How molarity and mass fraction are related? [closed]








**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
 
 






---








 **Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistry Stack Exchange?](https://chemistry.meta.stackexchange.com/questions/141/how-do-i-ask-homework-questions-on-chemistry-stack-exchange)




Closed last year.








[Improve this question](/posts/163863/edit) 




> 
> Concentrated sulfuric acid contains very little water, only $5\,\%$ by mass. It has a density of $\pu{1.84 g mL-1}$. What is the molarity of this acid?
> 
> 
> 


I know to use the molarity $c$ is in $\pu{mol L^-1}$ and that the solution is $95\,\%$ acid and $5\,\%$ water by mass. I am just stuck trying to solve the problem.




If the density of $95\%$ $\ce{H2SO4}$ is given as $\pu{1.84 g mL-1}$ and its molar mass is $\pu{98.08 g mol-1}$, you may do following conversion since units of molarity is $\pu{mol L-1}$ (suppose it is $M$):


$$ M = \frac{\pu{1.84 g}\text{ of solution }}{\pu{ mL}\text{ of solution }} \times \frac{\pu{95 g} \text{ of } \ce{H2SO4}}{\pu{100 g}\text{ of solution }} \times \frac{\pu{1000 mL}}{\pu{L}}\times \frac{\pu{1 mol}}{\pu{98.08 g}} = \pu{17.8 mol L-1}$$


 1