Calcutta University BSc II (Chemistry)

Unit II. Basic physical chemistry VI

Practice Questions:

1.       Define the term oxidation and reduction.

2.       A positron has a mass number of _____, a charge of _____, and a mass equal to that of a(an) _____.

3.       The lead-containing reactant(s) consumed during recharging of a lead-acid battery is/are __________.

4.       How many grams of CuS are obtained by passing a current of 12 A through a solution of CuSO4

for 15 minutes __________ ?

5.       Why every combustion reaction is an oxidation-reduction reaction?

6.       What is the function of the electrolyte in a galvanic cell?

7.       Molten AlCl₃ is electrolyzed for 5.0 hours with a current of 0.40 amperes. Metallic aluminum is produced at one electrode and chlorine gas, Cl₂, is produced at the other. How many liters of Cl₂ measured at STP are produced when the electrode efficiency is only 65%?

8.       What is the value of E for the half-cell:
MnO₄^- (0.010 M) + 8H⁺ (0.20 M) + 5e^-  Mn²⁺ (0.020 M) + 4H₂O?

9.       What is the oxidation number of potassium in KMnO₄?

10.   What is the difference between a storage battery and a fuel cell?

11.   What is a PEM fuel cell?

12.   What reaction prevents us from using Zn as an electrode of the first kind in acidic solutions? Which other electrodes of the first kind would you expect to behave in the same manner as Zn when immersed in an acidic solution?

13.   Explain why each of the following decreases the analysis time for controlled-potential coulometry: a larger surface area for the working electrode, a smaller volume of solution, and a faster stirring rate.

14.   Write Nernst equation for Fe⁺³ and Fe⁺².

15.   Write the reactions occurring at the anode and the cathode for the potentiometric electrochemical cell with the following shorthand notation.

Pt(s) |H₂ (g) H⁺ (aq) ||Cu²⁺(aq ) |Cu(s)

Calcutta University (BSc II) Chemistry

CGT 22b

Unit 1. Basic physical chemistry V

Practice questions

1.       What are protic and aprotic solvents?

2.       What is conjugated base of ethanol?

3.       Why in some cases ammonia is preferred over water as a solvent?

4.       What are coordination complexes?

5.       Why oil and water do not mix?

6.       Arrange OCH₃^- , CH₃CH₂^- , NH₂^- and F^- in decreasing order of basicity?

7.       Define Bronsted –Lowry Acids and bases?

8.       Define HSAB?

9.       What is the pH of a 0.1M solution of sodium acetate?

10.   Calculate
the
ratio
of
molarities
of
PO₄^2‐ and
HPO^4‐
ions
in
a
buffer solution
with
a
pH
of
11.0.

11.   Why H‐bonding
is
very
important
in
biological
molecules?

12.   What are conjugated acids and bases?

13.   What compounds are produced when sodium nitrate is added to a mixture of water and ethanol?

14.   Explain why the –OH hydrogen in acetic acid is more acidic than in ethanol.

15.   A 1.0 x 10^-3 M solution of hydrochloric acid is prepared. What is the hydroxyl ion concentration?

16.   Calculate the pOH and the pH of a 5.0 x 10^-2M solution of NaOH.

17.   The basicity constant K, for ammonia is 1.75 x 10^-5 at 25⁰C. Calculate the pH and pOH for a 1.0 x 10^-3 M solution of ammonia.

18.   How many grams ammonium chloride and how many milliliters 3.0 M sodium hydroxide should be added to 200mL water and diluted to 500mL to prepare a buffer of pH 9.5 with a salt concentration of 0.10 M?

19.   Write two examples of Physiological buffers.

20.   Draw all resonance structures of the conjugate base of cyclopentadiene.

21.   Draw all constitutional isomers with molecular formula C₂H₆S, and rank them in terms of increasing acidity.

22.   Explain Henry’s law.

23.   How many grams of solute are needed to prepare 150 mL of a 40.0% (m/v) solution of LiNO3?

24.   How many moles of nitric acid are in 325 mL of 16 M HNO₃ solution?

25.   What volume (L) of 1.5 M HCl solution contains 6.0 moles of HCl?

Experiment

Treading on eggshells

Carefully break off the small end of four eggs and pour out the insides. Wind a piece of sticky tape around the centre of each eggshell. Cut through the centre of the tape to make four dome-shaped shells (discard the broken end of each shell). Lay the four domes on a table with the cut sides down arranged in the shape of a rectangle. How many telephone books you can lay on top of the shells before they break?

The supportive eggshells

Arches — even those made of eggshells — are strong because they exert horizontal as well as vertical forces to resist the pressure of heavy loads. The crown of an eggshell can support heavy books because the weight is distributed evenly along the structure of the egg.

Annihilation meaning

The phenomenon in which a particle and an antiparticle, such as an electron and a positron, meet and are converted completely to energy approximately equivalent to the sum of their masses.

Calcutta University (BSc II) Chemistry

Chemistry General

PART II CGT 22a

Unit II. Basic physical chemistry IV

1.      Are pure solids included in equilibrium expressions? Explain.

2.      What will happen to reaction of system if temperature is raised at equilibrium?

3.      Explain how the equilibrium shifts when energy is added or removed from a system?

4.      What is common ion? Explain how a common ion reduces the solubility of an ionic compound.

5.      How can you use the solubility product constant to calculate the solubility of a sparingly soluble ionic compound?

6.      What is common ion? Explain how a common ion reduces the solubility of an ionic compound.

7.      What is Le Chatelier’s principle? How it is applied to equilibrium systems?

8.      What is the K value for the following equation if the gaseous mixture in a 4 L container reaches equilibrium at 1000 K and contains 4.0 mol of N₂, 6.4 mol of H₂, and 0.40 mol of NH₃?                                       

               N₂(g) + 3H₂(g) ←→ 2NH₃(g)

9.      What is the Tyndall effect? Give a common example of this effect.

10.  What is the difference between a solute and solvent? Name a compound considered to be ‘universal’ solvent?

11.  Given an unknown mixture consisting of two substances, explain how a scientist could use lab techniques to determine whether the mixture is a true solution, a colloid or a suspension.

12.  Which out of milk, blood, fog and mayonnaise is not an example of colloid?

13.   Describe Brownian motion. How it is caused?

14.  Distinguish between colloids and true solutions?

15.  How does a colloid differ from a suspension?

16.  What is the difference between hydration and solvation?