Calculations for titration.

Titration calculations? Revised?

• Heres what we did: Provided with a standard 0.01M solution of sodium carbonate Exactly 25.0cm3 of the approximate 2M hydrochloric acid was very carefully diluted using a bulb pipette. The meniscus was exactly on the line of 25.0cm3 on the pipette. The hydrochloric acid was transferred into a 250cm3 volumetric flask and filled to the mark with distilled water. The flask was shaken to mix the solution and the flask labelled. A burette was rinsed with distilled water and then filled fully to the mark with the diluted hydrochloric acid. A rinsed pipette was used to transfer 25cm3 of sodium carbonate solution to a rinsed titration (conical) flask. A few drops of methyl orange indicator was used to turn the solution a yellow colour. The hydrochloric acid was titrated into the sodium carbonate solution until the indicator changed, marking the end point, the solution changed into a peach colour solution. Burette readings were recorded The process was repeated until three concordant results within ±0.05cm3 was achieved and recorded 2HCL(aq) + Na2CO3(aq) à 2NaCl(aq) + H2O(l) + CO2(l) Final burette reading:24cm3 Calculate molarity of hydrochloric acid and concentration in g/dm3. This is all the info we were given. Please show some working out as im unsure how to do this. Thanks alot!

• Answer:

  moles of Na2CO3 = M x V = .01 mole liter ^-1 x .025 liter = 0.00025 moles we see from the equation that these react with 0.00025 x 2 moles of HCl = 0.00050 these were in 24 ml of solution which came from a 250 mL flask so moles of HCl in the 250 mL flask = 0.00048 x 250 / 24 = .0050 moles these all came from a 25 mL pipette so moles of HCl per liter of the original solution = 0.0050 x 1000 / 25 = .2 M