Physical Chemistry Answers

A voltaic cell is constructed based on the following reaction and initial concentrations:

Fe²⁺(0.0050 M) + Ag⁺(2.0 M) ↔ Fe³⁺(0.0050 M) + Ag(s)

Calculate [Fe²⁺] when the cell reaction reaches equilibrium.

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

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?

A concentration cell consists of two half-cells with identical electrodes but different ion concentrations.

Consider the following concentration cell (pictured below).

M(s) | M⁺(satd MX) || M⁺(0.100 M)| M(s)   E_cell = 0.417 V

At the anode, a metal electrode (M) is placed in a saturated aqueous solution containing ions of the same metal (M) and a halogen (X), MX. At the cathode, a second electrode of the same metal (M) is placed in a solution with [M⁺] = 0.100 M.The two half-cells are connected by a salt bridge, and the measured cell voltage is 0.417 V. The cell reaction occurring in this concentration cell is

Reduction: M⁺(0.100 M) + e^- → M(s)

Oxidation: M(s) → M⁺(satd MX) + e^-

From this information, calculate the K_sp of MX. 

. A 100ml water sample on titration with N/50H2SO4required 4.7 ml of acid upto phenolphthalein endpoint. Addition of methyl orange to the same solution required 10.5ml of same acid. Elucidate the type and extent of alkalinity present in water sample.

A sample of potash alum K2SO4.Al2(SO4)3.24H2O contains 20 gram atoms oxygen in the sample, then calculate number of gram atoms of sulphur in the same sample

During titration of water sample with N/10H2SO4using phenolphthalein indicator, zero ml of H2SO4 was used. What is inferred from this?

You have been employed as a quality control chemist in a sugar company. As part of your responsibility, a senior worker in the quality control laboratory asked you to prepare 0.5M NaOH in 250cm*3 flask. However NaOH pellets is out of stock, but, there is 800% solution of NaOH on the laboratory bench. With this challenge, show how you can prepare 0.5M NaOH in 250cm*3 flask from a solution of 800% NaOH.

How much heat in calories and kilocalories, does it take to raise the temperature of 814g of water from 18.0°C to 100.0°C.

Calculate the heat capacity of the sample beake fluid if a temperature rise from 15° to 100° C requires the absorption of 911J of heat.