1. Questions

Chemistry

25 ml of cloudy ammonia solution is added to a 250 ml Erlenmeyer flask. 50 ml of .1 M HCl is then immediately added to the flask, which reacted with the ammonia in the solution. Next, the solution was titrated with .025 M NaOH to neutralize the excess HCl that was not neutralized by the ammonia. 21.50 ml of NaOH was added to neutralize the excess HCl. Calculate the concentration of ammonia in the cloudy cleaning solution.

  1. 👍
  2. 👎
  3. 👁
Anonymous

  1. NH3 + HCl ==>NH4Cl
    Excess HCl + NaOH ==> NaCl + H2O

    Mols HCl added initially = M x L = 0.1M x 0.050L = ?
    mols NaOH to neutralize excess HCl = M x L = 0.025M x 0.02150 = ?
    mols HCl used by ammonia = mols initially - mols excess = ? = mols NH3 initially.
    M NH3 = mols NH3/L NH3 = mols from above/0.025L = ?

    1. 👍
    2. 👎
    DrBob222

  2. I understand everything except how to calculate the mols NH3? Do the mols of HCL used by ammonia equal the mols of NH3 initially? Also, what is the mols excess that you used to calculate the mols of HCl used by ammonia?

    1. 👍
    2. 👎
    Anonymous

  4. yes.
    The problem in words works out this way. You have so many mols NH3 at the beginning. You had an excess of HCl which reacts with all of the NH3 and leaves extra HCl in the solution. The first thing you want to do is to find the how much excess HCl is there. You do that by titrating the HCl with a known volume and concn of NaOH. The NaOH is used to determined how much excess HCl you had. The mols NaOH used = mols HCl the NH3 DID NOT USE. So the difference in mols HCl you started with minus the mols HCl the NH3 did not use = mols NH3 used.

    1. 👍
    2. 👎
    DrBob222

  5. Oh, okay. I understand now, thank you so much for your help.

    1. 👍
    2. 👎
    Anonymous

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    A student placed 19.0g of glucose (c6h12o6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100ml.- mark on the neck of the flask was reached. The

  2. Chemistry-Please help

    A student placed 11.0 of glucose (C6H12O6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100.-ml mark on the neck of the flask was reached. The flask

  3. chemistry

    Lab: Determining Ka of Acetic Acid Purpose: The purpose of this experiment is to determine the molar concentration of a sample of acetic acid and to calculate its Ka. Materials: phenolphthalein 125 mL Erlenmeyer flask 25 mL pipet

  4. Chemistry

    A 100 milliliter sample of 0.100-molar NH4Cl solution was added to 80 milliliters of a 0.200-molar solution of NH3. The value of Kb for ammonia is 1.79 x 10^-5. (a) What is the value of pKb for ammonia? (b) What is the pH of the

  1. chemistry

    when ammonia is added to Zn(NO3)2 solution, a white precipitate forms, which dissolves on the addition of excess ammonia. But when ammonia is added to a mixture of Zn(NO3)2 and NH4NO3, no precipitate forms at any time. Suggest an

  2. Chemistry

    When dilute nitric acid was added to a solution of one of the following chemicals, a gas was evolved. This gas turned a drop of limewater, Ca(OH)2, cloudy, due to the formation of a white precipitate. The chemical was.... a. the

  3. chemistry

    A student placed 11.5 of glucose () in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100.- mark on the neck of the flask was reached. The flask was then

  4. chemistry

    Would the following procedural errors result in an incorrectly high or low calculated percent NaOCl in commercial bleach solution? A student failed to allow the volumetric pipet to drain completely when transferring the diluted

  1. Chemistry

    A student placed 12.0g of glucose (C6H1206) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100.-ml mark on the neck of the flask was reached. The

  2. Chemistry

    A student placed 17.0 g of glucose (C_6H_{12}O_6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100 mL mark on the neck of the flask was reached. The

  3. Please Help Fast

    A student placed 10.5g of glucose (C6H12O6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the 100.- mL mark on the neck of the flask was reached. The

  4. chemistry help

    What mass of ammonium chloride must be added to a 0.500 L solution of 0.250 M ammonia to make a buffer with a pH of 9.26? Kb (NH3) = 1.8 × 10–5?

You can view more similar questions or ask a new question.