Question

Calculate the molality of each of the following solutions.

1. 93.2 g of NaCl in 583 g of H2O

Answer 1

@aaronq

Answer 2

but first you need to convert the mass of solute to moles.

Answer 3

so do i need to get 93.2 into liters and 583 g of h2o into liters?

Answer 4

ahh no, i messed up. i wrote the molarity formula.

it should be: \(molality=\dfrac{moles~of~solute}{kilograms~of~solvent}\)

Answer 5

I'm confused?

Answer 6

i wrote the wrong formula before. This one ^ is right.

Do you remember how to find the moles of something?

\(moles=\dfrac{mass}{Molar~mass}\)

Answer 7

find the moles of the solute first.

Answer 8

wat?

Answer 9

to find the molality of the solution, you need to know the moles of the solute.

find the moles of the solute

Answer 10

so i divide 93.2 over moles and 583 over moles

Answer 11

no, not yet.

you need to know the moles of solute, you only know the mass.

Divide the mass of the solute (the salt) by the molar mass to get the moles.

Answer 12

so divide 58.4425 g/mol

Answer 13

by 22.98

Answer 14

93.2 g/58.4425 g/mol = moles of NaCl

then \(molality=\dfrac{moles~of ~NaCl}{kilograms~of~water}\)

notice that you don't need to find the moles of water, you use the mass

Answer 15

so does 1.5947 go on top or bottom?

Answer 16

look at the formula, it goes on the top.

Answer 17

ok and then 93.2 converts to kilo?

Answer 18

take 583 g and convert it to kg.

Answer 19

it takes 583 equals=0.0583?

Answer 20

583/1000=0.583

Answer 21

then?

Answer 22

so now plug these 2 values into the molality formula.

Answer 23

so 1.5947/0.583?

Answer 24

yes

Answer 25

so its 2.735?

Answer 26

yep! thats it

Answer 27

but wats the unit

Answer 28

"m" (for molality) or "mol/kg of solvent"

Answer 29

is that the final answer?

Answer 30

yes, it is.

Answer 31

ok i have a final question and thank you so much for the help message me ur address i wanna mail u something to make it up to u

Answer 32

no it's all good! no problem

post it!

Answer 33

ok thanks ur really nice