During the titration of potassium hydrogen phthalate (KHP, with NaO!, why was th

Question

During the titration of potassium hydrogen phthalate (KHP, with NaO!, why was the phenolphthalein added to the flask? A. To precipitate the acid base reaction. B. To catalyze the acid base reaction D. As an indicator that turned pink, when there was excess base. E. As an indicator that turned pink, whben there was excess acid 27. In a Copper lab experiment, 1.000 g of Cuso, was dissolved in 60.0 ml, of water and treated with a pice of num wire. The resultant copper precipitate was filtered, dried and weighed. The mass of the copper was 0.375 g What is the % yield? A, 37.5 % B. 99.0% C. 94.2 % D. 88.9 % E. 59.0 % 28. In the Copper Lab, how did you know the reaction was complete? A. When the blue color disappeared B. When aluminum no longer formed on the copper wire C. When the aluminum wire dissolved completely D. When the blue color formed E. When the copper was dried in the oven For questions 29-30 : The following data was collected in an Ideal Gas Law experiment Mass of magnesium: 0.0552 g Volume of hydrochloric acid: 10.00 ml Molarity of hydrochloric acid: 2.0 M Atmospheric pressure: 723.5 mm Hg Temperature: 23.0 Volume of gas produced: 25.0 mL 23.0 22.0 E 21.0 E 20.0 19.0 18.0 B. Magnesium is the limiting reactant and 0.00283 17.0 16.0 29. Which of the following statements is true? A. Magnesium is the limiting reactant and 0.00108 C. Magnesium is the limiting reactant and 0.00227 D. HCI is the limiting reactant and 0.00125 mol of E. HCl is the limiting reactant and 0.00201 mol of mol of magnesium chloride is formed mol of magnesium chloride is formed mol of magnesium chloride is formed magnesium chloride is formed magnesium chloride is formed 20.0 21.0 22.0 23.0 24. Temperature (°C) 30. Using the graph of water vapor pressure, above right, what numerical value would be salculated for 'R"? A. 0.08206 L atm B. 0.0142 L a C0034 . 040 04 C. 0.0344 L . 0.440 L E. 0.0354 nol K mol -K mol K mol K mol -K

Explanation / Answer

Answer 26) Phenolphthalein act as an indicator in the titration of potassium hydrogen phthalate (KHP) with NaOH. Phenolphthalein is colourless in acidic solution but shows some colour (pink or red) in basic medium.

The colour of the titrant solution is colourless in acidic medium but as the concentration of NaOH increases in the flask as result pink colour is observed, which indicate equivalent amount of NaOH and KHP.

Therefore correct answer is D

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