an aqueous solution of ammonia has 0.8% NH3 by weight.calculate the NH3 molarity

And the density is?

To calculate the NH3 molarity (M), we need to know the molar mass of NH3 and the density of the solution.

The molar mass of NH3 (ammonia) is:
M(N) = 14.01 g/mol
M(H) = 1.01 g/mol
M(NH3) = M(N) + 3 * M(H) = 14.01 + 3 * 1.01 = 17.03 g/mol

Given that the solution has 0.8% NH3 by weight, we can determine the amount of NH3 in grams present in 100 grams of the solution:
mass_NH3 = 0.8 g

Now we can calculate the number of moles of NH3:
moles_NH3 = mass_NH3 / M(NH3)

Finally, to determine the molarity (M), we need to know the volume of the solution in liters. Assuming it is 1 liter:
M = moles_NH3 / volume_solution

Therefore, to calculate the NH3 molarity, divide the mass of NH3 by the molar mass, then divide by the volume of the solution in liters.