Assessment Quiz: Lesson 1: Chemical Reaction Rates and Le Chatelier's Principle

Question 1

For the exothermic Haber-Bosch reaction N2(g) + 3 H2(g) ⇌ 2 NH3(g) (ΔH = -92 kJ), which change increases the equilibrium constant Kc?

Accepted Answer

Lowering the temperature of the system

Answer

Increasing the total pressure

Answer

Adding an iron catalyst

Answer

Increasing the concentration of nitrogen gas

Question 2

What is the exact chemical deduction according to Egyptian curriculum standards for: Electronic Configuration of the First Transition Series?

Accepted Answer

Chromium (Cr: 24) has an anomalous configuration [Ar] 4s1 3d5 to achieve half-filled d-subshell stability, and Copper (Cu: 29) is [Ar] 4s1 3d10 for completely filled d-subshell stability

Answer

Both Chromium and Copper have fully filled 4s2 orbitals

Answer

Scandium (Sc: 21) exhibits stable oxidation states of +1, +2, and +3

Answer

Zinc (Zn: 30) is considered a typical transition element in all its compounds

Question 3

What is the exact chemical deduction according to Egyptian curriculum standards for: Le Chatelier's Principle in Gas-Phase Equilibrium?

Accepted Answer

Increasing pressure on an equilibrium mixture shifts the reaction toward the side with fewer moles of gas, without changing the equilibrium constant (Kc)

Answer

Increasing temperature always increases the value of Kc for exothermic reactions

Answer

Adding a catalyst shifts the equilibrium position toward products

Answer

Decreasing volume increases the value of Kp for any reaction

Question 4

What is the exact chemical deduction according to Egyptian curriculum standards for: Standard Hydrogen Electrode (SHE) and Galvanic Cells?

Accepted Answer

SHE has an arbitrarily defined standard potential E° = 0.00 V under standard conditions (1 atm H2 gas, 1.0 M H+ solution, 298 K)

Answer

SHE potential changes to 1.00 V when connected to Zinc

Answer

The standard hydrogen electrode uses pure copper wire without platinum black

Answer

SHE can only act as an anode and never as a cathode

Question 5

What is the exact chemical deduction according to Egyptian curriculum standards for: Markovnikov's Rule in Electrophilic Addition to Alkenes?

Accepted Answer

When an asymmetric reagent (HX) adds to an asymmetric alkene, the positive hydrogen ion attaches to the double-bonded carbon with more hydrogen atoms, while the halide adds to the more substituted carbon

Answer

Hydrogen always attaches to the carbon with fewer hydrogen atoms

Answer

Markovnikov's rule applies exclusively to symmetrical alkynes like ethyne

Answer

Addition occurs with the halogen attaching to the terminal methyl group

Question 6

STEM Chemistry Problem 1: A 25.0 mL sample of 0.10 M H2SO4 is completely neutralized by 0.20 M NaOH. What volume of NaOH solution is required to reach the equivalence point?

Accepted Answer

25.0 mL of NaOH

Answer

50.0 mL of NaOH

Answer

12.5 mL of NaOH

Answer

10.0 mL of NaOH

Question 7

STEM Electrochemistry Problem 1: In a Daniell cell, Zn | Zn2+ (1 M) || Cu2+ (1 M) | Cu, given E°(Zn2+/Zn) = -0.76 V and E°(Cu2+/Cu) = +0.34 V, what is the standard electromotive force (E°cell)?

Accepted Answer

+1.10 V (spontaneous galvanic cell)

Answer

+0.42 V

Answer

-1.10 V (electrolytic cell)

Answer

+0.58 V

Question 8

STEM Faradaic Problem 1: What mass of copper (atomic mass = 63.5 g/mol) is deposited at the cathode when a constant current of 9.65 A passes through a CuSO4 solution for 1,000 seconds? (Faraday constant = 96,500 C/mol)

Accepted Answer

3.175 g of Cu

Answer

6.35 g of Cu

Answer

1.587 g of Cu

Answer

12.70 g of Cu

Question 9

STEM Organic Chemistry Problem 1: Catalytic hydration of acetylene (ethyne, C2H2) with H2O in the presence of 40% H2SO4 and 1% HgSO4 at 60°C yields which intermediate and final product?

Accepted Answer

Unstable vinyl alcohol intermediate that tautomerizes to Acetaldehyde (Ethanal, CH3CHO)

Answer

Ethyl alcohol (Ethanol) directly in one step

Answer

Acetic acid (Ethanoic acid) directly

Answer

Ethylene glycol through addition

Question 10

STEM Chemical Equilibrium Problem 1: For the equilibrium reaction: N2(g) + 3 H2(g) <=> 2 NH3(g) (ΔH = -92 kJ/mol), which change will shift the equilibrium to the right and increase ammonia yield?

Accepted Answer

Decreasing temperature and increasing total pressure

Answer

Increasing temperature and decreasing pressure

Answer

Adding a positive catalyst at constant volume

Answer

Removing nitrogen gas continuously from the chamber

Comparative Analysis: Effect of External Stresses on Reversible System: N2(g) + 3 H2(g) ⇌ 2 NH3(g) (ΔH = -92 kJ)

03 3. Comparative Analysis: Effect of External Stresses on Reversible System: N2(g) + 3 H2(g) ⇌ 2 NH3(g) (ΔH = -92 kJ)

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