Question

Ammonium nitrate (NH4NO3) is a common component of fertilizer because it is a great source of two nitrogen-containing ions that

easily dissolve into water. A large batch of this liquid fertilizer is made by adding 1.75 pounds of ammonium nitrate to 31.00 gallons of water. What is the molarity of this solution? (Hint: 1 lb. = 454 g and 1 gal. = 3.79 L.)

Answer 1

8.45*10^-2 M

Step-by-step explanation:
(note: I prefer rounding sig figs in the end, not along answering the question.)

The molarity can be calculated by:
M=number of moles/total amount of liquid in liters or M=n/v

To find the number of moles, the number of grams needs to be found first.
1.75 pounds = 1.75 * 454 grams = 794.5 grams.
So, there is 794.5 grams of NH4NO3.
To find the number of moles from grams, divide the number of grams by the molar mass. The molar mass of NH4NO3 is 80.043
794.5/80.043 = 9.926 moles.

The number of liters can be found by multiplying the number of gallons by 3.79 liters per gallon.
31*3.79 = 117.49 liters

From M=number of moles/total amount of liquid, assume that the ammonium nitrate doesn't change the volume of the liquid.
amount of liquid = 117.49 liters
number of moles = 9.926 moles

9.926/117.49 = 0.0844837859 M = 8.45*10^-2 M