How do barometric pressure and altitude effect the mass of a substance?

Question

In my chemistry class we did a density lab, calculating mass and volume of a certain colored cylinder. In our report, we have to discuss one source of error not relating to human error or equipment error. I was thinking that either barometric pressure or altitude might affect the outcome, but I'm not really sure what else could have had an affect. Any help would be much appreciated!

Answer 1

Its like thomas says, the pressure, heat or altitude will not effect the mass. but will effect the volume. as the volume decreases then the density is of course higher. do you understand how that works? Heat will expand a volume, cold will shrink it. Pressure increases will shrink a volume. what does a lower pressure on an object do? Think of a balloon with pressure on the outside.
Now as you go to higher altitudes, the force of gravity decreases. If you are using a spring scale wich measures force then your weight measurement would be wrong. Less force means less weight. But not less mass. A Balance scale would measure accurately because it compares two masses to the same force. If the force is lower a 10 kg weight might only weigh 9 kgf. But blancing it against another known 10 kg mass shows it to be a proper 10 kgm instead of 9 kg. Does this make sense?
So now you have your two errors. One caused by pressure changes, the other by Gravity Field changes. Both are related to altitude.
Heat changes happen as you go higher also. Generally hot things expand and cold things shrink. Higher altitudes tend to have lower temperatures. So things might be colder when you measure them. Do you understand what this could mean if you were measuring density. Your measurement of density would be right but only for that temperature. If you were comparing to a standard density you would need to correct your measurement.
So no actual changes in the mass but changes in the volume mean changes in density readings and incorrect measuring of weight instead of mass gives a false density also. If you got all that you have enough for now. As a side note the gravity field fluctuates all over the surface of the earth and gravity meters are important tools in oil prospecting. Knowing about the difference between mass and weight do you think you could design a gravity meter. What would be easier to keep constant, the mass or the length of the spring measuring the weight( force of gravity) on that mass.

Answer 2

No effect on the mass of an object but will effect the volume of a gas

Answer 3

Sorry. Neither altitude not barometric pressure affects mass.

Answer 4

Yes it can. Pressure exerted on the mass will have effect. Altitude changes due to the O2 & pressure.

Answer 5

yup

PV/T

Pressure, Volume , Temperature

all of those effect it
density= mass/volume I think

Answer 6

i hope your stuff stayed the same the whole way through, because mass never changes, and only if you have a balloon would your volume change.