EXAMKRACKERS Gen CHM #117

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dreamer67

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Not understanding the solution to this problem How does a high molarity indicate a low molecular weight?

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Not understanding the solution to this problem How does a high molarity indicate a low molecular weight?

It would be helpful if you put up the question and perhaps the full answer explanation... I think I have a different edition and my #117 for EK gen chem is about finding how many moles of O2 gas are required to burn one mole of glucose...:confused:
 
Not understanding the solution to this problem How does a high molarity indicate a low molecular weight?

Lets say you have 12g each of substance A & B. But Substance A has a MW of 3g/mol and substance B, a MW of 4g/mol. Substance A (lower MW) will have higher molarity in solution, and a higher osmotic pressure in the case of Qs 117.

How? Sub A has MW of 3g/mol, so based on a 12g sample, it has 4 mols. In a 10 L solution, it will have 0.4M WHILE Sub B has a MW of 4g/mol, so based on a 12g sample it will have 3 mols. And in a 10L solution, the molarity is 0.3M. So, holding everything else constant, a smaller MW substance (sub) has a higher molarity. And in the case of osmotic pressure, O.P. = MiRT, as the molarity goes up, osmotic pressure goes up as well.
 
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