Question

An ammonia (nh3) solution composed of 4.00 g nh3 for every 96.00 g water flows into a 305.0 gallon tank. the density of this solution is Ď = 0.9811 g/ml. what is the molarity of this solution?

Answer 1

For conversion, there are 3,785.41 mL for every 1 gallon. 

Volume = 305 gal (3,785.41mL/gal) = 1,154,550.05 mL 

The equivalent mass of the solution would be:
1,154,550.05 mL *0.9811 g/mL = 1,132,729.054 g
Ratio = 1,132,729.054 g/ (96 +4) = 11327.29

Thus, the total amount of solute in the mixture is:
Amount of solute = 4*11327.29 = 45,309.16 g
The molar mass of ammonia is 17 g/mol.
Amount of mol of solute = 45,309.16 g/ 17 g/mol = 2,665.24 mol

Since molarity is mol solute per liter,
Molarity = 2,665.24 mol/[1,154,550.05 mL(1 L/1000 mL)]
Molarity = 2.308 M