how to calculate molarity ?

Question

how to calculate molarity from 0.2 % w/v of Cefroxadine

 

Answer 1

Hey Tharahpi,

This is a dimensional analyses problem, what you want to find out is how to go from g/L to moles/L, it'll look like this:

(.002gcefroxadine/100Lcefroxadine)(1molcefroxadine/Xgcefroxadine)

 

 

Answer 2

molarity is moles per liter 

 

.2% w/v means mass per volume.

so you need to change mass into moles. you need to find the molar mass of Cefroxadine. if you are lucky, they may give you the molar mass. if you are less lucky, they may give you the chemical formula. in that case, you can use the periodic table calculate the molar mass. if you have more questions on each step, just ask.