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Qualitative Analysis Lab

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CH 204 – Introduction to Chemical Practice Experiment #1 – Qualitative Analysis of Cations Anam Zaki* Baylee Halliwell TA: Jiawei (Will) He February 16, 2016 RESULTS & DISCUSSION The purpose of this experiment was to use qualitative analysis in order to identify two cation in a solution. During the first part of the experiment, the identity of either silver or lead was revealed, and during the second part, the identity of either calcium or barium was discovered. For the last part of the experiment, many different cations were exposed when Cation Flame Tests were executed. A wooden stick dipped into each solution and was held over a flame, and the color of the flame revealed the cation that was in the solution. For the first part of …show more content…

Hydrochloric acid, HCl, reacted with the cation, Ag+, to form AgCl(s) and H2(g). The AgCl(s) formed was the precipitate that settled towards the bottom of the test tube. The liquid was discarded and 4 ml deionized water was added to the precipitate and was heated in a bath of boiling water. This was done so that if lead were present in the precipitate, it would mix with water because lead chloride is soluble in hot water. Lead would be in the liquid part of the solution instead of staying in the solid precipitate form. In the second part of the experiment, potassium chromate, K2CrO4, was mixed into a solution to test whether or not barium was present in the solution. If barium was present, then the negatively charged chromate anion would have reacted with barium to form a yellow precipitate, BaCrO4. In step 12, a false positive could have occurred. The OJP Drug Court Clearinghouse and Technical Assistance Project describes a false positive as a result that would not be proven if further tests were performed.1 If a precipitate was formed, and it tuned into a white precipitate after step 13, it is still necessary to perform step 14. This is because if a white precipitate is formed after step 14, then the solution contains calcium. It was important to perform step 14 because barium could have been incorrectly identified. If …show more content…

Silver: Formula Unit:[Ag(〖NH_3)〗_2 ]Cl_((aq))+2H〖NO_3〗_((aq))→AgCl_((s))+2NH_4 〖NO_3〗_((aq)) Total Ionic Equation:〖Ag^+〗_((aq))+〖〖〖2NO〗_3〗^-〗_((aq))+〖2H^+〗_((aq) )+〖Cl^-〗_((aq))→AgCl_((s))+2N〖〖H_4〗^+〗_((aq))+2〖〖NO_3〗^-〗_((aq)) Net Ionic Equation:〖Ag^+〗_((aq))+〖Cl^-〗_((aq))→AgCl_((s)) Calcium: Formula Unit: Ca(〖〖OH)〗_2〗_((aq) )+〖K_2 C_2 O_4〗_((aq) )→〖CaC_2 O_4〗_((s) )+2KOH_((aq)) Total Ionic Equation: 〖Ca^(2+)〗_((aq))+O〖H^-〗_((aq) )+〖K^+〗_((aq) )+〖〖C_2 O_4〗^(2-)〗_((aq))→〖CaC_2 O_4〗_((s))+2〖K^+〗_((aq))+2〖OH^-〗_((aq)) Net Ionic Equation: C〖a^(2+)〗_((aq))+〖〖C_2 O_4〗^(2-)〗_((aq))→C〖aC_2 O_4〗_((s)) REFERENCES Drug Testing in a Drug Court Environment: Common Issues to Address. https://www.ncjrs.gov/pdffiles1/ojp/181103.pdf (accessed Feb. 14, 2016). Dogancay, D. Flame Tests Performed Safely: A Safe and Effective Alternative to the Traditional Flame Test. Sci Teach [Online] 2005, 72,

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