Determining a substance by tritration Essay

AimUsing the procedures of a standard acidulous base titration lab, the name and wreakress of this experiment is identifying the amount of Calcium carbonate (CaCO3) that is presented in a atomic number 20 change bosom presented by our teacher.HypothesisDue to any unknown substance that we encounter in the chemistry room, we moldiness take serious precaution, as the substance may very well be highly contagious and heartbreaking to smell, touch or taste directly. The only ability that we posses that can be used to observer this substance is our vision that is going to help us in determining the concentration of the substance. Although that with vision only, it will not suffice the need that is necessary to make that judgment as we need quantitative data (finding the call for concentration of calcium carbonate). Unless we render prior knowledge about this substance, the processes of a titration must be used. My hypothesis begins that this has about 60% concentration.VariablesIn dependent Variable at that place is none in this experiment. The goal of this lab is not to include any variables that will change the concentration of the calcium carbonate. We need constant results for the concentration of the calcium carbonate, as that will determine the actual concentration of the calcium carbonate in our substance.Dependent VariableThe volume needed to titrate the calcium carbonate resolving by utilise the phenolphthalein indicator. Though it is a clear substance, the indicator will change its color into pink when the solution becomes a base from an acid. By determining the amount of hydrochloric acid is needed to change the color of the solution, we can determine the concentration of calcium carbonate through some deliberatenesss.Controlled Variables1. The Distilled Water The distilled piss will be the only water that will be used during the entire experiment. The distilled water was prep ared and resented by our teacher.2. The calcium carbonate substance The calcium carbonate substance was constant throughout the entire experiment.3. The Hydrochloric Acid The hydrochloric acid was one of the main components of this experiment. Therefore this acid was also prepared and presented by the teacher.4. all told Equipment All the same equipments such as the pipette and the filter subject were used throughout the experiment.Apparatus* Unknown white powdered substance* 50cm3 burette* 3 250cm3 Erlenmeyer flask* 200cm3 for hydrochloric acid* 0.1M of Sodium Hydroxide* Burette clamp* Retort stand* Distilled water* Goggles* strive paper* A funnel* Phenolphthalein indicator* A scale* Paper towel* A spoon* Pipette* Pipette sucker* White paperMethod1. First compensate up the retort stand and the retort clamp as indicated by the diagram below. Of course, the flask must be prepared in the subsequent steps. except unlike the diagram, place a white piece of paper beneath the flask so that the color change becomes more easily visible.2. After placin g the paper towel and scaling the scale, measure out approximately 10.0 grams of the unknown substance and record the exact mass3. Add 200cm3 of 1.00-mol dm-3 hydrochloric acid and stir until the reaction is complete.4. Filter the solution and withdraw 10cm3 using a pipette and make up to 100 cm3 in a volumetric flask.5. Titrate 10cm3 portions against a standard 0.1M NaOH using the phenolphthalein indicator.6. Record both quantitative and qualitative data.7. Repeat the process of titration three durations.Observation (Data Collection)Measurements* Mass of Calcium Carbonate solution* Burette Calcium Carbonate solution made using 250cm3volumetric flask with an uncertainty of ?0.5cm3* Pipette 25.0cm3 of 0.100moldm-3 NaOH(aq) ?0.04cm3Chemical EquationsBefore we delve into the calculations, it is best that we list the necessary chemical equations of this lab. One must note that in this experiment, that there were two chemical reactions. Firstly, the first experiment occurs when the whi te substance mixed with the HCl. The second chemical reaction took place when the HCl solution meets with the .1M of NaOH1.2.Qualitative DataDescription of the substance used and producedHydrochloric AcidClear, viscous,Calcium CarbonateWhite, powder formPhenolphthalein IndicatorClear solution, comes in a bottle, add as dropsSolution Produced in the endBubbly, white liquid, most of the unknown mixture dissolvedClear/pink throughout.Quantitative DataMeasurement preserve During the ExperimentTrial1234*Initial Burette Reading(ml?0.05cm3)0.000.000.000.00Final Burette Reading(ml?0.05cm3)5.455.905.605.40*To note, for the calculations below, the supervisor at the time suggested the best data to use would be the average of the HCl used because the numbers found were very consistent.CalculationsThe following steps were taken so to find the % by mass of CaCO3 in the mixture1. The moles of acid presented in 200cm3of 1.00 mol dm-3hydrochloric acid.2. The moles of acid presented in 10cm3of the a cid solution titrated.0.00056molof HCl3. Multiply the volume present in the volumetric flask.4. The total moles acids remaining after the reaction with CaCO35. Subtract the value in 4 from that obtained in 1 to find moles acid used.6. The stochiometric equation for the reaction of HCl and CaCO3Hydrochloric acid+Calcium carbonateCalcium chloride+water+Carbon dioxide-Therefore the molar ratio is 1 mole of calcium carbonate to 2 moles of hydrochloric acid7. Using this and the value in 5 to calculate the moles of CaCO3 present. Then calculate the mass of CaCO38. Using the value found in step 7 and the original mass of the mixture, here is the calculation to find percent of the mixture is made up of CaCO3Uncertainties****Total Uncertainty=ConclusionThis experiment in general was very interesting. During this lab, I was able to check of how we can identify the amount of a substance by knowing the concentration and volume of another. We were able to do so as we knew the moles and concentr ation of atomic number 11 hydroxide that had enabled us to find the unknown concentration of calcium carbonate.Because the actual percentage of CaCO3 was not given, we must concur that the accuracy of this lab has been affected and whence must be assessed by our uncertainty percentage. The percent of uncertainties represents the desultory errors that may have occurred, which either may make the measurements bigger or smaller than the pass judgment value, due to imprecise measurement. One way to avoid future random errors, better equipment may be needed, or repetition of the measurements. Despite the uncertainties based on lab equipments and other mediums of measurements, one of the biggest possible sources of error lies in the systematic errors of this lab, especially finding the exact terminal.Though the pink color should indicate when the endpoint is reached, in trial 2 and 3, the solution turned a faint pink color and my partners and I did not know whether that faint pink ind icated the endpoint. This could have resulted in a measurement lower than the actual value. To possibly improve this source of error, I believe more time and trials should be allotted to the students. When I was doing my experiment, we were only given a single class time to follow the procedures, write down our notes, and ashen up our experiment. If more time was allotted, then higher(prenominal) quality recordings could be made. This would then give us a clearer idea when the endpoint actually is.Next, though it is unlikely, to improve this lab we may have to sponge the burettes and other flasks prior to performing this lab. In my chemistry classroom, burettes and flasks are arranged so that the clean ones are clearly seen and labeled while the used ones are in the sink. However it could be possible that another student may have placed an unclean burette in the cabinet full of clean equipments. Therefore, for accuracy purposes, all equipment should be washed using soap and tissue s.Reviewing and understanding the errors can significantly improve this experiment. Though my hypothesis of the concentration being 60% calcium carbonate was wrong, this experiment taught me the value and usefulness of the process of titration.