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Determination of acid concentration in gastric juice

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Introduction

Determination Of The Concentration Of Acid In Gastric Juice Introduction: In this experiment, I will be able to carry out a technique known as titration. The experimental titration is used to find out how accurately how much a chemical substance is dissolved in a given volume of a solution, that is the concentration of the solution. The aim of this particular experiment is to revise the use of pipettes and burettes and titrations by the determination of the concentration of hydrochloric acid in an unknown solution and also reinforce the concept of molarity hence I will be using the method titration. This particular method is suitable for our aim because it will allow us to obtain results which enables us to determine the molarity of a solution of sodium hydroxide against our two separate standards. The equation I will be looking at is: NaOH(aq) + HCl(aq) � NaCl(aq) + H2O(l) Acid Base Salt Water The reaction is an acid-base reaction which involves the transfer of protons. Acid-base reactions are also known as neutralisation reacrions. The compound formed by the cation of the base and the anion of the salt. When using the indicator, phenolphthalein, the colour will change to light pink. ...read more.

Middle

* Note down your results. * Repeat the experiment 3 times * In order to get concordant results, results should be within +0.01 of each other. * Repeat the experiment using gastric juice as your standard instead of HCl. Results Results showing the titration of sodium hydroxide solution with 25cm3 0.01mol dm-3 HCl: Initial burette reading(cm3) Final burette reading (cm3) Volume Used(cm3) Rough titration (HCl) 0.00 cm3 25.7cm3 25.7cm3 First Accurate Titration 0.00 cm3 25.6cm3 25.6cm3 Second Accurate Titration 0.00 cm3 25.5cm3 25.5cm3 Third accurate Titration (If needed) N/A N/A N/A Average Volume of Sodium Hydroxide solution used= 25.60cm3 Number of moles of NaOH present in this volume = 2.56 x 10cm-4 25.6/1000 =25.6/1000 Therefore: molar concentration of NaOH= 0.01 Results showing the titration of sodium hydroxide solution with 25cm3 0.01mol dm-3 Gastric Juice: Initial burette reading(cm3) Final burette reading (cm3) Volume Used(cm3) Rough titration (Gastric Juice) 0.00 cm3 30.7 cm3 30.7 cm3 First Accurate Titration 0.00 cm3 31.5 cm3 31.5 cm3 Second Accurate Titration 0.00 cm3 30.8 cm3 30.8 cm3 Third accurate Titration (If needed) 18.1 cm3 49.0 cm3 30.9 cm3 Average Volume of Sodium Hydroxide solution used= 30.8cm3 Number of moles of NaOH present in this volume: =3.08x10-4 30.8/1000 =30.8 x 10-4 Therefore number of moles of HCl in 25cm3 of gastric Juice= 3.08 x ...read more.

Conclusion

In order to make this more accurate, I could use longer and thinner burettes which will allow me to obtain a much more accurate reading. Also the pH of gastric juice differed. In order to overcome this, we could measure the gastric juice beforehand instead of after the experiment. We could also measure it before each titration. In my experiment, I tried to minimise error wherever I could and also make my experiment reliable. I tried to make sure, in order to minimise any possible additional errors to wash out all of my equipment by washing it with distilled water to avoid any contamination. All of my experiment I would say is reliable as they can be repeated and tested again. Conclusion In conclusion, my results were accurate and reliable to the best of my ability; however with using more precise equipment and having a longer to do it may have increased the accuracy. Also with aids of a colour wheel in order to obtain the same shade of pink may help. The aims of this experiment were met was we managed to work of the molarity of our two substances by using the titration method. Overall I think that the titration experiments for both the HCL and the gastric juice were successful. Referencing http://www.bsieducation.org/Education/14-19/topic-areas/applied-science/images/titration-equipment.jpg ?? ?? ?? ?? 1 ...read more.

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