Physical Chemistry Answers

A student has carried out a moving boundary experiment using K₂SO₄ as an electrolyte.

The data obtained was tabulated in the following Table.

Cation velocity 11.43 mms-1

Cross sectional area of tube 28.56 mm²

Transference number of cation 0.593

Anion concentration 0.025 mol dm^-3

Calculate the current flow for the boundary moves as far as 45 mm.

 An electron in the ground state of a silicon atom has the quantum numbers (3, 1, -1, +1⁄2) and absorbs infrared radiation of wavelength 1095 nm.

(i) To which energy level does the electron move?

(ii) Calculate the frequency of this radiation.

The photochemical formation of molecule Z uses a radiation of 300 nm. The sample is  irradiated with 100W of this radiation. The quantum yield is 0.2. If the sample absorbs only  50% of the radiation falling on it, then find the amount of Z formed in one second

A fossil gives 435 disintegrations per g of carbon during 1 h of counting. The age of the fossil given that the living matter contains 1.5x10^-12 g of ¹⁴C per g of carbon and that the half life of beta decay of ¹⁴C is 5680yr, will be

Data Table Molarity of Na2S2O3 0.125 M

Initial Buret Reading (Na2S2O3) 1.50 mL

Final Buret Reading (Na2S2O3) 14.35 mL  

Assume the density of the commercial bleach is 1.08 g/mL. Calculate the average percent by mass of NaClO in the commercial bleach.

Cl2 (g) + 2OH- (aq) → ClO- (aq) + Cl- (aq) + H2O (l)          Equation 1

2H+ (aq) + ClO- (aq) + 2I- (aq) → Cl- (aq) + I2 (aq) + H2O (l)      Equation 2

I2 (aq) + I- (aq) → I3- (aq)                                         Equation 3

I3- (aq) + 2S2O32- (aq) → 3I- (aq) + S4O62- (aq)                   Equation 4

The reaction of triiodide with thiosulfate produces the dithionate ion, S4O6 2-. Calculate the oxidation number for sulfur in this ion. Calculate (and show your work) the average oxidation number of S in this ion

Data Table Molarity of Na2S2O3

0.125 M Initial Buret Reading (Na2S2O3)

1.50 mL Final Buret Reading (Na2S2O3) 14.35 mL 

Assume the density of the commercial bleach is 1.08 g/mL. Calculate the average percent by mass of NaClO in the commercial bleach. 

A student has carried out a moving boundary experiment using K₂SO₄ as an electrolyte.

The data obtained was tabulated in the following Table.

Cation velocity 11.43 mms-1

Cross sectional area of tube 28.56 mm²

Transference number of cation 0.593

Anion concentration 0.025 mol dm^-3

Calculate the current flow for the boundary moves as far as 45 mm.

How many grams of each product result from the following reac-

tions, and how many grams of which reactant are left over?

(a) 11.3 g NaCl2 + 13.5 g AgNO32 ¡1x g AgCl2 + 1y g NaNO32

(b) 12.65 g BaCl22 + 16.78 g H2SO42 ¡1x g BaSO42 + 1y g HCl2

A student has conducted an experiment to measure the conductivity of electrolyte Y2SO4 and was found to be 0.147 Ω‒1 m‒1 . This solution was prepared by reacting 23.50 mL of 0.012 mol dm‒3 of H2SO4 and YOH that gives the total volume of reaction mixture is 50 mL.

(a) Write the chemical equation for the reaction.

(b) Find the concentration of YOH

(c) Find the limiting molar conductivity of Y ion