Calculating Molarity: A student needs to make 0.755 L of a sodium bromide solution for an experiment. The concentration of the required solution is 0.450 M. How many grams of sodium bromide will she need to use?

Question

imqwerty · Answer

okay so do you know the formula to find molarity? :)

imqwerty · Answer

@chemhelppleasees

anonymous · Answer

M = mol / liter?

imqwerty · Answer

yeah :)
$\large M = \Large \frac{n}{L}$ 

here 
$M=molarity$
$n=number~of~moles$
$L=volume~in~liters$ 

okay so now tell how do we calculate number of moles

anonymous · Answer

I'm not sure but is this how you would set it up $$0.450 = x/0.755$$?

imqwerty · Answer

yeah thats correct

can you find $x$  from here

anonymous · Answer

x = .33975

imqwerty · Answer

yes correct
now we have the number of moles=0.33975
now we gotta find mass of $NaBr$ used

anonymous · Answer

If the molar mass of NaBr is 102.894 would you multiply that by .33975 to get 34.958?

imqwerty · Answer

try to use this formula-
$\large moles= \Large \frac{mass}{Molar~Mass}$ 

you know the number of moles
Molar mass of $NaBr$ is 102.89

just put them to get the mass of $NaBr$

imqwerty · Answer

yea you are correct you gotta multiply them up
and your answer is also correct :)

anonymous · Answer

Okay, thank you for your help!

imqwerty · Answer

np :)