If the mole fraction of nitric acid (hno3) in an aqueous solution is 0.275, what is the percent by mass of hno3?

Hello!

To calculate the percent by mass of HNO₃ we have to assume that we have 1 mol of solution to simplify the calculations and in that way know more easily how many moles of HNO₃ and water are in the mixture. 

If there's 1 mol of solution, then there are 0,275 moles of HNO₃ and 0,725 moles of H₂O. Now we calculate the grams of each one using the molar mas:



To finish, we calculate the percent in mass in the following way:



So, the percentage in mass of HNO₃ is 57,04%

Have a nice day!

It’s b. mass i searched it up