × 10²⁴ molecules of C₅H₁₂ ?

15.4 moles

Reactions & Stoichiometry

100

Why do Li, Na, and K have similar chemical properties?

They are in the same group and therefore have the same number of valence electrons (which dictate reactivity)

200

Balance the following reaction:

_____ CH₄O+ _____ O₂ → _____ CO₂ + _____ H₂O

2,3,2,4

300

Write the balanced equation for the fermentation of sucrose (C₁₂H₂₂O₁₁), in which aqueous sucrose reacts with water to produce aqueous ethanol (C₂H₅OH) and CO₂ gas. Be sure to include states!

C₁₂H₂₂O_{11 (aq)}+ H₂O _(l) → 4 C₂H₅OH _(aq) + 4CO_{2 (g)}

400

Magnesium burns in air to produce magnesium oxide:

2 Mg(s) + O₂(g) → 2 MgO(s)

When 5.00 g of magnesium burns, the theoretical yield of magnesium oxide is ________ g.

8.29 g 

500

The density of ethanol, C₂H₅OH, is 0.789 g/mL. How many mL of ethanol are needed to produce 25.0 g of CO₂ according to the following chemical equation?

C₂H₅OH(l) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(l)

16.6 mL

Solutions

100

What two conversion factors can you write from the following molarity? 1.3 M NaOH

1.3 mols NaOH/ 1 L NaOH 

OR

1 L NaOH/ 1.3 mols NaOH

200

Determine the molarity of a solution formed by dissolving 468 mg of MgI₂ in enough water to yield 50.0 mL of solution

0.0337 M

300

Give the complete ionic equation for the reaction that occurs when aqueous solutions of sodium sulfide and iron(II) nitrate are mixed. Clearly label the precipitate (if any).

2 Na⁺_(aq) + S^2-_(aq) + Fe²⁺_(aq) + 2 NO^3-_(aq) → FeS_(s) + 2 Na⁺_(aq) + 2 NO^3-_(aq)

400

What element is undergoing reduction (if any) in the following reaction?

Zn(s) + 2 AgNO₃(aq) → Zn(NO₃)₂(aq) + 2 Ag(s)

Silver (Ag)

500

The titration of 80.0 mL of an unknown concentration H₃PO₄ solution requires 126 mL of 0.218 M KOH solution. What is the concentration of the H₃PO₄ solution (in M)?

(Hint: You'll need to write a balanced equation)

0.114 M

Gases

100

As volume increases, pressure _______.

decreases

200

At STP, 1 mole of any gas occupies 22.4 L. Prove this mathematically, using PV=nRT.

Kayla will write this on the board!

300

What pressure will 14.0 g of CO exert in a 3.5 L container at 75°C?  

4.1 atm

400

Determine the volume of O₂ (at STP) formed when 50.0 g of KClO₃ decomposes according to the following reaction. The molar mass for KClO₃ is 122.55 g/mol.

2 KClO₃(s) → 2 KCl(s) + 3 O₂(g)

13.7 L

500

What pressure would a gas mixture in a 10.0 L tank exert if it were composed of 48.5 g He and 94.6 g CO₂ at 398 K?

46.6 atm

Thermochemistry & Quantum Mechanics

100

Which of the following visible colors of light has the longest wavelength? 

a. blue

b. green

c. yellow

d. red

d. red

200

The sign of ΔH for an endothermic reaction is _____, since endothermic reactions _____ heat. 

a. negative; absorb

b. positive; absorb

c. negative; release

d. positive; release

b. positive; absorb

300

Determine the final temperature of a gold nugget (mass = 376 g) that starts at 45°C and loses 4.85 kJ of heat to a snowbank when it is lost. The specific heat capacity of gold is 0.128 J/g°C.

T_f = -56 °C

400

Use Hess's Law and the enthalpies given below to determine ΔH°rxn for the following reaction:

P₄(g) + 10 Cl₂(g) → 4 PCl₅(s)       ΔHrxn = ?

Given:

PCl₅(s) → PCl₃(g) + Cl₂(g)           ΔH₁ = +157 kJ

P₄(g) + 6 Cl₂(g) → 4 PCl₃(g)       ΔH₂ = -1207 kJ

 ΔH°rxn = -1835 kJ

500

Use the ΔH_f° information provided to calculate ΔH_rxn° for the following:

SO₂Cl₂(g) + 2 H₂O(l) → 2 HCl(g) + H₂SO₄(l) 

ΔH_f° (kJ/mol):

SO₂Cl₂(g) = -364

H₂O(l) = -286

HCl(g) = -92

H₂SO₄(l) = -814

ΔH_rxn° = -62kJ