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

To carry out a titration between a strong acid and a weak alkali, to eventually find the unknown concentration of sulphuric acid. However, the sodium carbonate (weak alkali) is solid, and you need two liquids to carry out a titration.

Extracts from this document...

Introduction

Finding out How Much Acid There is in a Solution Planning: - Introduction: - During the extraction of a metal from its ore, sulphur dioxide is often produced. This is converted to sulphuric (VI) acid and is sold as a useful by-product. I am going to be given a sample of sulphuric acid which is thought to have a concentration between 0.05 and 0.15 mol dm3. I have to find out its accurate concentration by carrying out a titration between sulphuric acid and sodium carbonate. It is an acid-alkali titration. A titration is the "determination of material concentration by the successive addition of measured amounts of standard reagents to a known volume or weight of solution until a desired end point is reached." Acids and alkalis are classified as "strong" or "weak" depending on the extent to which they form ions when dissolved in water. Sulphuric acid is a strong acid which means it is completely in the form of ions in dilute solution. Sodium carbonate is a weak alkali, which means the process is only partially complete. Methyl orange is the best indicator to use to find the end point of a titration between a strong acid and a weak alkali. Na2CO3 (aq) + H2SO4 (aq) Na2SO4 (aq) + CO2 (g) One mole of sodium carbonate is needed to neutralise one mole of sulphuric acid. It has a 1:1 ratio. Aim: - To carry out a titration between a strong acid and a weak alkali, to eventually find the unknown concentration of sulphuric acid. However, the sodium carbonate (weak alkali) is solid, and you need two liquids to carry out a titration. This means I will make the sodium carbonate into a solution in order to carry out the titration, by dissolving it in distilled water. The concentration of the sodium carbonate solution is 0.1 mol dm-3 Apparatus: - * Spatula (to measure out the sodium carbonate) ...read more.

Middle

This helps make the actual titration much faster and more accurate and reliable, as I will know the exact amount of acid to use, and I will roughly know when to slow down the addition of sulphuric acid to the sodium carbonate solution to a drop. I am using the best indicator for reactions between strong acids and weak alkalis. This means the end point of my titration will be determined accurately, so that I can correctly work out the concentration of sulphuric acid. In devising my plan, I checked against another plan from the "student support coursework guidance" sheet, and my plan seems reasonable. I think it can be relied upon to produce accurate and reliable results. Implementing: - TITRATION READINGS ROUGH 1 2 3 4 5 AVERAGE TITRE Final 29.6 27.6 28.5 28.6 29 28.4 28.42 Initial 0 0 0 0 0 0 0 Amount of H2SO4 used (ml) 29.6 27.6 28.5 28.6 29 28.4 28.42 Analysing Evidence and Drawing Conclusions: - Moles = concentration x (volume/1000) What is the concentration of 250cm3 solution containing 2.65g of Na2CO3? Na2CO3 (aq) + H2SO4 (aq) Na2SO4 (aq) + CO2 (g) 1 mole of Na2CO3 neutralises 1 mole of H2SO4 1:1 Number of moles of sodium carbonate = Mass/RFM =2.65g/106 =0.025 Concentration of sodium carbonate = moles x (1000/volume) =0.025 x (1000/250cm3) =0.1M Number of moles of sodium carbonate = concentration x (volume/1000) = 0.1 x (25/1000) = 0.0025 What is the concentration of 28.43ml of H2SO4? Na2CO3 (aq) + H2SO4 (aq) Na2SO4 (aq) + CO2 (g) 1 mole of Na2CO3 neutralises 1 mole of H2SO4 1:1 I have already worked out the number of moles of sodium carbonate, and as there is a 1:1 ratio, sulphuric acid is the same number of moles. Therefore, 0.0025 moles of sulphuric acid = concentration x (25/1000) Concentration of sulphuric acid = 0.0025 x (1000/25) = 0.1M Conclusion: I can see from my results that the sodium carbonate solution and the sulphuric acid solution have the same concentration of 0.1M. ...read more.

