Percent error formula

Percent Error Formula is to calculate how far we have gone in our experimental value from the theoretical value. Often if our

lab sample contain water, impurity or have loss during the experiment, the percent error is either too big ( too much water) or just below the theoretical value. (loss during transfer)

Conclusion could be based on human error, exposure to humility, or final products does not have enough time to dry etc. They can all be different.

Percent Error Formula

Percent error: (Formula) These number we calculate is to give our lab report an explanation why things happen and what has gone wild!

Experiment value = the product value your wrote down, has same unit with theoretical value. Mostly = g

Theoretical value = obtain from the pre-lab. The idea is "what is supposed to come out it from the end of experiment." Normally we have 1 to 1 ratio in balancing formula in lab, so the mole of the reactant should = the mole of product

Percent error can be big number if the sample is not dry, but if something like 868% coming out, I would check again if the molecular weight was used correctly.

Percentage yield

Percentage yield is different from percentage error. Error is one step after percentage yield. Both explain what exactly happen.

Actual yield = is what we got in the end of experiment.

Theoretical yield = we calculate in the pre-lab. Based on 1:1 ratio, use anticipated

(moles of products) x (molecular weight )

Lazy way... if this is 1:1 ratio, I can just find the moles of the reactant x the molecular weight of product)

Since actual yield is unit "g", theoretical yield is also use the unit "g". ( if not gram, then the other would not bee "gram")

Note: Mole = g/molecule weight

Formula for density is straightforward. One note: Mass is in "g" and volume is in "L"

Comments

-1 #19 RE: Percent error formula — bing bing 2010-08-19 07:05

Quote

-4 #18 percentage error — ardie 2010-08-07 20:08

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