chemistry

An impure sample of barium hydroxide of mass 1.6524 g was allowed to react with 100 cm3 of 0.200 mol dm-3hydrochloric acid. When the excess acid was titrated against sodium hydroxide, 10.9 cm3 of sodium hydroxide solution was required. 25.0 cm3 of the sodium hydroxide required 28.5 cm3 of the hydrochloric acid in a separate titration. Calculate the percentage purity of the sample of barium hydroxide.

  1. 👍
  2. 👎
  3. 👁
  1. The idea here is the Ba(OH)2 is neutralized by the HCl BUT more acid is added than is necessary. So you must determine how much of an excess HCl was added. You do that by titrating with NaOH. However, the strength of the NaOH is not given to you. In the separate titration of NaOH you determine the molarity (mols/dm3) of the NaOH.

    In the separate titration with NaOH, we have 28.5 cc of the 0.200 M HCl solution reacting with 25.0 cc of the NaOH. Determine the mols/dm3 = M) of the NaOH.
    ...................NaOH + HCl ==> NaCl + H2O
    millimols HCl = mL x M = 28.5 x 0.2 = 5.7
    millimols NaOH must be 5.7 since the equation shows 1 mol HCl = 1 mol NaOH.
    Then M NaOH = millimols/mL = 5.7/25.0 = 0.228 M.

    .................Ba(OH)2 + 2HCl ==> BaCl2 + 2H2O
    millimols HCl added initially = mL x M = 100 mL x 0.200 M = 20.0
    Excess HCl added = millimols NaOH added = 10.9 mL x 0.228 M = 2.485 millimols HCl excess. So how much Ba(OH)2 was present.
    Total HCl added = 20.0 millimols.
    - excess HCl ......= 2.485
    --------------------------------------
    20.0 - 2.485 = 17.5 millimols HCl.
    Millimols Ba(OH)2 is 17.5 x (1 mol Ba(OH)2/2 mol HCl) = 8.76 mmols = 0.00876mols.
    Convert to grams Ba(OH)2. g Ba(OH)2 = mols Ba(OH)2 x M Ba(OH)2 = ?
    Then % Ba(OH)2 = (grams Ba(OH)2/1.6524)*100 = ?
    Check my work, especially the arithmetic. Post your work if you get stuck.

    1. 👍
    2. 👎
    👤
    DrBob222

Respond to this Question

First Name

Your Response

Similar Questions

  1. Science

    Barium sulfate, BaSO4, is a white crystalline solid that is insoluble in water. It is used by doctors to diagnose problems with the digestive system. Barium hydroxide, Ba(OH)2, is also a white crystalline solid and is used in

  2. Chemistry

    A 1.00 g sample of limestone is allowed to react with 100 cm^3 of 0.200 mol/dm^3 HCl. The excess acid required 24.8 cm^3 of 0.100 mol/dm^3 NaOH solution. Calculate the percentage of calcium carbonate in the limestone

  3. chemistry(Urgent Please help)

    A student is asked to standardize a solution of barium hydroxide. He weighs out 0.945 g potassium hydrogen phthalate (KHC8H4O4, treat this as a monoprotic acid). It requires 33.9 mL of barium hydroxide to reach the endpoint. A.

  4. ap chemistry

    what mass of barium sulfate can be produced when 100 ml 0.100 M of solution of barium chloride is mixed with 100.0 ml of a 0.100 M solution of Iron (III) sulfate

  1. Chemistry

    1.2048g sample of impure Na2CO3 is dissolved and allowed to react with a solution of CaCl2 resulting CaCO3 after precipitation, filtaration and drying was found to weight 1.0362g. calculate the percentage purity of Na2CO3

  2. Chemistry

    Consider the reaction: 3Ba(s)+N2(g)--->Ba3N2(s) 1)How many moles of barium metal react to produce 0.190 mol of barium nitride? 2)How many moles of nitrogen gas react?

  3. chem

    What is the pH of a solution prepared by diluting 25.00mL of 0.020M barium hydroxide to a volume of 100.00mL?

  4. Chemistry

    A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) After 1.27 g of the impure metal was treated with 0.100 L of 0.768 M HCl, 0.0125 mol HCl remained.

  1. Analytical chemistry

    A 0.6334 gram of sample of impure mercury (II) oxide was dissolved in an unmeasured excess of potassium iodide. Reaction: HgO + 4I- + H2O ------→HgI42- + 2OH- Calculate the % HgO in the sample if titration of the liberated

  2. chemistry

    1. (Answer c)The hydroxide ion concentration in a 1.0 mol/L solution of acetic acid at 25°C is a.4.2 x 10^-3M b.2.4 x 10^-11M c.2.4 x 10^12M d.2.4 x 10^-3M e.1.8 x 10^-5M I did [OH-]=root(Kw/Ka) x [salt] [OH-]=root(1.00 x

  3. chemistry

    0.4324 g sample of a potassium hydroxide-lithium hydroxide mixture requires 28.28 ml of 0.3520 M HCl for its titration to the equivalence point. What is the mass percent lithium hydroxide in this mixture?

  4. chemistry

    Hi, I need help figuring out this question. An impure sample of barium hydroxide, Ba(OH)2 (aq), has a mass of 0.540 g. It is dissolved in water and then treated with excess sulfuric acid, H2SO4(aq). This results in the formation

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