Conclusion

This will ensure that my sodium carbonate solution is accurate, and will mean I can work out the concentration of sulphuric acid more accurately. However, this may be unnecessary for what I am doing, as the percentage error for the balance wasn't that high, and did not have a very significant impact on my results. A titration using a pH meter could be carried out, which is much more accurate, as the pH meter electrode is inserted in the solution, and I can read the pH and handle the burette with ease. It is better than a colour change because human error is not involved; it is all electronic and therefore more accurate. It will then be easier to work out the concentration of the sulphuric acid solution. I think I should have used a different bottle of methyl orange because the one I used was difficult to squeeze and the drops came out different sizes, leading to inaccuracies in the concentration of the green colour of my sodium carbonate solution. More acid is required to make a darker green turn clear, then a light green, so this is an extremely important change to improve my procedure. Other than that, I think I had an extremely accurate and reliable procedure as I kept the temperature constant, therefore liquid expansion was prevented, and volume readings contained no errors. Fixed errors in the measuring devices were cancelled out by using the same instruments. Some of my glassware was extremely accurate, such as the volumetric flask, and I was able to make an accurate sodium carbonate solution. The pipette was also extremely accurate as it delivered exactly 25cm3 of sodium carbonate solution into the conical flask. I also washed out all my glassware to ensure there was no contamination, and so that all the sodium carbonate was transferred properly to get an accurate solution concentration. I also shook my sodium carbonate solution after the final dilution to mix it thoroughly. I took adequate safety precautions to ensure my procedure was safe as well as accurate and reliable. Aisha Hussain Page 1 28/04/2007 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous 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 GCSE Aqueous Chemistry essays

  1. Marked by a teacher

    Back Titration Lab Report. In my experiment, I hoped to find the amount of ...

    4 star(s)

    1000 =4.15 x 10-3 moles of Sodium Hydroxide. Moles of acid = 4.15 x 10-3 moles Molarity of HCl = Moles x 1000 Volume = 4.15 x 10-3 x 1000 25 � 0.1 = 0.166 mol dm-3 Moles of HCl in 250 cm3 solution = Morality x Average volume 1000 = 0.166 x (250 x � 0.2 cm3)

  2.  Standardization of sulphuric acid.

    4 Preparation of 25 ml of sulphuric acid a. Sulphuric acid was contained in the beaker. b. The pipette filler was used to pull up the sulphuric acid through the pipette to the graduated mark. c. The 25 ml of solution was released in the conical flask.

  1. How much Iron (II) in 100 grams of Spinach Oleracea?

    Procedural Errors It was difficult to judge the end point of the reaction even though a dramatic colour change took place. This was because a single extra drop of Potassium Manganate (VII) (aq) turned the solution a deeper shade of purple.

  2. To determine the concentration of a sodium carbonate solution

    Remove the filter funnel and using a dropping pipette add enough water to bring the bottom of the meniscus up to the mark. 4) Invert the flask several times to help the contents mix the contents (e.g. label it Dilute Hydrochloric acid), If someone is doing a similar experiment label it with your name.

  1. The Use of Volumetric Flask, Burette and Pipette in Determining the Concentration of NaOH ...

    (Note: Burette and pipette must be rinsed 2-3 times with 5 cm� of solution to be used. Every time filling up burette using a funnel, the funnel is held to avoid the breakage to the burette and spill of fluid due to the displacement of air.

  2. Finding the concentration of sodium carbonate.

    = 0.08 mol.dm-3 (2 d.p.) Evaluating Evidence and procedures. The final titration was an anomalous result - 34.30cm3. A result much larger than the average of 32.23cm3 (3.07cm3 larger). All the other results (apart from the first which is only a rough titration so that later ones can be more accurate)

  1. In order to find out the exact concentration of sulphuric acid, I will have ...

    However once there is an excess of acid present, the curve should gradually even out. Furthermore at the very beginning of the curve, pH will decrease quite rapidly once the acid is added, but soon after that the gradient should decrease.

  2. Experiment to determine the concentration of sulphuric acid

    The number is recorded. The burette is held by a clamp and stand A white tile is put under the burette and the conical flask is placed on the white tile. The tip of the burette should be in the conical flask but not touching the liquid.

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