Semester One Review

Ionic Compounds

100

What is the charge of magnesium in MgCr₂O₇?

2+

200

What is the charge on the Fe in FeO₂?

4+

300

What is the formula for the compound aluminum(III) phosphide?

AlP

400

What is the charge of permanganate (MnO₄)?

Example: Silver(III) permanganate is Ag₂(MnO₄)₃

2-

500

What is the charge on Sn in Sn₂S₃?

3+

Stoichiometry

100

What is the molar ratio between N₂ and O₂ in the following reaction:

3(NH₄)₂Cr₂O₇ → 2N₂ + 9H₂O + 3Cr₂O₃ + 2NH₃ + 32O₂

2 mol : 32 mol

(also 1 mol : 16 mol)

200

What is the concentration in mM made by dissolving 20.0 mg nitric acid (HNO₃) in 500.0 mL of water?

6.36 mM

300

What is the limiting reactant when 23.0 mol Cl₂ reacts with 40.0 mol Na?

2Na(s)+Cl₂(g)→2NaCl(s)

Na

400

Consider the following reaction:

4HNO₃ → 2H₂O + 4NO₂ + O₂ 

How many molecules of O₂ are synthesized when 10.00 mol HNO₃ decomposes via this reaction?

1.506 x 10²⁴ molecules

500

How many g of NO₂⁺ is synthesized when 10.0 g HNO₃ decomposes via the following reaction:

63.0 g/mol  46.0 g/mol  62.0 g/mol   18.1 g/mol

__HNO₃ <-> __NO₂⁺ + __NO₃^- + __H₂O

3.65 g

Acids and Bases

100

What are the products in the following Bronsted-Lowry acid base reaction?

HNO₃ + HONH₂ <-> 

HNO₃ + HONH₂ <-> NO₃^- + HONH₃⁺

200

What is the K_b of HAsO₄^2-.

1.0 x 10^-7

(Same as K_a2 AND [OH^-] and [H⁺] of neutral water!

300

Which of these is the strongest acid:

HSO₄^-

H₃PO₄

C₆H₅NH₃⁺

HSO₄^- - 1.2 x 10^-2

H₃PO₄ - 7.5 x 10^-3

C₆H₅NH₃⁺ - 2.33 x 10^-5

400

What is the pH of a solution made from 10.15 M Boric acid?

x²/10.15 = 5.8 x 10^-10

x² = 5.887 x 10^-9

x = 7.67 x 10^-5

pH = 4.12

500

What is the pH made from a buffer solution of 0.34 M ammonia (NH₃) and 0.78 M ammonium (NH₄⁺)?

pKa = -log(1.0x10^-14/1.8x10^-5) = 9.255

pH = 9.255 + log(0.34/0.78)

pH = 8.89

Equilibrium

100

What does "dynamic equilibrium" mean? What does "static equilibrium" mean? Demonstrate this definition using the population of a city as an example.

Dynamic equilibrium - population doesn't change because move in and out at the same rate

Static equilibrium - population doesn't change because no one moves in or out at all

200

What is the equilibrium constant expression for the following reaction:

3Na₂MnO₄(aq) + 2H₂O(l) → 2NaMnO₄(aq) + MnO₂(aq) + 4NaOH(aq)

K_C = (NaMnO₄)²(MnO₂)(NaOH)⁴/(Na₂MnO₄)³

300

Considering the following reaction:

3Na₂MnO₄(aq) + 2H₂O(l) → 2NaMnO₄(aq) + MnO₂(aq) + 4NaOH(aq)

 
How will the equilibrium shift in the following instances:

Water is added

MnO₂ is added

NaOH is removed

Water added - Nothing! It's a liquid

MnO₂ added - left

NaOH removed - right

400

Considering the following reaction:

2NH₄MnO₄(s) → 2MnO₂(aq) + N₂(aq) + 4H₂O(l)

What is the equilibrium constant if, at equilibrium, the following values are measured:

25.0 g NH₄MnO₄

0.500 M MnO₂

0.750 M N₂

15.0 mL H₂0

0.188

500

Consider the following reaction:

PH₃BCl₃(g) <-> PH₃(g) + BCl₃(g)            Kc = 0.150

Supposing we allow 3.00 M PH₃BCl₃ to come to equilibrium, what will be the final concentration of each substance?0.6

0.600 M = [PH₃] = [BCl₃]

2.40 M = [PH₃BCl₃]