Question

 1. What are the SI units of conductivity?

 a. What is the conductivity of deionized water?

 b. What is the conductivity of tap water?

 c. What is the conductivity of sea water?

 2. What does the conductivity of a solution indicate?

 3. How many milliliters of concentrated sulfuric acid are needed to make up 1.00 liter of 0.080 M sulfuric acid? (Note: a volumetric flask is employed for the dilution.)

 4. How many grams of Ba(OH)-8H,O are needed to make up 1.00 liter of 0.010 M barium hydroxide. (Note: a volumetric flask is employed for the dilution.)

 5. Why does the conductivity of the solution initially decrease as the sulfuric acid is added? 6. What does the minimum conductivity indicate?

 7. After reaching a minimum, why does the conductivity of the solution increase as the sulfuric acid is added?

 8. Assume the concentration of the barium hydroxide is unknown. Based on the known concentration of sulfuric acid, what is the concentration of the barium hydroxide? (Assume a 75.0 mL aliquot of the barium hydroxide was used in the titration.)

Answer 1

1 SI unit of conductivty is Siemens/m

b). Conductivity of deionized water = 5.5*10^-3 Siemens/m , c) tap water = 50*10-3S/m and sea water =5 S/m

2. Conductivity of a solution is the ability of material to conduct electricity.

3) Molarity of concentrated sulfuric acid =18.4

18.4*V= 1*0.080 ( from M1V1= M2V2)

V= 1*0.080/18.4=0.004348L= 4.35 ml

4) Molecular weight of Ba(OH)2. 8H2O= 315.77 ( Atomic weights : Ba= 137, O= 16, H=1 )

moles of Ba(OH)2 in 0.01M and 1 L = 1*0.01 = 0.01 moles

1 mole of Ba(OH)2.8H2O contains 315.77 gms of Ba(OH)2. 8H2O

Moles of Ba(OH)2. 8H2O= 0.01*315.77=3.1577 gms

5. The decrease in electrical conductivity is due to the chemical reaction of the sulfuric acid ( strong acid) with the barium hydroxide ( strong base) leading to neutralization reaction

6. In the titration of a strong acid with a strong base, the conductance has a minimum at the equivalence point. This minimum can be used, instead of an indicator dye, to determine the endpoint of the titration

7. the additional sulfuric acid after neutralization ionizes leading to an increase in conductivity.

8. The reaction is Ba(OH)₂+ H2SO4----> BaSO4+2H2O

moles of sulfuric acid in known concentration (let it be M1)= M1*V1/1000

Moles of Barium hydroxide= M2*75/1000 ( where M1 and M2 are molarities of sulfuric acid and Barium hydroxide repsectively)

M2= M1*V1/75