Probset for Experiment 4
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Probset for Experiment 4 General Instruction: Write your answers in a bluebook. I. Multiple Choice: Write the letter of the best answer (1.5 pt each) 1. Which of the following statements is/are true about the reaction between Fe 2+ and Ag + ? I. The appearance of a precipitate suggests that the reaction is reactant-favored. II. Appreciable amounts of the reactants are present in the mixture after centrifugation III. A white precipitate is formed when the supernate and HCl were mixed. A. II B. III C. I, II D. II, III 2. Which of the following reagents can be added to decolorize the copper-ammonia system? A. NaCl B. HNO 3 C. KNO 3 D. NH 3 3. When NaOH is added to dichromate: A. an orange solution is formed B. a yellow solution is formed C. the reaction doesn’t proceed spontaneously D. the reaction proceeds to the formation of Cr 3+ II. Modified TRUE or FALSE: Write TRUE if the statement is true. If it’s not, change the underlined statement/phrase to make the statement correct (2 pts each). 1. K 4 Fe(CN) 6 is used as a test reagent for detection of Fe 2+ , with the production of a light violet precipitate as a positive result. K 3 Fe(CN) 6 ==== Prussian blue precipitate 2. CrO 4 2- is converted to Cr 2 O 7 2- at acidic conditions. True 3. The decrease in the color intensity of the iron (III) – thiocyanate system is due to the formation of the pentaaquahydroxoferric (III) ion , upon addition of HCl. 4. The purple solution in the cobalt (II) system suggests that the solution is composed of CoCl 4 2- only . 5. When heat is supplied in an exothermic reaction, the reaction will be product-favored. removed III. Cause and Effect: Determine the effect of the condition on the parameter inside the parenthesis (2 pts each).
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Problem set for Experiment 4, Also Review Quiz
Transcript of Probset for Experiment 4
Probset for Experiment 4
General Instruction: Write your answers in a bluebook.
I. Multiple Choice: Write the letter of the best answer (1.5 pt each)
1. Which of the following statements is/are true about the reaction between Fe2+ and Ag+?I. The appearance of a precipitate suggests that the reaction is reactant-favored.II. Appreciable amounts of the reactants are present in the mixture after centrifugationIII. A white precipitate is formed when the supernate and HCl were mixed.
A. II B. III C. I, II D. II, III2. Which of the following reagents can be added to decolorize the copper-ammonia system?A. NaCl B. HNO3 C. KNO3 D. NH3
3. When NaOH is added to dichromate:A. an orange solution is formed B. a yellow solution is formedC. the reaction doesn’t proceed spontaneously D. the reaction proceeds to the formation of Cr3+
II. Modified TRUE or FALSE: Write TRUE if the statement is true. If it’s not, change the underlined statement/phrase to make the statement correct (2 pts each).
1. K4Fe(CN)6 is used as a test reagent for detection of Fe2+, with the production of a light violet precipitate as a positive result. K3Fe(CN)6 ==== Prussian blue precipitate2. CrO4
2- is converted to Cr2O72-
at acidic conditions.True
3. The decrease in the color intensity of the iron (III) – thiocyanate system is due to the formation of the pentaaquahydroxoferric (III) ion, upon addition of HCl.4. The purple solution in the cobalt (II) system suggests that the solution is composed of CoCl4
2- only . 5. When heat is supplied in an exothermic reaction, the reaction will be product-favored. removed
III. Cause and Effect: Determine the effect of the condition on the parameter inside the parenthesis (2 pts each).
1. Instead of 1.0 M, 0.1 M HCl solution was used to decolorize the copper-ammonia system (drops needed for discoloration)2. H3PO4 was added to chromate instead of H2SO4 (Keq of conversion)3. Instead of NaCl, CaCl2 was added to the iron (III) – thiocyanate system (Keq of the reaction)4. AgNO3 was added to the cobalt (II) system (Q)5. After the appearance of a violet solution, the cobalt (II) system was heated to 50°C (amount of Co2+ present)
