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Question about Gen Chem
Started by nt4reall
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maybe since molality is the number of moles of solute per kilogram of solvent.
# moles of solute:
lets use 1 mL of solution
1 mL solution weighs 1.7g 85% of which is H3PO4 which gives us 1.45g H3PO4. convert to Moles: 1.45/98=.015mol
Kg Solvent:
in 1 mL there is 1.7g solution.
this is .0017 Kg solution.
Molality=mol solute/Kg solvent
=.015mol/.0017 Kg=8.82m
# moles of solute:
lets use 1 mL of solution
1 mL solution weighs 1.7g 85% of which is H3PO4 which gives us 1.45g H3PO4. convert to Moles: 1.45/98=.015mol
Kg Solvent:
in 1 mL there is 1.7g solution.
this is .0017 Kg solution.
Molality=mol solute/Kg solvent
=.015mol/.0017 Kg=8.82m
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0.017mol over 0.001kg = 17.34molality.
but it's 85% so times 0.85 should give 14.74molality
I don't understand why drgreen didn't apply 85% to kg of solvent.
but it's 85% so times 0.85 should give 14.74molality
I don't understand why drgreen didn't apply 85% to kg of solvent.
Last edited:
i'll try at this
i dont know if this is right
but
(85g/100g)(mole/98g)(1.7g/ml)(10^3ml/L)=14.7 M
hard to show, but everything cancels but Mole/L
and it is the same as if you leave out the 85/100 and later pretend it is like 17.3 M represents 100% so 85% is then 14.7M
i dont know if this is right
but
(85g/100g)(mole/98g)(1.7g/ml)(10^3ml/L)=14.7 M
hard to show, but everything cancels but Mole/L
and it is the same as if you leave out the 85/100 and later pretend it is like 17.3 M represents 100% so 85% is then 14.7M
