Determining the Concentration of Sulphuric Acid Essay Example for Free

Determining the Concentration of Sulphuric Acid EssayI am qualifying to plan an experiment to determine the accurate concentration of sulphuric acid. It is thought to contract the concentration between 0.05 and 0.15 moldm-3. I will be provided with a solid introduction which is anhydrous (powder) atomic number 11 carbonate (Na2CO3). To find the accurate concentration I will titrate the sulphuric acid against the sodium carbonate. The reaction following will take placeNa2CO3 (aq) + H2SO4 (aq) Na 2 SO4 (aq) + CO2 (g) + H2O(l)1Deciding the AmountsSulphuric acid has a concentration ab expose 0. 10 moldm-3 (half way between 0.05 and 0.15 moldm-3). I would like to commit 25cm3 of sulphuric acid. This is because, it is not a wasteful measuring stick and to a fault it would reduce percentage errors because this is quite a large amount to use. It would be an ideal value to use.Further more(prenominal), I will make to make up a standard resultant from the solid base that I have bee n provided with, which is sodium carbonate. I would again ideally like to use 25cm3 of the standard response per titer. This is because, the pipets have the reading of 25cm3, which means the pipette is readily, easy for this amount, therefore it is a sensible value.Consequently I will need to make up a standard declaration of concentration 0.10moldm-3. This is because of the stoichiometry. The equation shows that for e very(prenominal) one mole of sulphuric acid, there is one mole of sodium carbonate. Therefore, the concentration must be the same because the volumes atomic number 18 the same and the number of moles are the same. I estimated the concentration of sulphuric acid to be 0.10 moldm-3 because its halfway between the thought amount of 0.05 and 0.15 moldm-3, therefore the concentration of the standard solution must be the same.Deciding what Indicator to UseI need to use an indicator to see when the terminal full stop of the titration occurs, and they are utilize b etween acid and alkalis. I have decided on using 2-3 drops of methyl orange indicator fin my experiment per titre. This is because methyl orange indicator gives an accurate indication of the balance point using a strong acid (sulphuric acid) and a weak alkali (sodium carbonate). 2Making up my Standard SolutionAs I have mentioned before, I want my standard solution to have the concentration of 0.10 moldm-3. I have chosen my volumetric flaskful to be 250cm3. This is because these volumetric flasks are readily available. In addition, I am aiming to do approximately five titrations, therefore this amount would allow me to do five titrations and have some to spare.I now need to find out how much sodium carbonate (Na2CO3) is needed to make a standard solution of concentration 0.10 moldm-3.I need to use the equation list of moles = concentration (moldm-3) x volume(dm3)3n = c x vThe volume is 250cm3 so I need to divide this by constant of gravitation so that it veers into dm3.Number of moles = 0.10(moldm-3) x 0.25 (dm3)Number of moles = 0.025 molesTherefore, 0.025 moles id required for the standard solution, nevertheless, I now need to convert this into grams by using the equationNumber of moles = Mass (g) / Molar majority(gmol-1)4Mass (g) = Number of moles x Molar mass(gmol-1)Molar mass for Na2CO3 = (23 x 2) + 12 + (16 x 3) = 106gmol-1Mass (g) = 0.025 x 106 = 2.65gTherefore, 2.650g of sodium carbonate is required for my standard solution.My experimentThe apparatus I am sack to use are as follows* Burette* Conical flask* Volumetric flask* Rubber ball pipette filler* Distilled pee* Beakers* Filter funnel* Teat pipette* Tile* Sulphuric acid* Sodium Carbonate* Scales* Spatula* slowness nursing bottleful* Glass rod* Stand* Clamp* Methyl orange indicatorPlan of Experiment1. Prepare apparatus.2. Weigh a weighing bottle accurately. Using a spatula, transfer 2.650g of sodium carbonate to the weighing bottle and weigh again.3. Tip the contents of the weighing bottle i nto a clean 250cm3 beaker and reweigh the abandon weighing bottle to find the weight by difference. This way I can work out the actual weight of sodium carbonate that has been transferred.4. cater 50cm3 of distilled urine to the solid and stir using a glass