added and is titrated again with HCl until the color of the solution turns pale

Added and is titrated again with hcl until the color

This preview shows page 2 - 4 out of 4 pages.

added and is titrated again with HCl until the color of the solution turns pale yellow. The solution is then boiled to remove CO 2 , cooled and then titrated again with HCl until it reaches endpoint. For this part, three trials were again conducted. The volume of HCl required to reach the phenolphthalein endpoint was compared to the volume required to reach the methyl orange endpoint. If the two volumes are equal, then the sample contains only Na 2 CO 3 . If the second volume is equal to zero, then the sample contains only NaOH. If the first volume is zero, then the sample contains only NaHCO 3 . If the first volume is greater than the second, then the sample contains a mixture of NaOH and Na 2 CO 3 . Lastly, if the first volume is less than the second, then the sample contains a mixture of NaHCO 3 and Na 2 CO 3 (Table 2). A third mixture that can be formed from the three compounds present is NaOH and NaHCO 3 . This mixture however, will not exist because the two compounds will react to form Na 2 CO 3 and either NaOH or NaHCO 3 -whichever is in excess.
Image of page 2

Subscribe to view the full document.

Table 2. Comparison of HCl vol. at phenolphthalein endpoint and methyl orange endpoint. V 1 vs V 2 Component V 2 = 0 NaOH V 1 = V 2 Na 2 CO 3 V 1 = 0 NaHCO 3 V 1 > V 2 NaOH and Na 2 CO 3 V 1 < V 2 NaHCO 3 and Na 2 CO 3 It was observed in two out of three trials that the volume of HCl required to reach the phenolphthalein endpoint is less than the volume required to reach the methyl orange endpoint. From this observation, it is concluded that the soda ash sample analyzed contained both Na 2 CO 3 and NaHCO 3 . (Table 3) Table 3. Sample Analysis Trial 1 2 3 Sample Weight, g 0.101 ± 0.001 0.111 ± 0.001 0.100 ± 0.001 Net vol. HCl at phenolphthalein endpoint, ml 4.1 ± 0.14 3.1 ± 0.14 4.8 ± 0.14 Net vol. HCl at methyl orange endpoint, ml 7.8 ± 0.14 6.2 ± 0.14 4.3 ± 0.14 V 1 vs V 2 < < > From these data the percent composition of soda ash was calculated with an average of 9.85% for NaHCO 3 and 20.35% for Na 2 CO 3 . The calculated values were inconsistent for the three trials. This was because for every trial, a different person was doing the titration. (Table 4) Table 4. %Composition of Soda Ash % Compositio n of Soda Ash Trial 1 Trial 2 Trial 3 Averag e NaHCO 3 15.23 ± 0.388 11.43 ± 0.388 2.09 ± 0.388 9.58 ± 0.672 Na 2 CO 3 21.3 ± 0.068 14.42 ± 0.068 25.34 ± 0.068 20.35 ± 0.119
Image of page 3
Image of page 4
  • Fall '17
  • Sir Jaden Smith
  • sodium bicarbonate, Sodium hydroxide

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes