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?