Thursday, August 15, 2019

Analysis of Brick Cleaner Essay

Aim: To find the percentage by mass of hydrochloric acid present in brick cleaner by doing an acid-base titration. Theory/Hypothesis: The main ingredient in brick cleaner is HCL and must be diluted and titrated with a base to be able to analyse it. It reacts with parts of the concrete which allows it to remove the concrete from the bricks. I think there will be around 30% of HCL in brick cleaner. Materials: * 5mL brick cleaner * 100mL, 0.1M standard sodium carbonate solution * 250ml de-ionised water * Methyl orange indicator * 250mL volumetric flask * 4x100mL conical flasks * Small funnel * 10mL measuring cylinder * 20mL pipette * Pipette filter * Dropping pipette * Burette and stand * White tile * Electronic balance * Safety glasses * Gloves Method: 1) A 250 mL volumetric flask was weighed with it’s mass recorded 2) A 10mL measuring cylinder was used to pour 5mL brick cleaner into the volumetric flask. The flask was stoppered straight after all the brick cleaner was in the flask. 3) The flask was then reweighed 4) De-ionised water was added until the flask was about half full. The flask was stoppered and shaken carefully upside down several times. 5) More water was added to the flask about a cm below the graduation line. A dropper was used to accurately drop the right amount of water to the flask so the bottom of the meniscus was on the graduation line. 6) A 20mL pipette was used to put 20mL of sodium carbonate solution into each of the four 100mL conical flask. 3 drops of methyl orange indicator was added to each. 7) The burette was filled with the solution of brick cleaner. 8) The sodium carbonate solution was titrated with the solution of brick cleaner until there was a clear permanent colour change. 9) Steps 7 and 8 were repeated until 3 concordant results were Results: Weight Volumetric flask 78.968g Brick cleaner 6.00g Titre 1 2 3 Initial vol 2.3 23.4 3.0 Final vol 23.4 44.5 24.0 Vol added 21.1 21.1 21.0 Calculations: On page attached. Discussion: The weight for the brick cleaner may not be 6.00g as the volumetric flask was not weighed again with the brick cleaner in it because that step was forgotten. So the result above was taken from another student that did the prac. This will affect the results as the mass of the brick cleaner is used to determine the percentage by mass of HCL in brick cleaner. All 3 titres show that they are only within 0.1 of each other. The hypothesis has been disproved because it was suggested the 30% of HCL would be in brick cleaner and there’s only 2.4% although it’s not certain that those steps were done correctly. There were no problems encountered during this prac. Focus Questions: 8)a) the manufacturer says that brick cleaner is made up of around 35% HCL, which is a massive difference to the answer that was got in this prac but again question 7 was not done correctly. b) differences in class results occur because not everybody would have done the exact volume of brick cleaner, sodium carbonate etc as each other therefore the difference in results obtained. 9) To correctly clean up a spill of 20mL brick cleaner you would mop it up immediately, washing it away with massive amounts of water 10)a) volumetric flask= once with water twice with brick cleaner b) Burette= once with water twice with diluted solution of brick cleaner c) pipette= once with water twice with diluted brick cleaner d) conical flask=once with water twice with sodium carbonate solution Conclusion: To conclude, there should be 35% HCL in brick cleaner although it was found that there was only 2.4%

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