• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Design - Investigate the effect of one factor on the experimentally determined pKa of a weak acid

Extracts from this document...


HL Chemistry Design Prac Investigate the effect of one factor on the experimentally determined pKa of a weak acid. _______________________________________________________ Research question: How will changing the concentration of the reaction ethanoic acid affect the experimentally determined pKa value of ethanoic acid with hydroxide? Background Research: In chemistry, the acid dissociation constant, Ka, is known as the equilibrium constant for the reaction between weak acid and conjugate base, both in aqueous state. A + B <=> C + D To calculate the value of Ka in the reaction above, the concentration of C and D over A and B is to be calculated. ...read more.


However, it is preferable to measure in Ka value instead of pKa value, because adding excess amount of water will affect the pKa value but not Ka value. Defining Independent and Dependent Variables: Independent Concentration of OH- * 0.1M * 0.2M * 0.5M * 1M * 2M * 4M Dependent Concentration of ethanoic acid Controlling Variables: Table 1 - Variables and Method of control Type Variable Method of Control Controlled Amount of ethanoic acid Use 100ml measuring cylinder (�0.5ml) One person measuring the amount of propanoic acid to reduce the error in reading Amount of hydroxide Use 100ml measuring cylinder (�0.5ml) ...read more.


* GLX * pH meter Method: 1. Measure 20ml of 1M of ethanoic acid and 20ml of 0.1M of hydroxide and place them into a beaker. 2. Use GLX and pH meter to find the pH of the solution. 3. Calculate the Ka from the pH 4. Calculate the pKa from the Ka by taking negative log of Ka. 5. Repeat step 1 to 4, four more times to minimise the uncertainties 6. Repeat step 1 to 5, with different concentration of OH- Results: Table 2 - 0.1M of OH- Trials pH Ka pKa 1 2 3 4 5 Table 3 - 0.2M of OH- Trials pH Ka pKa 1 2 3 4 5 Table 4 - 0. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Chemistry essays

  1. Acids/Bases Design Lab. How does a change in the pH value of a solution ...

    and reacted with the solution of hydrochloric acid, since it oxidizes and forms a protective layer of zinc oxide (Gagnon, n.d.). This could add extra mass to what is believed to be solely zinc metal that is being massed on the electronic milligram balance.

  2. Chemistry extended essay - investigate the effect of 2-bromo-2-methyl propane concentration and temperature of ...

    2- Swirl the mixture and after one or two seconds immediately pour the combined solutions back into an Erlenmeyer flask #4 to minimize the errors in the results. 3- The color of the mixed solutions is blue, so continue swirling the solution in Erlenmeyer flask #4 till the instant color

  1. IB chemistry revision notes

    o They are the salt makers. o As we go down the group, atomic, ionic and covalent radii increase. Ionisation energies for this group are the second highest in the periodic table. o As we go down the group, the reactivity of the halogen decreases, but the halide's increases.

  2. A Comparison of Strong and Weak Acids and Bases

    For example, there are 1.00M , 0.10M and 0.01M of HCl(aq). Table 1.8: The pH values obtained by the pH probe for CH3COOH(aq), HCl(aq), H2O(l), NH3(aq) and NaOH(aq). Solutions Concentration of solution / mol dm-3 pH value of the solutions / pH (�0.01) CH3COOH(aq) 1.00 2.31 HCl(aq) 0.01 2.08 HCl(aq)

  1. IB Chemistry Lab Design - compare the effect of temperature on the concentrations of ...

    Transfer this to a 500 ml beaker. 1. Dissolve the solids in approximately 400 ml of distilled water. Stir using the glass rod, to aid in dissolving. Add the 60 ml of 3.00 M sulphuric acid to the solution at this point.

  2. Measuring the fatty acid percentage of the reused sunflower oil after numerous times of ...

    As to get clearer and more trustful results from this kind of experiments, the investigation should be repeated and the trial number trustful ones.per experiment should increase. By only this way the results may come near to the hundred percent Word Count: 4.464: including tables excluding calculations 4.171: excluding both

  1. Determining Ka by the half-titration of a weak acid

    = 0±0.2% So PH= 14±0.2% Thus with these results we can plot this: Volume of NaOH (0.2%) PH of solution (±0.2) 0 2.38 45 14 48 14 50 14 We know that at volume of NaOH of 45 and 48, the PH will still be 14 as it’s in excess

  2. The chemistry of atmospheric and water pollution.

    and the concentration determined is expressed as mg/L of CaCO3. Levels of calcium and magnesium ions can be determined using AAS. Can qualitatively determine if water is hard by adding soap to it. Shake and if soap does not lather then the water is hard.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work