A solution contains 23.1 ppm of dissolved Fe(NO3)3 (241.860g/mol), which dissociates completely into Fe3+ and NO3- (62.005g/mol) ions. Find the concentration of NO3- in parts per million
For every one Fe(NO3)3 molecule you have you get three NO3^- ions when the molecule dissociates. So the (NO3^-) is 23.1 ppm x 3 = ?
To find the concentration of NO3- in parts per million (ppm), we need to understand that ppm represents the number of parts of solute per million parts of the solution. In this case, the solute is NO3-, which we know is formed by the dissociation of Fe(NO3)3.
First, we need to calculate the concentration of NO3- ions in moles per liter (Molarity). The molarity (M) is calculated by dividing the number of moles of solute by the volume of the solution in liters.
Given that the molar mass of NO3- is 62.005 g/mol, and the molar mass of Fe(NO3)3 is 241.860 g/mol, we can find the number of moles of NO3- in 23.1 ppm of Fe(NO3)3.
To do this, we will convert ppm to mg/L, then to g/L, and finally to moles/L using the following steps:
Step 1: Convert ppm to mg/L:
1 ppm = 1 mg/L
So, 23.1 ppm = 23.1 mg/L
Step 2: Convert mg/L to g/L:
1 g = 1000 mg
So, 23.1 mg = 23.1/1000 = 0.0231 g
Therefore, 23.1 mg/L = 0.0231 g/L
Step 3: Convert g/L to moles/L:
Using the molar mass of NO3- (62.005 g/mol), we can calculate the number of moles:
Moles of NO3- = Mass of NO3- / Molar mass of NO3-
Moles of NO3- = 0.0231 g / 62.005 g/mol
Moles of NO3- = 0.000372 mol
Finally, we have the molarity (moles/L) of NO3- in the solution.
To convert this to ppm, we can use the fact that 1 ppm = 1 mg/L.
Converting moles/L to ppm:
1 mole = molar mass in grams (g)
1 L = 1000 mL = 1000 g
So, 1 mole/L = molar mass in grams (g) / 1000 g/L
Using this conversion factor, we can calculate the concentration of NO3- in ppm:
Concentration of NO3- in ppm = Moles of NO3- / 1 L * (molar mass of NO3- / 1000 g/L)
Concentration of NO3- in ppm = 0.000372 mol/L * (62.005 g/mol / 1000 g/L)
Concentration of NO3- in ppm = 0.000372 * 62.005 ppm
Concentration of NO3- in ppm ≈ 0.023 ppm
Therefore, the concentration of NO3- in the solution is approximately 0.023 ppm.