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

The Relative Formula Mass of an Unknown Acid.

Extracts from this document...

Introduction

The Relative Formula Mass of an Unknown Acid Introduction I have been provided with a solution of unknown monobasic acid. By titration with a standard solution of sodium hydroxide I am to calculate its molarity and hence the relative formula mass of this unknown acid. (We can assume the concentration of the sodium hydroxide is 0.1M) Procedure 1. Using the funnel, rinse the burette with the acid solution and fill it accurately with the same solution until the 0cm3 mark (Do not forget to rinse and fill the tip first though). 2. Using the pipette filler, rinse the pipette with some of the sodium hydroxide solution and carefully transfer 25.0cm3 of the solution to a clean 250cm3 conical flask (Remembering to touch the bottom of the flask with the tip of the pipette for ten seconds to fully empty the pipette). ...read more.

Middle

8. Repeat steps 5,6 and 7 at least until there are three concurrent results. 9. Empty the burette and wash it carefully immediately after the titration, especially if it has a ground glass tap. Results Titration no. 1 2 3 4 5 Titre value 21.7cm3 21.2cm3 21.2cm3 21.3cm3 21.2cm3 To calculate the mean titration value I added together the last four results and divided by four. I opted to leave out the first result as this was my trial run and wasn't concurrent with the others. *MEAN TITRE ? (21.2 + 21.2 + 21.3 + 21.2) ? 4 = 21.23cm3 Analysis As we are told that the acid is monobasic the equation for the reaction can then be written as " HA + NaOH ? NaA + H2O " (Where HA is the unknown acid) Following on from the fact that the acid is monobasic, and therefore reacts with the sodium hydroxide on a one to one ratio, it is then possible to use the formula 'V1C1=V2C2' (V = volume in dm3 and C = conc. ...read more.

Conclusion

7.5g ? (21.23 ? 1000) = 0.159225g Now we can simply use the formula below: "Relative formula mass = Mass ? No. of moles" = (0.159225) ? (0.002505) = 63.56g From the acids given as possibilities it is clear that the unknown acid is "HNO3" which has a relative molecular mass of 63g. This is a difference of 0.88% from my result (calculated as shown below). [ (63 ? 63.56) ? 100 = 99.12% ] This percentage difference may be due to slight inaccuracies of the equipment used for the experiment. Below I have calculated the maximum percentage error for each piece of apparatus and also the total percentage error. * 250cm3 volumetric flask ? 0.5cm3 ? (0.5 ? 250) ? 100 = 0.2? * 25cm3 pipette ? 0.05cm3 ? (0.05 ? 25) ? 100 = 0.2? * Burette ? 0.15cm3 ? (0.15 ? 21.23) ? 100 = 0.71? TOTAL MAXIMUM PERCENTAGE ERROR ? 1.11% This helps explain the slight differences in answers. ...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. The Formula of Succinic Acid

    and adding more distilled water if necessary until all the solute has dissolved. On completing that I will wash a 250cm3 volumetric flask out with distilled water. Then I need to transfer all the solution into the volumetric flask. I will do this using the aid of a funnel (which will have also been washed in distilled water).

  2. Determine the relative formula mass and the molecular formula of succinic acid

    * Rinse the inside edges of the conical flask with distilled water to wash all the NaOH into the bottom of the flask.

  1. Titrating Sodium hydroxide with an unknown molarity, against hydrochloric acid to find its' molarity.

    will affect where the meniscus is and so what readings are obtained from the burette. Ensure that the tap on the burette is turned to the off position. 2. Using a weighing bottle, weigh out 1.33g of anhydrous sodium carbonate (making sure to zero the balances before placing the Na2CO3

  2. Explain how the enthalpy change of neutralisation can be used to determine the relative ...

    The ions react very easily to reform the acid and the water. At any one time, only about 1% of the ethanoic acid molecules have converted into ions. The rest remain as simple ethanoic acid molecules. Most organic acids are weak. Hydrogen fluoride (dissolving in water to produce hydrofluoric acid)

  1. 'The Molecular Formula of Succinic Acid'.

    To make sure I have all the acid I will wash the weighing bottle with distilled water and add it to the beaker, I will do this three times just to be certain I have all the acid. I will carry on stirring with a glass rod (which will have also been washed in distilled water before use)

  2. Identification of an Organic Unknown.

    Justification: Primary alcohols undergo oxidation when reacted with a mixture of potassium dichromate (VI). In the reaction the orange dichromate (VI) ions are reduced to green chromium (III) ions. Tertiary alcohols resist oxidation. I can test for a tertiary alcohol by adding sodium however I tested for a primary alcohols

  1. The aim of the experiment is to find the relative formula mass of an ...

    Some chemicals can pose a risk. In this case an alkali (sodium hydroxide) is corrosive chemical. In contact with skin it will cause burn and damage eyes. From the label of the unknown acid you can deduce that it is a toxic substance which is poisonous and can kill you.

  2. Identification of an organic unknown.

    (Ramsden, E. N; A-Level Chemistry, (Stanley Thornes Ltd. page 647) There are therefore a number of reagents that will react with and also oxidise aldehydes with ease but not ketones. One such reagent is Tollens' reagent. Another is warm Fehlings' solution that works on the same bases as Tollens' reagent but with different consequences.

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