chemistry

In assessing 20.0ml of NaOH 0.175M , calculate how many ml of 0.200M HCl must be added to obtain a pH of 12.55

  1. 👍
  2. 👎
  3. 👁
  1. millimols NaOH = mL*M = 20*0.175 = 3.5
    If pH = 12.55, then pOH = 1.45 and (OH^-) = 0.03548 M so mmols at the end will be 0.03548*(20+xmL) where x mL is the volume of the 0.2M HCl added.

    .....OH^- + H^+ ==> H2O
    I...3.5.....0
    add.......0.2x..........
    C...-x...-0.2x.........s
    E.0.03548*(20+x)
    So we have mmols base-mmols acid = mmols base left over/total mL

    3.5 - 0.2x = 0.03548(20+x) where is the mL of the 0.2 M HCl added.
    Solve for x. The answer is close to 12 mL. You can check it this way.
    You have 0.175 x 20 = mmols NaOH initially.
    You add the value of mL HCl x 0.2 = mmols HCl added.
    Subtract to find mmols NaOH left.
    Then (OH^-) = mmols/total mL and convert to pH. I worked through it and it gives me 12.55 for pH. (pOH = 1.45)

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    Describe how you would make 500.0mL of a 0.200M NaOH solution from a 15.0 stock NaOH conentration

  2. chemistry

    Consider the reaction HCl + NaOH ->NaCl + H2O Given: HCl Solution: 22 degrees celsius NaOH Solution: 22 degrees celsius Final Temperature: 26.1 degrees celsius A. Calculate the amount of heat evolved when 15 mL of 1.0 M HCl was

  3. chemistry

    When 50.0mL of 1.20 M of HCl (aq)is combined with 50.0mL of 1.30 M of NaOH (aq) in a coffee-cup calorimeter, the temperature of the solution increases by 8.01 Degrees C. What is the change in enthalpy for this balanced reaction?

  4. chemistry

    A 5.309 g antacid tablet, with CaCO3 as the active ingredient, was mixed was 30.0 mL of 0.831 M HCl. After the reaction occurred, it took 15.3 mL of 0.7034 M NaOH to neutralize the excess acid. a) How much HCl (in mL) of was

  1. Chem

    How much water must be added to 500.mL of .200M HCL to produce a .150M solution? (.500mL x .200M)/.150M = .667mL Correct? A chemistry student needs 125mL f .150M NaOH solution for her experiment, but the only solution avail. is

  2. Chemistry

    Determine how many mL of solution A (acetic acid-indicator solution) must be added to solution B (sodium acetate-indicator solution) to obtain a buffer solution that is equimolar in acetate and acetic acid. Solution A: 10.0 mL

  3. chemistry

    What is the final volume of NaOH solution prepared from 250.0mL of 0.800M NaOH if you wanted the final concentration to be 0.200M

  4. chemistry

    If 15.0 mL of a 1.5M HCl solution at 22.5 degrees C is mixed with 25.0mL of a 1.5M NaOH solution at 21.5 degrees C that is in a calorimeter, and the final mixed solution temperature ends up at 28.5 degrees C, 1.)what is the

  1. CHEM

    Can you please check my work? I got -4.3KJ/mol If this is not right can you tell me what I am doing wrong? Thank you! Questions. 1.a. Use Hess's Law and the measured mean enthalpy changes for the NaOH-HCl and NH3-HCl reactions to

  2. Chemistry

    Hi, I posted yesterday with this lab question. "Calculate the molar amounts of NaOH used in the reaction with the HCl solution and with the HC2H3O2. I think I got the answer to that with the help that I received. I had 5 mL of

  3. chem101

    50.0ml of 0.10M HCL{aq} was added to 40.0ml of 0.10M NaOH{aq} and the mixture was stirred,then tested with a pH meter.What reading should be obtained for pH at 25.0degrees celcias?

  4. Chemistry

    How would you calculate the pH of the buffer if 1.0mL of 5.0M NaOH is added to 20.0mL of this buffer? Can someone please explain to me how to do B and C step by step so I could understand it clearly? :) Say, for example, that you

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