Question

An aqueous solution of 6.70 M ammonia, NH3, has a density of 0.950 g/mL. The percent by mass of NH3 in the solution is %.

Answer 1

12.01% by mass

Step-by-step explanation:

Percent by mass is 100 times the mass of solute (ammonia) over the mass of the solution. In molarity, we have the moles of ammonia per liter of solution. There are 6.70moles of NH3 in 1L. Thus, we need to convert the moles of ammonia to grams and the liters of solution to grams:

Mass ammonia - Molar mass: 17.031g/mol-

6.70moles * (17.031g / mol) = 114.1g NH₃

Mass solution:

1L * (1000mL / 1L) = 1000mL * (0.950g/mL) = 950g

Percent by mass:

114.1g NH₃ / 950g * 100 =

12.01% by mass