Final answer:
The molarity of the 30% mass NH3 (aq) solution with a density of 0.9 g/mL is 0.142 M.
Step-by-step explanation:
The molarity of a solution can be calculated using the formula:
Molarity (M) = moles of solute / volume of solution (in liters)
In this case, we need to convert the mass of NH3 to moles and determine the volume of the solution.
Given:
- Mass of NH3 = 30% of the solution's mass
- Density of the solution = 0.9 g/mL
- Molar mass of NH3 = 17.03 g/mol
To determine the moles of NH3:
Mass of NH3 = mass of solution * percentage of NH3 / 100%
Volume of Solution = mass of solution / density of solution
Now, using the values obtained, we can calculate the molarity:
Moles of NH3 = mass of NH3 / molar mass of NH3
Molarity = Moles of NH3 / Volume of Solution
Substituting the values, we get:
Moles of NH3 = (mass of solution * percentage of NH3 / 100%) / molar mass of NH3
Molarity = [(mass of solution * percentage of NH3 / 100%) / molar mass of NH3] / (mass of solution / density of solution)
Simplifying the expression, we get:
Molarity = (percentage of NH3 / 100%) * density of solution / molar mass of NH3
So, the molarity of the 30% mass NH3 (aq) solution with a density of 0.9 g/mL is (30% / 100%) * 0.9 g/mL / 17.03 g/mol = 0.142 M