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

Aim: To determine the concentration of chloride ions in sea water by titration with silver nitrate solution of known concentration.

Extracts from this document...


CHEMISTRY INVESTIGATION: VOLUMETRIC ANALYSIS Aim: To determine the concentration of chloride ions in sea water by titration with silver nitrate solution of known concentration. Hypothesis: To determine the concentration of chloride ions, sea water will be titrated with silver nitrate solution of known concentration. Silver ions form insoluble white silver chloride precipitation when added to a solution containing chloride ions: Ag+(aq) + Cl-(aq) � AgCl(s) Potassium chromate (VI) can be used to indicate the end-point of the titration, the point at which all the chloride ions have been precipitated. Silver ions combine with chromate (VI) ions to form a red precipitate of silver chromate (VI): 2Ag+(aq) + CrO42-(aq) � Ag2CrO4 (s) However, no silver chromate (VI) is precipitated until all the chloride ions have been removed. Therefore, the instant a permanent red tinge appears in the solution that does not vanish with vigourous swirling, the addition of silver nitrate solution should be stopped as the end-point of the titration has been achieved. It should be noted that silver nitrate is expensive, and is normally used in fairly low concentration. Thus, in this titration, only 0.05 mol dm-3 AgNO3(aq) is used. To obtain sensible results, it is necessary to dilute the sea water to give a concentration of chloride ions comparable to that of the silver nitrate. Apparatus: 1) 3 100cm3 beakers 2) 250 cm3 conical flask 3) (50.00�0.05)cm3 burette 4) Retort stand with clamp 5) Filter funnel 6) (10.00�0.05)cm3 pipette 7) (25.00�0.06)cm3 pipette 8) Pipette filler 9) (250.0�0.1)cm3 volumetric flask 10) Safety glasses 11) ...read more.


16) Wash the conical flask with plenty of distilled water. 17) Repeat 13, 14 and 15. Top up the burette if necessary (Step 10). 18) Repeat titration to collect another set of readings. However, this time stop before the end point recorded in 15 and add drops of F1 until the solution in conical flask changes colour. 19) Record the final burette reading. 20) Collect third reading by repeating 16, 17, 18 and 19. Safety: 1) Safety goggles have to be worn at all times to prevent chemicals used in the lab from coming into contact with the eyes when touch the face with our hands. 2) Wash hands after handling the chemicals to prevent irritation of the skin. Silver nitrate solution can leave a yellow stain on hands, clothes, papers. 3) Hair has to be tied up and away from the face to avoid hair falling into the chemicals. 4) Handle all apparatus carefully so as to avoid breakage. In the case, of a broken apparatus, report to the lab teacher so that the area can be cleared. 5) Ensure that you workspace is clear and uncluttered so that in the case of spillage, papers, etc will not be stained yellow and the spill can be cleared quickly. 6) Take care when fitting the pipette filler onto the pipette. Fit gently to avoid breaking the mouth of the pipette. Precautions: 1) Wash all the apparatus with distilled water to remove impurities that will result in inaccurate readings. ...read more.


Thus, only 2 readings were used to calculate the average. If time allowed, more readings could be taken and the average would reduce random error. After the initial rough titration, nearing the endpoint, silver nitrate was added drop by drop. A single drop resulted in the final colouration of the solution in the conical flask to be orange. However, the ideal endpoint is when there is a light orange solution. The persistant over-shooting of the endpoint can be a source of systematic error. 4) Since we know the concentration of chloride ions in sea water, the salinity of sea water per cubic decimetre can be calculated. Salinity of salt (NaCl) = 0.4625 � (22.99 + 35.45) = 27. 03gdm-3 5) This method of titration can be used to find the concentration of bromide ions in a solution as well. Ag+(aq) + Br-(aq) � AgBr(s) When all of the bromide ions has reacted to form silver bromide, a pale yellow salt that is insoluble, the addition of more Ag+ ions will react with the CrO42- ions. The indicator is still potassium chromate. However, if the solution contains both chloride and bromide ions in significant amounts, this titration method will not be accurate to find the concentration of either ions. 6) Residue containing silver ions can be save for later recovery of silver metal. The solution remaining in the burette can be reacted with any metal that is of a higher reactivity then silver such as copper or zinc. Silver will be displaced. The metal will form an aqueous solution. Thus, it is possible to obtain silver. ...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. Acid Base Titration Lab Report. The purpose of this experiment is to determine ...

    Reading the upper meniscus could increase the chance of having a higher reading than the actual reading. Always read the lower meniscus. It gives an exact eye level figure of the burette. Repeated experiments could also help in reducing this error. This is both a random and systematic error. 3.

  2. Investigate the rate of reaction of luminol in various factors. The objective was to ...

    order for the reaction, which means the effect of doubling the concentration would be quadruple. Evaluation This method provided reliable results, but there are also some errors in it. I have done the following things to avoid as much errors as possible.

  1. Testing for halide ions. The objective of the experiment was: ...

    Silver nitrate+ chlorine ion 2AgCl(s) + NH3 (aq) � Ag2(NH3)+(aq) + 2Cl-(aq) * Potassium bromide + ammonia? Silver nitrate+ bromide ion 2AgBr(s) + NH3 (aq) � Br2(NH3)+(aq) + 2Cl-(aq) * Potassium iodide + ammonia? Silver nitrate+ iodide ion 2AgCl(s) + NH3 (aq) � Ag2(NH3)+(aq) + 2Cl-(aq) * Potassium A15 + ammonia?

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

    The water was then decanted from the 500cm3 beaker into a waste beaker. 13. The beaker, labeled CRT1, containing the recently rinsed zinc metal strip that reacted with the hydrochloric acid solution for one minute, was then placed on a hot plate set to low heat, and allowed to dry off for 5 minutes.

  1. Limiting Reagent Lab. Purpose To ...

    An example of such substance is KNO3Pb(NO3)2 nitric acid (), which is insoluble to but soluble to. When HNO3Pb(NO3)2KNO3 nitric acid is added to solid and left over (which can be gained KNO3Pb(NO3)2 by boiling the filtrate) only will remain solid; therefore, it can be Pb(NO3)2 filtered to measure the mass.

  2. Percentage of Water In Popcorn

    Figure 1 - Setup Diagram Table 1 - Percentage of Water in Popcorn Beta, Gamma, and Delta Brand of kernels Trial 1 Trial 2 Trial 3 Average Beta 11.1% 11.3% 10.9% 11.1% Gamma 16.7% 15.7% 14.8% 15.7% Delta 19.4% 17.0% 19.0% 18.5% Table 2 - Percent Error Brand of kernels

  1. The purpose of this Titration Analysis of ASA experiment was to use titration analysis ...

    My end result from this experiment suggested that there is 11.08% more ASA in a standard pain-relief tablet than the accepted value on the label, though my end result maybe miles off, but I am here to evaluate my experimental process and what could have caused such a great difference.

  2. Research into the production of Nitrate Fertillisers.

    The ammonium fraction is taken up by roots or gradually converted to nitrate by soil microorganisms. Many vegetable growers prefer an immediately available nitrate source of plant nutrition and use ammonium nitrate. It is popular for pasture and hay fertilization since it is less susceptible to volatilization losses than urea-based fertilizers when left on the soil surface.

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