A 22.617 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 70.407 g of water. A 10.883 g aliquot of this solution is then titrated with 0.1072 M HCl. It required 29.32 mL of the HCl solution to reach the methyl red endpoint. Calculate the weight percent NH3 in the aqueous waste.
wt% NH3 = ??
Hint: The titration equation shows one mole of HCl reacts with one mole of NH3:
HCl + NH3 <---> NH4^+ + Cl^-
Haven't covered this topic in class yet. How to solve??
This is how I would go about solving this problem.
moles of NH3 in sample= 0.1072M * 29.32 x 10^-3L=3.14 x 10^-3 moles of NH3.
Remember, the mole ratios are equal since it takes one mole of NH3 to react with one mole of HCl.
3.14 x 10^-3 moles of NH3*(17.031g NH3/ 1mole)= mass of NH3
(mass of NH3/mass of aliquot sample)= ratio of NH3 in sample after it was diluted
ratio of NH3 in sample after it was diluted* total weight after dilution= total mass of of NH3 in sample
(total mass of of NH3 in sample/22.617 g sample of aqueous waste)*100= wt% NH3
*****I left a note for you in one of your other posts about a correction.
To solve this problem, we can use stoichiometry and the concept of equivalence points in titrations. Here's how you can approach it step by step:
1. Start by calculating the number of moles of HCl used in the titration. To do this, multiply the volume of the HCl solution used (29.32 mL) by its molarity (0.1072 mol/L):
Moles of HCl = Volume of HCl (L) × Molarity of HCl (mol/L)
Convert the volume to liters by dividing it by 1000:
Moles of HCl = 29.32 mL ÷ 1000 mL/L = 0.02932 L
Moles of HCl = 0.02932 L × 0.1072 mol/L = 0.003143 moles
2. From the balanced equation given (HCl + NH3 <---> NH4^+ + Cl^-), we can see that one mole of HCl reacts with one mole of NH3.
Therefore, the number of moles of NH3 in the sample is also 0.003143 moles.
3. Now, we need to find the weight of NH3 in the sample. To do this, we'll use the formula weight percent:
Weight percent = (Weight of NH3 / Total weight of the solution) × 100
The total weight of the solution is the sum of the weight of the waste sample (22.617 g) and the weight of water added (70.407 g):
Total weight of the solution = 22.617 g + 70.407 g = 93.024 g
So, we need to find the weight of NH3.
4. To find the weight of NH3, we'll use the molar mass of NH3, which is 17.03 g/mol.
Weight of NH3 = Moles of NH3 × Molar mass of NH3
Weight of NH3 = 0.003143 moles × 17.03 g/mol = 0.05346 g
5. Now, we can substitute the values into the weight percent formula:
Weight percent = (0.05346 g / 93.024 g) × 100
Weight percent ≈ 0.0575%
Therefore, the weight percent NH3 in the aqueous waste is approximately 0.0575%.
To solve this problem, we can use the concept of stoichiometry, which relates the amount of reactants and products in a chemical reaction. Here are the steps to calculate the weight percent of NH3 in the aqueous waste:
Step 1: Calculate the number of moles of HCl used in the titration.
To do this, you need to use the volume and concentration of HCl used.
Given:
- Volume of HCl used = 29.32 mL = 0.02932 L
- Concentration of HCl = 0.1072 M
Use the equation moles = concentration × volume to find the number of moles of HCl used:
moles HCl = 0.1072 mol/L × 0.02932 L
Step 2: Calculate the number of moles of NH3 in the aliquot.
To do this, you will use the stoichiometry of the reaction between HCl and NH3.
Given:
- Reaction stoichiometry: 1 mole of HCl reacts with 1 mole of NH3
Since the molar ratio between HCl and NH3 is 1:1, the number of moles of NH3 is equal to the number of moles of HCl used.
moles NH3 = moles HCl
Step 3: Calculate the number of grams of NH3 in the aliquot.
To do this, you need to convert the moles of NH3 to grams using the molar mass of NH3.
The molar mass of NH3 (ammonia) is:
- Nitrogen (N) molar mass: 14.01 g/mol
- Hydrogen (H) molar mass: 1.01 g/mol (3 H atoms in NH3)
Molar mass of NH3 = (14.01 g/mol) + (3 × 1.01 g/mol)
Then, calculate the mass of NH3 in the aliquot:
mass NH3 = moles NH3 × molar mass of NH3
Step 4: Calculate the weight percent NH3 in the aqueous waste.
To do this, you need to consider the original sample and the dilution made before the titration.
Given:
- Mass of the original sample = 22.617 g
- Mass of the added water = 70.407 g
The total mass of the diluted solution is:
total mass = mass of the original sample + mass of added water
Finally, calculate the weight percent NH3:
wt% NH3 = (mass NH3 / total mass) × 100%
That's the step-by-step process to calculate the weight percent NH3 in the aqueous waste. Now you can substitute the given values into the equations to find the answer.