rod until dissolved. Transfer this solution into a volumetric flask using a funnel. induce up the graduation mark with distilled water using a teat pipette to ensure you so not overshoot it. This is now the standard solution.5. install a stopper on the flask and invert it about 20 times to make sure all the solution is mixed.6. Using pipette filler, pipette 25.0cm3 of the solution into a clean conical flask.7. Clean the burette out with distilled water and indeed again with sulphuric acid. Attach the burette to the stand, and fill the burette using a funnel with sulphuric acid.8. Add methyl orange indicator to the conical flash only about 2-3 drops. Put the conical flask onto a white tile so the colour change is easy to see when titrating.9. Titrate the solution until you reach the end point (when the solution turns orange), and designate your results. I am going to use this as a rough titre.10. Repeat this to obtain concordant results, concordant meaning results that are similar commonly results which are in 0.1cm3 of each other.Risk AssessmentChemical NameForm UsedSafety StatementPrecautionsSulphuric Acid0.05-0.15 moldm-3Irritant take for granted eye protection and gloves. Wear a lab coat. If spilt on skin dry with a cloth and then wash with water. If spilt dry with cloth and then scrub using water. If it gets it contact with eyeball wash them with water thoroughly. 6Sodium CarbonateSolid and at0.10 moldm-3Irritant, but if dust gets in eyes its harmful.Wear sentry go goggles, gloves and also protective clothing. If in contact with eyes wash quickly with clean water. If spilt on skin wash intensely. If inhaled move to an study of fresh air. If spilt anywhere scoop as much as possible up. 5Methyl OrangeIndicator2-3 dropsIrritantWear safety goggles, gloves and also protective clothing. If spilt, clean it up using a cloth and water. If gets in contact with skin wash the area thoroughly. If enters eyes wash with clean water. 6Why my plan will Devise Reliable resultsMy plan will devise reliable result because of many reasons. Firstly I am going to do a rough titre in my plan, which means I will have a rough idea of my titration, so when I do my real results I know when to add it drop wise, so that I practise overshoot the end point. Another reason why I wont overshoot the end point is because I am going to use a white tile so I can judge the end point more accurately.Furthermore, I am only going to add 2 or 3 drops of methyl orange indicator. This will make my results more reliable because the methyl orange indicator is slightly acidic, so it would use up the alkaline solution, therefore by only adding a small amount of it will make my results more reliable and accurate.In add ition, I am also going to wash my equipment out thoroughly with distilled water and then with the solution I am going to put that piece of equipment. This will remove any impurities that were originally in the containers so will make my results more reliable.Also, when I am measuring the solution, I will measure accurately by using a pipette to make sure the bottom of the meniscus is on the line to make my results more accurate. Also, when reading the burette I will put a piece of plain paper behind so I can read it more accurately.I will also, remember to take the funnel out of my burette as this could also affect the accuracy of my results. This is because drops are still on the funnel could enter my burette which mean more sulphuric acid affecting my results. This way by removing the funnel, I will strike accurate results. 7Finally, I am going to use accurate equipment as possible, which will minimise errors in my results.Overall my results will be very accurate and reliableRefe rences1. Article on types of chemical reactions, http//www.sky-web.net/science/reaction-types. I used this to help me write my balanced equation for the reaction between sodium carbonate and sulphuric acid.2. Information on the use of indicators in acid-alkali titrations, salters practical assessment. I used this to decide what indicator to use as it told me what to use if I had a strong acid and weak alkali.3. Chemical ideas, 2nd edition, chapter 1, section 1.5, concentrations of solutions, published by Heinemann 2000. I used this to get the concentration