Question

Part A:
The electrical conductivities of the following 0.100 M solutions were measured in an apparatus that contained a light bulb as the indicator of conductivity. Rankthe solutions in order of decreasing intensity (brightest to dimmest) of the light bulb.
Rank from brightest to dimmest bulb. To rank items as equivalent, overlap them.


HF,CH3OH, KI, Al(NO3)3

BrightestDimmest






Part B:

A 0.100 M solution of K2SO4 would contain the same total ion concentration as which of the following solutions?

0.0800
0.100
0.0750
0.0500

Answer 1

c

Answer 2

Part A:

When molecules ionize they are able to conduct an electrical charge. The amount of charge they can carry is proportional to how complete the molecule ionizes (this is proportioanl to equilibrium constant of reaction) and the number of molecules that ionize in free solution.

All nitrates ionize in water

All alkali and alkali earth metal (Li, Na, K...) ionize completely

Brightest

Al(NO3)3 - ionizes completely, 4 ions total

KI - ionizes completely, 2 ions

HF - Partially ionizes so it would conduct very little (2 ions)

CH3OH - methanol interacts by hydrogen bonding to produce a current since very little dissociates in comparison to HF

Dimmest

 

Part B:

K2SO4 ionizes completely so the ionic molar concentration is .300 M

Na3PO4 ionizes completely (4 molecules) to have an ionic concentration of .300 M

>.0750 M (4 ions) = .300 M ionic concentration