patel (rmp932) – Post-Lab 5 Acid/Base Titration – lyon – (51730) This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page – ﬁnd all choices before answering. 001 10.0 points Answer the question to at least six signiﬁcant ﬁgures. A solution of sodium hydroxide is standardized against potassium hydrogen phthalate (KHP, formula weight 204.2 g/mol). From the following data, calculate the molarity of the NaOH solution: mass of KHP 1.404 g; buret reading before titration 0.13 mL; buret reading after titration 38.57 mL. Answer in units of M 002 10.0 points What is the main objective of Part 1 of the experimental procedure? What is the purpose of using KHP in this part of the experiment? 1. The main purpose of Part 1 is to gain practice doing titrations before we titrate our unknown acid in Part 2. KHP is used in Part 1 because we don’t want to use up our unknown acid during the practice titrations, and KHP is an inexpensive alternative to a real acid. 2. The main objective of Part 1 is to determine the concentration of the NaOH solution as accurately and precisely as possible. KHP is used as a titration standard because it is very pure, and can therefore yield highly accurate results for the NaOH concentration. 3. The main objective of Part 1 is to verify the color change of the phenolphthalein at the endpoint of the titration, since we will be relying on phenolphthalein in Part 2 and don’t want to use it without veriﬁcation. KHP is used because it is colorless when dissolved in water, and therefore does not interfere with the color change of the phenolphthalein. 4. The main objective Part 1 is to determine the purity of the NaOH solution. We can determine the percent purity of the NaOH
solution by taking a mole ratio of NaOH to KHP. 5. The main objective of Part 1 is to make sure all the students are paying attention to standard laboratory safety practices before they receive a vial of acid to work with. KHP is used in Part 1 because it poses no health hazard to students who don’t know what they’re doing. 6. The main objective of Part 1 is to condition the phenolphthalein before using it in Part 2. KHP is used in Part 1 because the phthalate in potassium hydrogen phthalate reacts with the phthalein in phenolphthalein to create the pink color that we will need for the unknown acid titration in Part 2. 003 10.0 points The pH of a solution of hydrochloric acid is 2.80. What is the molarity of the acid? 1. 4.2 × 10−2 M 2. 1.6 × 10−3 M 3. 4.2 × 10−3 M 4. 6.3 × 10−2 M 5. 6.3 × 10−3 M 004 10.0 points For the neutralization reaction involving HCl and NaOH, what is the molarity of an HCl solution if 5.5 mL is needed to react with 75 g of a 0.020 M NaOH solution? (density = 1.3 g/mL) 1. 0.21 M 2. 1.5 M 3. 0.34 M 4. 0.0062 M 5. 0.00015 M
patel (rmp932) – Post-Lab 5 Acid/Base Titration – lyon – (51730) 1. 3.8 × 10−4 M 6. 2.5 M 2. 5.1 × 10−10 M 005 10.0 points Which of I) HCl II) HF III) LiOH IV) HClO2 V) HNO3 are strong acids or strong bases in water? 1. I, II, IV, and V only 2. All of the compounds 3. I, III, IV, and V only 1. 11.35 4. I, II, III, and V only 2. 2.43 5. I, III, and V only 3. 4.39 006 10.0 points Write the balanced molecular equation for the reaction of hydrochloric acid with calcium hydroxide. What is the sum of the coeﬃcients? 1. ﬁve 2. seven 3. six 4. three 1. LiClO4 5. four 2. Ba(NO3 )2 007 10.0 points The name of the acid HClO4 is 1. perchloric acid. 2. hypochlorous acid. 3. chloric acid. 4. hydrochlorate acid. 008 10.0 points What is the hydronium ion concentration in a solution having a pOH of 3.62? 3. NaI 4. CsBr2 5. MgCl2 4. 5.5 5. 3.26 3. 4.2 × 10−11 M 4. 3.8 × 10−5 M 5. 2.6 × 10−11 M
009 10.0 points Calculate the pH of a solution with [H3 O+ ] = 5.5 × 10−4 M.
010 10.0 points One of the possible responses to the question below has an incorrect formula. Please change the formula for cesium bromide to CsBr. Which salt is not derived from a strong...
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