equation.4. Power point presentation on moles and concentration, http//moodle.kedst.ac.uk/mod/resource/view.php?id=4556. This helped me find the formulas for concentration and to find out the mass.5. Safety data sheet, http//www.brunnermond.com/products/sodium_carb. I used this source to find out the safety statement of sodium carbonate and the precautions I will need to take.6. Hazard cards, numbers 98 and 32, Cleapps 1998 and 20 03. I used these to find out the safety statement and also the precaution I will need to take when doing my experiment for methyl orange indicator and sulphuric acid.7. Skills for Salters as Chemistry, pages 3,4,6,7 and 29, chemistry department, 2007. I used this to see how I will use my equipment and use it accurately, giving me accurate results.AnalysisI made up my standard solution by firstly weighing out some sodium carbonate.I weighed the weighing bottle and added approximately 2.65g of sodium carbonate. I then transferred the sodium carbonate to a beaker and reweighed the weighing bottle, so I can therefore work out exactly how much sodium carbonate I transferred.Mass of weighing bottle and sodium carbonate = 57.732gMass of weighing bottle after transfer of sodium carbonate = 55.052gConsequently the accurate amount of sodium carbonate transferred is the mass of the weighing bottle and the sodium carbonate, minus the mass of the weighing bottle after the transfer which is57.932 g 55.052g = 2.680gTherefore, 2.680g of sodium carbonate was transferred.Next I added about 50cm3 of water to the beaker and using a glass rod I stirred the solution until the sodium carbonate has dissolved. This was then fully transferred to a volumetric flask and water was added to the 250cm3 graduation mark. I then used a pipette to transfer 25.00cm3 of this standard solution to a conical flask and titrated with the unknown acid.I used 25.00cm3 of the standard solution for each titre after the experiment I had obtained results for how much acid was added for each titre. The results for how much acid I added for each titre are as follows 20.10cm3, 19.85cm3 and 20.05cm3. I am now going to work out an average by picking out the concordant results (results which are in 0.10cm3 of each other) and dividing by how many there is.20.10cm3+ 20.05cm3/2 = 20.075cm3.Therefore, my average titre was 20.075cm3.Concentration of Sodium Carbonate SolutionI am now going to calculate the concentratio n of the sodium carbonate solution2.68g of sodium carbonate was dissolved in a 250cm3 volumetric flask using water, so I need to find out how many moles of the substance I used in order to find out the concentration. Therefore I need to use the equationNumber of Moles= Mass (g)/Molar Mass (gmol-1)Molar mass of Na2CO3 = (23 x 2) + 12 + (16 x 3)= 106gmol-1Number of Moles= 2.680g/ 106gmol-1Number of Moles= 0.0253moles.Therefore, I used 0.0253 moles in my standard solution.I now need to use the equation to find the concentrationConcentration (moldm-3) = Number of moles/Volume (dm3)I firstly need to convert 250cm3 to dm3 so that my equation works1000cm3 = 1dm3250cm3 = 0.250dm3 (I divided by 1000).Concentration (moldm-3) = 0.0253moles/0.250dm3Concentration= 0.101moldm-3Consequently, I have calculated my sodium carbonate standard solution to have a concentration of 0.101moldm-3, rounded to three significant figures.Concentration of acidI am now going to calculate the concentration of the a cid solution therefore I firstly need to find out how many moles there is of the sodium carbonate solution, by using the equationConcentration of Na2CO3 (moldm-3) x Volume of Na2CO3(dm3) = Number of moles of Na2CO30.101moldm-3 x (25/1000) dm3) =0.00253 molesThe equation of my reaction isNa2CO3 (aq) + H2SO4 (aq) Na2SO4 (aq) + CO2 (g) + H2O(l)This equation shows that the molar ratio of sodium carbonate and sulphuric acid is 11 which means is there is 0.00253 moles of sodium carbonate there is 0.00253 moles in sulphuric acid.The average titre as shown above was 20.075cm3, which I need to convert to dm3 which is20.075cm3/1000 = 0.0201dm3.I can now use the equationConcentration (moldm-3)= Number of moles/Volume (dm3)Concentration (moldm-3)= 0.0253 / 0.0201Concentration = 0.126moldm-3.Overall, I conclude that the concentration of the acid solution is 0.126moldm-3.