• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14

Titration with a primary standard.

Extracts from this document...

Introduction

TITRATION WITH A PRIMARY STANDARD 1. Wear all the protective attire required and make sure that all the equipment is collected and is thoroughly cleaned with distilled water leaving it dirt free, so that the chemicals being used will not be contaminated during the experiment. 2. Determine the mass of the weighing boat and then weigh out 0.265g g of dry Na2CO3. Record actual mass used to nearest 0.01 g. Transfer the solid to a 250 ml Erlenmeyer flask, rinse the weigh paper (or weighing bottle) into the flask with a small amount of distilled water and dissolve the solid with 25 ml of distilled water. Using a stirring rod, stir the solid and water in the beaker to dissolve, adding more water is necessary. 3. Transfer carefully the solution to the 250cm3 volumetric flask (pouring the solution down the funnel to avoid spillage). Rinse the beaker three times to make sure all the solution goes into the volumetric flask, each time pouring the solution down the stirring rod to rinse it. 4. Carefully make up the solution to about 1cm of the mark on the neck of the flask using distilled water.Insert the stopper and shake to mix the contents. 5. Using a dropping pipette, add enough distilled water to bring the bottom of the meniscus on the mark. Now, mix it thoroughly, by turning the volumetric flask upside down twice, to ensure complete mixing 6. Clean and check the flow rate of the burette . Setting and Determination of the flow rate: Put a 25 ml graduated cylinder underneath the end of the tubing. Turn on the air pump, and collect a certain volume (e.g., 20 ml) of the titrant in the cylinder. Measure the required time (t). Calculate the flow rate (F) as follows: F= V(ml) / t (s) A flow rate of about 1-3 ml/min (0.0166-0.05 ml/sec) is appropriate Do not change the settings once you have measured the flow rate. ...read more.

Middle

Stop once the minimum is reached. Place the white tile under the flask to better observe any colour changes. 8. Start to add the NaOH solution drop by drop, swirling after each drop. 9. When a hint of pink appears, swirl the flask well. The colour may disappear. If it doesn't, the endpoint is reached. Record this volume. If the colour fades, proceed to step 10. 10. Add 1/2 drop to the flask. This is achieved by opening the stopcock until only part of a drop is hanging from the tip of the burette. Touch the tip to the inside of the flask. Rinse the drop into the flask with some distilled water and swirl well. Repeat if the solution is colourless. Once the endpoint is reached record your final volume. NOTE: If the colour of the solution is a strong bright pink, you have passed the endpoint and your final volume is not accurate. 11. Repeat steps 7-10 for the other two acid samples. Be sure your initial volume of NaOH is always over 30 ml before you start. (It need not be near 0 ml. as this wastes the solution) Flush the contents of the beaker down the drain with lots of water. Rinse the burette thoroughly with tap water (3 times) then 3 times with distilled water. Verify that the final rinse is neutral by placing a drop from the burette on red litmus paper. If it is still basic, the red litmus will turn blue. Making a solution from solid base. mol NaOH = MNaOHVNaOH g NaOH = mol NaOH x MolMass NaOH The mass of NaOH needed to make 500.0 mL of 0.2000 M NaOH g NaOH = (0.2000M NaOH x 0.5000 L) x 40.00 g NaOH/mol NaOH = 4.000 g NaOH Making a solution from a more concentrated base solution. Vinitial = (MfinalVfinal) Minitial The volume of 9.0 M NaOH needed to make 50.00 mL of 2.5 M NaOH VNaOH = (2.5 M NaOH x 0.05000 L) ...read more.

