2. Because the student added too much nitric acid, he attempted to compensate by
ID: 537363 • Letter: 2
Question
2. Because the student added too much nitric acid, he attempted to compensate by adding more sodium hydroxide, as well. He added 20.0mL of 6.0M NaoH. Was this enough sodium hydroxide to neutralize the excess nitric acid after the copper reaction from the question above? 3. Would you expect litmus paper to be red or blue, ifadding the amount of NaoH from question 2 to the copper and nitric acid reaction mixture in the laboratory procedure? Based on this litmus paper result, what is the appropriate action to complete step 2 of this laboratory? 4. What would the solution look like after adding 20.0 mL of 6.0M NaoH described in question 2? Describe the color of the solution and state ifany precipitate will be present. You may need to consult your observations from the laboratory to answer this question. 5. What would be the effect on the percentage recovery if not enough NaOH was added in Step 2 to react with both the unreacted HN0, and the Cu that are present at the end of Step 1? Explain your answer. 6. Given a solution containing a tin salt, would you be able to recover the tin its elemental form? Please discuss your answer. Consult the activity series in Chapter 4 of your text. REFERENCES: Roberts, Hollenberg, Postma, General Chemistry in the Laboratory (pp. 67-74), modified by the ARC Chemistry Department Condike, G.F., J. Chem. Educ. 52:615, 1975Explanation / Answer
2. Given HNO3 remained in the solution is 0.12 moles
20 mL 6M NaOH contains (6/1000) * 20 = 0.12 moles
Since one mole nitric acid reacts with one mole NaOH,.the amount of NaOH added is exactly equals to neutralize excess nitric acid present in the solution.
3. As we discussed earlier, immediately after the reaction with Cu, the solution was acidic due to the presence of excess nitric acid. At this stage, litmus will show a red color. Generally, in acidic pH litmus paper show a red color.
If we are adding NaOH to this solution, the intensity of the red color of the litmus decreases and at one point the color will remain as blue. This is the neutralization point. (Note: don't add more NaOH. I meant drop by drop addition of NaOH and checking with litmus)
4. Since nitric acid and NaOH reacted completely. The solution shows the properties of copper nitrate The copper nitrate salt solution is deep blue in color. The other salt formed is NaCl it is also highly soluble in water. Thus, I am not expecting any precipitate.
As per the policy of Chegg one question or 4 sub-parts of a question will be answered
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