Hi everyone. I'm having a bit of an issue. It could just be that I did the experiment wrong, but I think my work might also be wrong. I should end up calculating a similar amount of zinc for #1 and #3, but I am getting a massive difference between the two.
This was from a lab, so here are values which may be useful:
Total mass unknown sample: 1.501g
Total volume H2 gas: 423mL
Volume HCl used: 9.60mL
Atmospheric pressure: 73.06mmHg
Water temperature: 280.4K
Vapor pressure water at 280.4K: 7.72mmHg
Calculated conversion factor: 26,500mL H2/mol Zn
Reaction: Zn + 2HCl ZnCl2 + H2O1. Use the conversion factor you calculated earlier to determine the mass of zinc in the unknown sample.volume H2 * conversion factor * molar mass Zn
.423
L H2*(1
mol Zn/26.5
L H2)*(65.41g/
mol) =
1.04g ZnI think I did this one correctly.
2. Calculate the pressure of H2 using Dalton's Law.P
total = P
H2 + P
H2O73.06mmHg = P
H2 + 7.72mmHg
P
H2 = 65.34mmHg
3. Calculate the mass of zinc in the unknown sample using #2 and the ideal gas lawPV = nRT
n = PV/RT
n = (65.34
mmHg*.423
L)/(62.36367
LmmHgmol
-1K-1*280.4
K) = 0.001580555mol H
20.001580555
mol H2*(1
mol Zn/1
mol H2)*(65.41g/
mol) =
0.103g Zn------------------------------------------------------------------
As you can see, 1.04 is nowhere near 0.103. Where did I go wrong? If nothing is wrong, it's possible the conversion factor is wrong. In which case, would you guys mind checking that also if I post it here? Thanks.