Sunday, February 12, 2012

measurement and calculation

sample 1:
CuO-->   Cu= 1               Cu/ total> 100= 64/80= 80%Cu/20%O
                O= 1*16
sample 2:
Cu2O-->  2*64  128         128/144> 100= 89%Cu/ 11%O
                 1*16  16                                  
                           144 g/mol
Step by step process. . .
Write a balance chemical equation and identify the knowns and the unknowns.
25.0    50.0g  --->  ?g
P'4(s)  +  50'2(g) ---> P'4O'1O(s)

Determine the number of moles of the reactants by multiplying each mass by the conversation factor that relates moles and mass, the inverse of molar mass.
25.0 gP'4 * 1 mol P'4/123.9 g P'4 = .202 mol P'4
50 g O'2 * 1 mol O'2/32 g O'2= 1.56 mol O'2

Calculate the actual ratio of available moles of 0'2  and available moles of P'4.
1.56 mol O'2/.0202 mol P'4 = 7.72 mol O'2/ 1 mol P'4
Determine the mole ration of the two reactants fomr the balanced chemical equation.
5 mol O'2/ 1 mol P'4

Because 7.72 mol O'2 is available but only 5 mol is needed to react with 1 mol P'4, O'2 is in excess and P'4 is the limiting reactant. Use the moles of P'4 to determine the moles of P'4O'10 that will be produced.

Multiply the number of moles of P'4 by the mole ratio of P'4O'10 (the unknown) to P'4 (the unknown)
.0202 mol P'4 * 1 mol P'4O'10/1 mol P'4 = .202 mol P'4 O'10

and then i will add the yellow paper from the scanner in class. . .

Monday, February 6, 2012

How much water is in popcorn. . . .

In this lab we were suppost to find the mass of water loss from the certain amount of popcorn and calculate what percent of the original mass was the water given off in the popping. First we got a 1000-ml beaker and covered at the bottom with vegetable oil. Put foil over the top and it weighted 221 1/2 grams. Then we added exactly 28 corns and then it weighted at 225 grams. Pocked holes into the top of the foil then we lit that baby up. After all the popcorn was popped we let it set to cool and then weighted it at 2221/2 grams. We got that 1.9% of water was given of the popping.  mm then we got some popcorn for everyone:) it was a very good day lol