Comments on: Can Someone Help Me With My Stoichiometry Problems In Chemistry?

By: coza b

coza b — Wed, 13 May 2009 04:58:41 +0000

8.
All water evaporated = water loss = 11.88 - 7.6 = 4.28 g.
moles of water = 4.28/18 = 0.2378 moles
13.
Molecular weight
CaF2=78
HF=20
source: http://www.uwosh.edu/faculty_staff/kedro...
percent yield = actual yield/theoretical yield
theoretical yield = 2x(9/78)moles = 0.2308 (based on coefficients, 1 mole of CaF2 produce 2 moles of HF)
actual yield = (1.76/20)moles = 0.088
percent yield = 0.088/0.2308 = 38.12%
16.
Atomic weight of Fe = 56
mol weight of Fe2O3 = 160
4Fe + 3O2 –> 2Fe2O3
Fe stays as Fe = 7/8×627 = 548.625
Fe become Fe2O3 = 1/8×627 = 78.375 ==> 78.375/56 = 1.4 moles,
Fe2O3 = 2/4 x 1.4 moles x 160 = 112 g
total wt = 112+548.625= 660.625 g
17.
assume all glucose become energy+water+Co2
(mol wt=180)
C6H12O6 + 6O2 –> 6CO2 + 6H2O
300 g/day
total CO2 = 6 x (300/180) moles/day x 365 days/year x 6 billion x 44 g/mole CO2
= 9.636 x 10^14 g/year
23.
Mr Fe2O3 = 160 g/mole
1000 kg Fe = 1000/56 kmoles
Fe2O3 needed = 1/2 x 1000/56 = 1000/112 kmoles
Fe2O3 needed = 1000/112 x 160 = 1428.57 kg
purity = 1428.57/2250 = 63.492%

By: Dani

Dani — Wed, 13 May 2009 04:58:41 +0000

sorry, you should go talk to your teacher BEFORE school not before or after class or during either you lose brownie points for that you gain for before school

By: neonpony

neonpony — Wed, 13 May 2009 04:58:41 +0000

i would like to help you but i cant see the questions

By: ME2010

ME2010 — Wed, 13 May 2009 04:58:41 +0000

I need some help with that stuff as well. I can do some stoichiometry, and from my understanding it’s basically converting the grams you want to moles, then multiplying that by the ratio, then multiplying it back to grams.