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Titration with HCl and NaOH

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Titration with HCl and NaOH Aim: Determine the concentration of a solution of sodium hydroxide solution using a standardised solution of hydrochloric acid. Health and safety: HCl/NaOH -corrosive-avoid spills, mop-up (gloves) -safety glasses -laboratory coat Pippete fillers- take care when using in case they snap when putting on the pipette Indicator -stains/poisonous Method Step 1. Wash out: i.) the pipette, with a little of the sodium hydroxide solution ii.) the burette, with a little of the hydrochloric acid solution iii.) the conical flask, with a little distilled water. Step 2. Fill the burette with the hydrochloric acid solution, running some of the solution through the tap, until the bottom of meniscus is just on the zero level. Ensure that there is no air bubbles trapped. Step 3. Using the pipette filler place 25cm3 of the sodium hydroxide solution in the clean conical flask. Step 4. Add 4 or 5 drops of methyl orange indicator to the contents of the flask. ...read more.


* Three results within 0.10 of each other Results For 25cm3 of NaOH the following results were obtained by titration using HCl. Rough Accurate Accurate Accurate Burette Reading end (cm3) 24.15 24.10 24.30 24.10 Burette Reading beginning (cm3) 0.00 0.00 0.00 0.00 Volume of HCl added (cm3) 24.15 24.10 24.30 24.10 Average Titre (cm3) 24.10 Calculations 1. Volume of HCl used = 24.10 cm-3 2. Concentration of HCl used = 0.107moldm-3 3. Volume of NaOH = 25.00 cm-3 4. Concentration on NaOH= ? moldm-3 or ? g moldm3 Calculations: i.) Moles of HCl = 1.08 x 24.1 = n = 0.00260 moles 1000 ii.)Moles of NaOH= 0.0026 moles NaOH + HCl NaCl + H2O Ratio of substances 1 : 1 Number of moles 0.0026: 0.0026 iii.) Concentration: n = qV 1000 0.0026= (q x 25)/ 1000 q = (1000 x 0.0026)/ 25 q = 0.104 moldm-3 iv.) Concentration in g moldm-3: n = m Mr m = 0.0026 x 40 = 41.6g Concentration on NaOH= 0.104 moldm-3 or 41.6 g moldm3 Compared to target value ...read more.


Total % error of apparatus = 1.03 % We can now compare the two values we had for: 1.) percentage off target value (1.23%) 2.) percentage error in apparatus (1.03%) If (1) < (2) that's as close as you can get with this apparatus If (1) > (2) then there are some other things that you need to do to improve your technique. This is human error. The suggested improvements in the accuracy of my experiment may reduce the margin for human error in my experiment. Use a more accurate burette which measures to 0.01 this will mean rounding to 2 d.p. is more accurate. It will mean (when estimating between the lines marked on the burette every tenth of a cm3) instead of being 0.01 (estimating hundredths) from the actual value we would be 0.001 (estimating thousandths) thus our reading would be more accurate when we round it up to hundredths. Repeat the titration more times- by doing this and averaging the closest few I would be more likely to find the precise volume of HCl required to neutralise the solution. ?? ?? ?? ?? Titration Prep 18/10/04 ...read more.

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