Graham's law. In this experiment the relationship between the molar mass of a gas and the speed with which it diffuses was to be assessed.

Purpose

        To demonstrate the relationship between the molar mass of a gas and the speed with which it diffuses.

Materials

In the hood: NH3 17 M, HCL 12M

Cotton swabs

Acetone

Glass tube(60 cm in length)

Meter stick

Procedure

        First, three glass tubes were placed on a level table. Next, in the fume hood, an end of the cotton swab was soaked into the 12 M HCl and another in the 17 M NH3. After being soaked for a brief period of time each were inserted simultaneously into opposite ends of one of tubes and covered with paper towels to prevent excess air flow. This was repeated twice and a white ring participate was formed.  The distance of this ring to both ends is then measured and recorded.

Data

Calculations

Molar Masses of NH3 and HCl

NH3 = 17

HCl = 36.4

Conclusions

In the experiment, the molar mass of our gases was 17 for NH3 and 36.4 for the HCl.  In terms of validating Graham’s Law our experiment did in that because we demonstrated that the NH3 diffused faster. This coincides with Graham’s Law because the lighter the gas the faster it diffuses.

Further Questions

1. If the temperature was changed then nothing will occur because according to Graham’s law temperature is not a factor. However, if the molar masses were changed then the rate will changed in an inversely proportional matter.

b)

oxygen r1 = 1.03r2

1.03r2/r2 = sq. root (m2/32)

1.03 = sq. root (m2/32)

1.06 = m2/32

33.95 = Unknown gas