destroyer gchem #35

[yakuza]

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This is the only gchem problem I never understood. Seriously where the hell did he derive this equation from..??? Makes NO sense

A solution of LiCl has a density of 1.13 g/cm^3 at 25'C. If the solution is 20% by weight of LiCl, which is the molarity?

answer: 5.3 M

I really don't want to waste anymore time trying to prove this problem wrong..can someone explain it please?

 

[mistero]

The question asks you to find the molarity, which is mol/liter. You have to figure out how many grams of LiCl (solute) there are in one liter (solution).

The density tells us how many grams of the solvent and solute we have in one ml. if we multiply that by 1000, then we know we have 1130g of solvent and solute per liter.

We now have to figure out how much solute we have from within the solvent and solute. The question tells you that you have a 20% LiCl mixture, which means that for every 100g of solvent, we have 20g of LiCl (the solute). When we multiply this percentage by the density (which we multiplied by 1000 already) we get how many grams of solute there are in one liter of solution.
We now convert grams into moles and it is in moles/Liter and we have our answer.

I hope this was helpful.

 

[joonkimdds]

c'mon Yakuza~ use your Sharingan!!!
molarity = M = mol of solute/L of solution.
THat's it!!!!

 

[yakuza]

c'mon Yakuza~ use your Sharingan!!!
molarity = M = mol of solute/L of solution.
THat's it!!!!

Eh..lol

I have a mental block at this problem