VSEPR theory predicts that the molecular geometry (shape) of XeF 4 is A. square
ID: 1040030 • Letter: V
Question
VSEPR theory predicts that the molecular geometry (shape) of XeF4 is
A. square planar
B. square pyramidal
C. trigonal bipyramidal
D. t-shaped
_____ 20. In the vinegar titration experiment, the student does not fill the buret tip before titrating. How would this affect the molar concentration calculation of the acetic acid?
A. No change
B. The molarity would increase.
C. The molarity would decease.
D. The indicator would not work properly.
_____ 21. Which of the following statements is incorrect?
A. An acidic solution turns blue litmus paper red.
B. A basic (or alkaline) solution turns red litmus paper blue.
C. Phenolphthalein is pink in acidic solution but colorless in basic solution.
D. Phenolphthalein is pink in basic solution but colorless in acidic solution.
A student carried out the Synthesis of Alum experiment and obtained a percent yield
of 62.1%. If the mass of the student's product was 3.916 g, calculate the student's
theoretical yield for alum.
4. Tartaric acid, H6C4O6 (aq), is present in grapes and unripe fruit and reacts with potassium permanganate, KMnO4, and hydrochloric acid in the following way:
2 KMnO4 (aq) + H6C4O6 (aq) + 6 HCl (aq) Þ 2 MnCl2 (aq) + 2 KCl (aq) + 6 H2O (l) + 4 CO2 (g)
An unknown sample containing tartaric acid reacts with excess potassium permanganate at 22.0°C and 680.0 mmHg. The resulting carbon dioxide gas was collected under conditions similar to the Analysis of Alka-Seltzer experiment carried out in lab.
(3) a. If the vapor pressure of water at 22.0°C is 19.8 mmHg, what is the pressure of the carbon dioxide gas in the experiment described above?
(5) b. If the volume of carbon dioxide obtained is 39.15 mL, calculate the number of moles of carbon dioxide gas.
(4) c. What mass of tartaric acid must be present in the experiment described above?
(4) d. What is the mass percent of tartaric acid in the unknown sample if 0.1200 g of the unknown was used?
Explanation / Answer
19.
(A) Square planar.
Xe undergoes sp3d2 hybridisation and Xe has two lone pairs on it and hence XeF4 is in squate planar geometry.
20.
A. No change. It does not depend on the complete filling of burette. It is sufficient to measure initial burett reading and final burete reading. The difference will give volume consumed.
21.
(C) is incorrect
Phenolphthalein is pink in basic solution and colorless in acidic solution.
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