Concentrated ammonium hydroxide (aq ammonia) has a density of 0.90g/mL and is 28% by mass ammonia. Determine the molar concentration of ammonium hydroxide.
If it is 28 percent ammonia, then it contains .90*.28 grams ammonia/ml.
or in a liter, 900*.28 grams/liter
divide that by the mole mass of NH2, and you have molarity.
1.47
To determine the molar concentration of ammonium hydroxide, we need to calculate the amount of ammonia present in a specific volume of the solution.
Given:
- Density of ammonium hydroxide solution = 0.90 g/mL
- Mass fraction (w/w) of ammonia in the solution = 28%
First, let's convert the given density into mass per volume:
Density = Mass / Volume
Mass = Density × Volume
Since the density is given in g/mL, we can assign a volume of 1 mL to calculate the mass.
Mass = 0.90 g/mL × 1 mL = 0.90 g
Next, we need to determine the mass of ammonia in the solution:
Mass of ammonia = Mass of solution × Mass fraction of ammonia
Mass of ammonia = 0.90 g × 0.28 = 0.252 g
To calculate the moles of ammonia, we need to use its molar mass. The molar mass of ammonia (NH3) is 17.03 g/mol.
Moles of ammonia = Mass of ammonia / Molar mass of ammonia
Moles of ammonia = 0.252 g / 17.03 g/mol = 0.0148 mol
Finally, to determine the molar concentration (also known as molarity), we need to know the volume of the solution.
The molar concentration formula is:
Molar concentration (mol/L) = Moles of solute / Volume of solution (L)
Since the volume of the solution is not given, we cannot determine the molar concentration without additional information.