indicates that all that any strong bases in addition to CO 3 2 has been used up

Indicates that all that any strong bases in addition

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indicates that all that any strong bases in addition to CO 3 2- has been “used up”. [2] At this point only HCO 3 - remains. Methyl orange changes the solution color also at the point when all the HCO 3 - is used up. Therefore, the amount of HCl used indicates the amount of HCO 3 - to react with. The HCl has a 1:1 mole ratio with OH- and CO 3 2- (with respect to the first reaction only).Therefore, the amount of HCl used indicates the amount of CO 3 2- to react with. If the solution contains just Na 2 CO 3 , the moles of CO 3 2- is the same as the total amount of HCO 3 - that can be generated as the solution is titrated. If the amount of HCl used in the first titration (amount to reach the phenolphthalein indicated pH) is greater than the second titration (amount to reach the methyl orange indicated pH), it means that the solution contains strong bases in addition to Na 2 CO 3 . If the HCl used in the first is less than the second, it means that there is more HCO 3 - than CO 3 2- ; and the solution contains Na 2 CO 3 and amounts of NaHCO 3 . If they are equal, then only Na 2 CO 3 is present. If the solution is immediately colorless at the addition of phenolphthalein, there is no Na 2 CO 3 present and it contains only NaHCO 3 . If after the first titration, the solution is already orange, that means that there was no Na 2 CO 3 and it only contains a strong base. [3] Soda Ash is an impure solution of Na 2 CO 3 , it may contain small amounts of Na 2 CO 3 or NaOH. The results of the titrations are shown in table 1. Table 1: Titrant used in each trial Volume of HCl used 1st Titration 2nd Titration Trial 1 1.7 3 Trial 2 2.9 4.3 Trial 3 2.5 3.6 Averag e 2.3666666 67 3.6333333 33 From this we can conclude that the solution contains Na 2 CO 3 and NaHCO 3 .
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  • Fall '17
  • Sir Jaden Smith

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