Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: buckminsterfullerene on November 05, 2007, 09:24:42 PM
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errmm.... the packet that is supplying me with the information on how to solve these kind of problems is making little sense to me, and I am supposed to write a lab report on that, can't really accomplish that unless I comprehend what is going on and how do the equations, which at this point seem to be all over the packet, work.
a link to a site that has helpful information is welcomed, but if you know anything to the perspective, please respond, and thanks in advanced.
-Daniel Garcia
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perhaps some information might help.
it seems, after reading the packet a couple times, the main equation to be used in order to determine is going to be:
n(H2) = (0.0556 moles H2 / gAl) * X*gAl + (0.0153 moles H2 / gZn) * (mass of sample - X)
where X is apparently the mass of Aluminum, (mass of Al -X) is the mass of Zinc
that is that for the equation they give that I still have to try and make some sense about.
as for the value that I have acquired through the experimentation, at least the values that are significant:
trial 1
mass of alloy = .104 g
displaced water = 122.5 mL (we are to assume density of the water is 1.00 g/mL to determine the the amount of hydrogen gas available)
the temperature was 22 Celsius (of the water that is)
barometric pressure = 761.4 mm Hg
pressure of water = 19.87 mm Hg
pressure of hydrogen = 741.6 mm Hg
and I am supposed to determine the mass of Al, Zn the percentage of Al and Zn.
I am not asking for you to do the work, but to tell me how this works, I am completely lost...
(P.S. use ideal gas laws... do not get too technical, this is a beginners chemistry course, sort of)
if you feel like giving the response rather than explaining that will also help, I could use a response to try and work it backwards, answers by themselves are pretty useless for me though as I have to also write a lab report explaining everything.
uggh...
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perhaps some information might help.
it seems, after reading the packet a couple times, the main equation to be used in order to determine is going to be:
n(H2) = (0.0556 moles H2 / gAl) * X*gAl + (0.0153 moles H2 / gZn) * (mass of sample - X)
where X is apparently the mass of Aluminum, (mass of Al -X) is the mass of Zinc
that is that for the equation they give that I still have to try and make some sense about.
as for the value that I have acquired through the experimentation, at least the values that are significant:
trial 1
mass of alloy = .104 g
displaced water = 122.5 mL (we are to assume density of the water is 1.00 g/mL to determine the the amount of hydrogen gas available)
the temperature was 22 Celsius (of the water that is)
barometric pressure = 761.4 mm Hg
pressure of water = 19.87 mm Hg
pressure of hydrogen = 741.6 mm Hg
and I am supposed to determine the mass of Al, Zn the percentage of Al and Zn.
I am not asking for you to do the work, but to tell me how this works, I am completely lost...
(P.S. use ideal gas laws... do not get too technical, this is a beginners chemistry course, sort of)
if you feel like giving the response rather than explaining that will also help, I could use a response to try and work it backwards, answers by themselves are pretty useless for me though as I have to also write a lab report explaining everything.
uggh...
n(H2) = (0.0556 moles H2 / gAl) * X*gAl + (0.0153 moles H2 / gZn) * (mass of sample - X)
never mind, that equation just got me really confused, but it was simple after all, I just thought that I had three different unknown values and did not realize that whoever wrote the packer wrote what X was in the equation itself rather then outside, lol.
X is the mass of Aluminum so in reality the equation comes out being
n(H2) = (0.0556)X + (0.0153)(mass of sample - X)
and I would solve for X, very simple indeed, lol.
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so how would go about finding the %Al?
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We are going to do this lab next week and I'm very confused about all those formulas