Molarity/dillution

Hello all, today we went over molarity and dilution.  Using molarity is pretty simple if you follow some easy steps.

Primero, remember that molarity= moles solute/liters of solution

Por ejemplo, if you have an equation like : Dissolve 4.00 g of NiCl2 x 6H20 in enough water to make 150 mL of solution.  Calculate the molarity, so first we do what we learned in stoichometry last unit, 4.00 g x 1 mol/ 237.7 g (which is the molar mass) and you will get 0.0168 mol. 

 Entonces you simply follow the formula mentioned previously: 0.0168 mol (the moles solute you found) / 0.150 L (after you convert milliliters to liters) and your final answer is 0.112 M.

For using molarity, remember that moles= mass x volume so simply make any necessary conversions in any given equation, the do the calculations to find moles.  once moles are found.  Convert the moles to grams by multiplying the mols by the g/mol. that is ur final answer.

Ademas, 2 other ESSENTIAL concentration units is Molarity, m which is  :  m of solution= mol solute/ kg solvent
and % of mass= grams solute/ grams solution.  Basically, if you understand the formulas and know them relatively well, all you have to do is make sure your conversions are correct, and you put the numbers in the right places to be multiplied or divided,

Tambien, it is necessary to understand that diluting a solution is just adding more water and therefore the amount of solute stays the same.  Henceforth nb =na  and n= MV .   MbVb=MaVa

Very important in dilution equations is to first find all the variable you know for sure. for example, if in a given equation M1, V1, and V2 are given for sure. all you have to do is simple algebra to solve for M2. once you get M2 you put all 4 variables back into the equation and  ipso facto you have your answer.  In our level of chemistry you are almost always given 3 variables and thus you only have to solve for one.  Don't get caught up over the different letters for variables, because that is just the chemistry gods trying to mess with your brain.   

Finalmente, molarity and stoichiometry equations are literally the same things as mentioned previously.  just find out all the variables you know for sure, solve for the variable you dont know. and make all the necessary conversions.  If you did not receive a 61.6 % on a test like some people did, you should understand it pretty well.  That is all for today, and I hoped i somewhat atoned for my good, but not spectactular showing yesterday.

Hw: Molarity worksheet and begin doing webassigns

Next Scribe= Cody from Stage crew