Conclusion

Solution Steps: 1. Write a balanced equation: 2NaOH + H2SO4 Na2SO4 + 2H2O 2. Determine the number of moles of the standard NaOH solution used: 3. Use the mole ratio from the balanced equation to convert moles of NaOH to moles of H2SO4: 4. .Use the volume of acid solution used to determine the molarity of the acid solution: 5. Notice that the 1dm3/1000cm3 and the 1000cm3/1dm3 will offset each other. One may shorten the problem by skipping these conversions EXPERIMENTAL ERROR: In order to calculate your experimental error for each of your reactions, use the equation below. The theoretical value is the heat of reaction, for your acid, per mole of water formed, shown in Table 1. The experimental value is the actual heat of reaction you determined in each of your experiments (per mole of water formed). To obtain %Error for a measurement, you need to know the Theoretical and Experimental values for your measurement, or set of calculations. Use this formula to obtain the %Error, which is always a positve (absolute) value. FURTHER STUDY: 1. Repeat procedure with the concentrations of H2SO4 and NaOH reduced 10 and 100 times. Study the effect of concentration on the pH change. 2. Plot the first derivative (dpH/dt) against time of all the previous experiments and locate the end point in each case. The end point in the first derivative curves are defined as the point at the maximum value. The first derivative curves can be obtained by graphing programs such as MicroCal Origin. SOURCES CONSULTED: * Rendle, Vokins and Davis, 1991. Experimental Chemistry, Second Edition. London: Arnold. * Ottewill and Walsh, March 1996. 'Electrochemical Cell' and 'How to use electrochemical cells' . Chemistry Review Vol:4 Num:4. * Atkins, 1990. Physical Chemistry, Fourth Edition. Oxford: OUP. * Fine and Beall. Chemistry for Engineers and Scientist.. USA: Saunders College Publishing. * Salter Advance Chemistry Course 1994. 'Redox', 'Redox reactions and electrode potentials' in 'Chemical Ideas'. Oxford : Heinemann Educational Jeffery, Bassett, Mendham, Denney: Vogel's Textbook of Quantitative Chemical Analysis, 5th e ...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

    Chem MC analysis. In which of the following cases may it obtain a complete ...

    5 star(s)

    The number of moles of HCl unreacted with NaOH :0.05-0.005 = 0.045mol ?The neutralization is not complete Some students may forget to divide the number of moles in 250cm3 of NaOH by 10.Consequently, they wrongly think that 0.05 mol of NaOH reacts with 0.05 mol HCl , and so the neutralization is complete.

  2. Standardization of NaOH and Analysis of Unknown Acid Sample.

    18.62mL (?0.02) 18.85mL (?0.02) Observed variances: Flask 1 was pinker than both 2 & 3. 2 & 3 were roughly equal in tint. Calculations: Trial I: .02728 L NaOH x 0.0937 M NaOH = .00255 mol NaOH or H(a) 0.529g H(a)

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

    Add distilled water to the volumetric flask until it is about 1 cm below the graduation mark 3) Clean a strip of Iron (s) using emery paper, rinse it in distilled water (l) and dry it using a paper towel.

  2. Planning of Titration

    because they could be mistaken for beverages or foods. At the end of the experiments, empty the beakers and wash them. Place the containers of the remaining substances, which you want to preserve in suitable places. Sulphuric acid is normally very corrosive and irritant when over 1.5 M but in this titration there is only a concentration between 0.05

  1. In this experiment I am finding out how much sulphuric acid is present in ...

    The meniscus may be seen more clearly if a small white card with a rectangular black patch is held behind the meniscus. Raise or lower the card until the bottom of the meniscus is clearly outlined.

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

    Now pour some sulphuric acid into the burette and make sure that the meniscus is as close to 0 as possible. 17. Now add 3 drops of orange methyl indicator and than add approximately 5cm3 of sulphuric acid. Now shake the contents of the beaker until you notice a faint colour change.

  1. Titration I will neutralize the sulphuric acid with a base, which will be Sodium ...

    I must calculate the mass of Sodium Carbonate used in the solution... Mass used 2.65 grams = =0.025 mols in 250ml Mass of Sodium Carbonate 106 grams To convert this to 1 litre I must multiply by 4 0.025 X 4 = 0.1 mols in a litre I will use

  2. To find the accurate concentration of sulphuric acid, by making up a standard solution, ...

    Pour the solution down the glass rod and into the funnel. This washes out the atoms and ions present on the glass rod. No drops should be lost, to guarantee accuracy. 9 Wash out the beaker, glass rod and the funnel, with the distilled water to make sure every bit of the solid is completely transferred into the volumetric flask.

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