as soon as preparing a known mass of something (e.g. When producing a traditional solution) it is regularly that in my college lab the we first use a weighing watercraft to measure the mass and then when transferred right into a beaker we reweigh the boat and calculate the mass transferred.

Do us this even though us zero the range anyway?

Now to my expertise would this not boost the apprehension as rather of just using the maker on the range and including the mass straight which would cause one suspicion we rather weigh it double which would certainly thus have actually 2x the hesitation in the scale.

Could somebody explain where my reasoning is wrong and also why this technique is more accurate?

You are watching: Why do you weigh by difference

improve this question
edited Jun 24 "17 in ~ 1:47

2,50022 yellow badges1919 silver badges4747 bronze title
inquiry Jun 23 "17 at 19:20

Jake RoseJake rose
17111 silver badge22 bronze badges
add a comment |

2 answers 2

active oldest Votes

See more: How Much Does A Styrofoam Cup Weigh T Conversion, Weight Of Styrofoam Cup

Although there are numerous sources of weighing error that would certainly be decreased by using the weighing through difference method (as disputed in the comments), I want to illustrate what I view as the limiting problem, the of the relative uncertainty of the measurement, which approximately scales (no pun intended, really) v the mass being measured.

Lets use a little bit of one exaggerated instance for illustration. In particular, we"ll say the we have actually one balance that deserve to measure down to $\pu0.001g$, and can handle up to $\pu100g$ complete mass. In truth you would certainly likely have a high-mass balance for weighing straight into the beaker, or a low-mass balance for utilizing the weighing boat. We are just using one really good balance to simplify this illustration, yet the ide is the very same either way.

Lets speak our beaker has a mass of $\pu50g$, our weighing boat is $\pu1g$, and also we space to measure the end $\pu1g$ the material.

The beaker to add the product to it is in measured will certainly then have actually a measured mass of ~$\pu51.00 +/- 0.05g$. This way that the loved one uncertainty in the measured massive of the product is no far better than $\pu5\%$($\pu0.05g$ the end of $\pu1g$).

The weighing boat add to the product to it is in measured the end will have actually a measured massive of ~$\pu2.000 +/- 0.002g$. This way that the loved one uncertainty in the measured mass of the material is $\pu0.2\%$ ($\pu0.002g$ the end of $\pu1g$).

So, also with two dimensions rather than one, utilizing the weighing boat technique results in much less complete uncertainty in the measured mass of your product as contrasted to weighing a little quantity that material straight into a large beaker.