Physical Chemistry Answers

You are asked to prepare a buffer solution with a pH of 3.50. The following solutions, all 0.100 M, are available to you: HCOOH, CH₃COOH, H₃PO₄ , NaCHOO, NaCH₃COO, and NaH₂PO₄. 

What would be the best combination to make the required buffer solution?

What ratio of [conjugate base]/[acid] would yield the best result for the required buffer solution created in the question above?

T°C

25.2

30.5

40.4

45.0

50.0

P(mmHg)

24.04

32.90

55.50

75.20

102.0

The following data are obtained for vapour pressure temperature of water. Explain the steps to obtain the molar heat of vaporization

A common reference electrode consists of a silver wire coated with AgCl(s) and immersed in 1 M KCl (pictured in Question 7).

AgCl (s) + e^- → Ag(s) + Cl^- (1 M)      E° = 0.2223 V

What is E_cell when this electrode is a cathode in combination with a standard zinc electrode as an anode?

The electrodes in the following electrochemical cell are connected to a voltmeter as shown. The half-cell on the right contains a standard silver-silver chloride electrode (a silver wire coated with AgCl(s), as in questions 5 and 6).  

AgCl (s) + e^- → Ag(s) + Cl^- (1 M)      E° = 0.2223 V

The half-cell on the left contains a silver electrode immersed in 100.0 mL of 1.00 x 10^-3 M AgNO₃(aq). A porous plug through which ions can migrate separates the half-cells. 

What is the voltmeter reading after 10.00 mL of 0.0100 M K₂CrO₄ has been added to the half-cell on the left and the mixture has been thoroughly stirred? 

Hint: K_sp of Ag₂CrO₄ = 1.1 x 10^-12

The electrodes in the following electrochemical cell are connected to a voltmeter as shown. The half-cell on the right contains a standard silver-silver chloride electrode (a silver wire coated with AgCl(s), as in questions 5 and 6).  

AgCl (s) + e^- → Ag(s) + Cl^- (1 M)      E° = 0.2223 V

The half-cell on the left contains a silver electrode immersed in 100.0 mL of 1.00 x 10^-3 M AgNO₃(aq). A porous plug through which ions can migrate separates the half-cells. 

What is the voltmeter reading after 10.00 mL of 0.0100 M K₂CrO₄ has been added to the half-cell on the left and the mixture has been thoroughly stirred? 

Hint: K_sp of Ag₂CrO₄ = 1.1 x 10^-12

What ratio of [conjugate base]/[acid] would yield the best result for the required buffer solution created in NaH₂PO₄ and HCOOH

You are asked to prepare a buffer solution with a pH of 3.50. The following solutions, all 0.100 M, are available to you: HCOOH, CH₃COOH, H₃PO₄ , NaCHOO, NaCH₃COO, and NaH₂PO₄. 

What would be the best combination to make the required buffer solution?

Select one:

a.

NaH₂PO₄ and HCOOH

b.

H₃PO4 and NaH₂PO₄

c.

CH₃COOH and NaCH₃COO

d.

NaH₂PO₄ and NaCHOO  

e.

HCOOH and NaCHOO

Consider the titration of a 25cm3 portion of acid mixture of HX and H2A(1:1 concentration ratio) with 0.1mol dm-3 HCl. Burette readings at the end points with the corresponding indicators are, methyl orange-V1 and phenolphthalein-V2. Which of the following is true regarding the burette readings?

Consider a substance X. It is known that the change in chemical potential of 1 mole

X in its gaseous phase is 10 times of X in liquid phase on isothermal compression

from 1 bar to 10 bar. Assume X behaves ideally in its gaseous state. Determine the

molar volume of X in its liquid phase.

Calculate the change in the entropy of the nitrogen during the transition below. A sample of nitrogen gas is heated from 20 centigrades to 400 centigrades at constant volume. Initial volume and pressure are given as 20liters and 5 kPa.The molar heat capacity of nitrogen at constant volume is 20.81 mole per kelvin per joule.