For the past week, we've been studying Moles. Today I want you to work on the equations in the computer lab. For the molecules listed below, determine:
How many grams are in a mole.
How many moles are in a gram.
What the percentage of each element is in the formula.
We've done this before with the elements in the back of the room. Now you're going to do it with molecules. Let us take water as an example. How many grams are in a mole of water?
H = 1.0079 amu
O = 15.999 amu
There are two Hydrogens in Water.
Therefore, 2(1.0079) + 15.999 = 18.015 amu.
Now, transfer that directly into grams for the Molar Mass, and a mole of water weighs 18.015 g.
Next, determine how many moles would be in one gram. Again, we did this in the lab yesterday. Take water's mass in grams, and divide it into one, such that 1/18.015 = 0.0555 moles.
Lastly, figure out what the percentage of each element is in the molecule. This is easier than you might expect. Take the individual masses of each element, and divide them by the overall mass.
H2 = 1.0079 * 2 = 2.0158 g
O = 15.999 g
H2 + O = 18.0148 g
H2/H2O = 2.0158 / 18.015 = 0.1119 or 11.19%
O/H2O = 15.999 / 18.015 = 0.8881 or 88.81%
Please do all three steps for each molecule. But I don't want you left unsure as to what to do, and if you are doing this correctly. Therefore, when you have completed all equations for each molecule, after each molecule, go to this website to doublecheck your work. About halfway down the page you can plug in formulas to get all of this data, to get the correct answers. Be sure to use the correct capitol or lower case letters as needed. (You certainly could just fill in the correct answers from this website, but then...I'm also asking you to show all work for each step.)
Following is a list of the molecules I'd like analyzed:
He
O2
C6H12O11
H2
LiOH
H2PO4
H2SO4
PCl5
SF6
NaCl
CsC2H3O2
NH4ClO
Li2CO3
NCl3
BCl3
N2O3
Cl2O7
CO2
Oh- and this assignment is due at the end of the period, to hand in to Mr. 'iissa, so you better get cracking! :-)
