posted by Blair .
i always get the error analysis section of my lab wrong so i need a NON human error in an experiment involving the diffusion of gases
Experiment: stick cotton ends of a Q-tip (one soaked in HCl and one in NH3) into either end of a drinking straw and measure where precipitate is
Could a temperature differential between ends of the straw affect the point of NH4Cl pptn? (It could if the straw was long enough, if one end of the straw was held longer than the other during insertion of the Q-tip, or if the straw was unequally cooled/heated by an air conditioning/heating duct.) I'm sure you did not get an extremely fine line (small width) because there was some intermingling of fumes AND because it takes a finite time for the NH4Cl powder to settle. You can use these two as a starting point. The first one is a little far-fetched. The second one is real but not a very large source of error. However, the shorter the straw the larger percentage this error becomes.