Concentration of Solution Chemistry Problem?

Question

In each of the two cases, which of the solutions is more concentrated in water? Why (so I can try to do the rest of them on my own)?
a) .500 M KCl or 0.5% KCl
b) 1.75 M glucose or 1.75 m glucose

M is molarity, m is molality

Answer 1

a) usually % indicates weight percent. so your question is this is .5 M (ie Molar) more concentrated that .5% by weight.

You need to get these two on equal grounds.
so.. here goes

first, 0.500 M = 0.500 moles / liter

next

.5%KCl = .005 g KCl/(g solution) = .005 g KCl / (.005 g KCl + .995 g Water)

now if we assume constant volume (and I would for simplicity) so that if we start with .995 g water = .995 ml water and add KCl to it, we would still have .995 ml water. then...

molarity of KCl = moles KCl / liter KCl = mass KCl/ Molecular weight KCl x (1 / volume water)=

.005 g KCl x (1 mole/ (74.5g/mole)) x (1 / .995 ml water) x (1000 ml/ liter) = .0675 Molar.

0.500 M > .0674 M

so 0.500 M KCl is more concentrated

b) M is molarity = moles / liter solution, m is molality = moles / kg solvent

for this you can't ignore volume changes. if you add a solute to a solvent, the volume always increases slightly. so.

1.75 M = 1.75 moles glucose / (1 liter of solution)

but, that 1 liter of solution is < 1 liter of water

whereas 1.75 m = 1.75 moles glucose / ( 1 kg water)
and 1 kg water = 1 liter of water

so 1.75 M is 1.75 moles dissolved in less than 1 liter of water
and 1.75 m is 1.75 moles dissolved in exactly 1 liter of water

so 1.75 M is more concentrated.

Answer 2

a million. iii). {i flow to shrink the concentration and ii won't effect it. a much greater effectual gas rigidity willpersistent greater beneficial into the water. See Le Chatelier's theory} 2. Molality (now no longer molarity) is this variety of moles of solute in keeping with kilogram of solvent (now no longer answer). A 13.80 2 wt% answer is 13.82g in keeping with one hundred g of answer = 13.80 2 g in keeping with 86.18 g of solvent = a hundred and sixty.36g in keeping with kg of solvent a hundred and sixty.36 g of glucose is 0.89 moles, so the molality is 0.89 3. NH4+ is right, yet 2 of them tie up with one SO4, so its SO4--

Answer 3

for those like example a)

calculate the Relative Molecular Mass of both the solute and the solvent and then resolve which solution contains more of the solute per unit volume of water.

type b) I don't understand the difference between M & m