chem

[snowkiller]

i need help with converting moles to mass, mass to mole, percent yield, actual yield, theoretical yield. like i know to do it i just dont get it.

[BFM_Exodus]

n= number of mole
m= mass in grams
M= Molar Mass of element/molecule

n=m/M

When using this formula, ensure that the mass is always in grams, and that you add the molar mass up correctly.

In terms of yields:

Theoretical Yield - The yield you expect to find from the experiment/reaction, assuming the reactions were all 100% complete, all measurements were 100% accurate, and no other mass of any reactants was lost during the experiment. This is all calculated by yourself using the above formula, and all the amounts of the reacting substances that you believed you had BEFORE the experiment. Remember that the maximum amount of any substance you obtain at the end of the experiment is all dependant on the LIMITING REAGENT.

Actual Yield - The yield that you have calculated from figures obtained AFTER the experiment. usually by weighing the precipitate obtained at the end. Generally these two figures should be quite close. Close figures indicates a well conducted experiment.

Percent Yield - Actual Yield/Theoretical Yield. Sort of a measure of how accurate the experiment was.

Limiting Reagent - Using the n=m/M forumla and given information, it is important to determine which reactant you have in the experiment is going to limiting the amount of product you calculate at the end. This is dependant on the Coefficients in front of the reactants according to the equation of the reaction. Example:

xHCl + yNaOH -> zWater + tNaCl

In this case, each of the coefficients required to complete the reaction is one. However this is not always the case. Example:

xH2SO4 + yNaOH -> zWater + tNa2SO4

In the above case x = 1, y=2, z=2 and t=1. This means that you require DOUBLE the amount of NaOH compared to Sulfuric Acid in the reaction. Remember to apply that to your limiting reagent.

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To conclude, the purpose of this simple chemistry and the reasons for the process above is simply to find: If i have so much of A and so much of B, how much do i have of the Product C?

[snowkiller]

oh  i get it now thanks

[BFM_Exodus]

Your very welcome. Hope it helps.

[snowkiller]

it did i got a big pop quiz today and my teacher greaded them and i got an 83%  thanks so much once again 

[Draucus]

well congratulations, snowkiller!

[Goalie]

it did i got a big pop quiz today and my teacher greaded them and i got an 83%  thanks so much once again 

Means this board has potential.

As a college student, I will try and help out my fellow peers as much as I can.  Only if Exodus doesn't beat me to it 

[BFM_Hydra]

Nice work Snowkiller.

[BFM_Warlord]

Exodus you did a fantastic job.I commend you my friend.Thanks for taking time out of your day to help others.That goes for all of you.Please don't be offended if someone helps someone before you can.These people probally need help as soon as they can get it.If someone happens to be on that can help they should.I just don't think anyone should feel bad because they didn't get the chance.Your chance will come.It is also just knowing you want to help that makes a differance as well.