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REVIEW ACS IV

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Question 1

What volume (in mL) of 12 M HCI solution is required to prepare exactly 500. mL of a 0.67 M HCI solution?

Correct

 

Explanation

M1V1=M2V2


(12 M ) (V1) = (0.67 M) (500 mL)


V1 = (0.67 M)(500 mL) / (12M)


V1 = 27.91

 

Question 2

What is the molar mass of an ideal gas if a 0.800 g sample of this gas occupies a volume of 200. mL at 50.0 oC and 720. mm Hg?

Select one:
 Correct

 

Explanation

P = 720 mmHg/ 760 = 0. 947 atm


 PV = nRT 

n = PV/ RT  


n = (0.947 x 0.2L) / ( .08206 *323) = 0.007 mol CaCO3


0.007 mol CaCO3 x ( 1 mol CO2/ 1 mol CaO ) = 0.007 mol


0.800 g / 0.007 mol = 111.9 g/mol

 

Question 3

Which set of temperature and pressure conditions will cause a gas to exhibit the LEAST deviation from ideal gas behavior?

Select one:
 Correct

 

Explanation

High temperature and low pressure exhibits the least deviation from ideal gas

 

Question 4

What is the molarity of a solution made by dissolving 3.49 g of sodium acetate in water and diluting to 750. mL? (molar mass NaC2H3O2 is 82.0 g/mol.)

Correct

 

Explanation

3.49g x ( 1 mol / 82.08 g) = .0425 mol 


0.0425 mol / .75 L = 0.0567 mol / L

 

Question 5

An open-ended mercury manometer is used to measure the pressure exerted by a trapped gas as shown in the figure. Atmospheric pressure is 750. mmHg. What is the pressure (in mmHg or torr) of the trapped gas if h =3 cm?

Correct

 

Explanation

h = 3 cm = 30 mm


P total = 750 mmHg + 30 mmHg = 780 mmHg

 

Question 6

Select one:
 Correct

 

Explanation

A solution is a mixture where solutes and solvents are equally mixed.

 

Question 7

Which substance meets the requirements: crsytalline solid; brittle; poor electrical conductor in the solid state; good conductor in liquid phase; melts at high temperature?

Select one:
 Correct

 

Explanation

An ionic compound conducts electricity in liquid (dissolves) and solid. Also it melts at high temperature. 

 

Question 8

The boiling point of an impure compound is generally

Select one:
 Correct

 

Explanation

An impure compound usually has extra solutes that increases intermolecular forces between solutes and solvent

 

Question 9

Given the cooling curve of one gram of a pure liquid, the length of the line BC depends on

Select one:
 Correct

 

Explanation

Line BC has a flat slope this means temp is not changing. Instead, the object is going through a phase change. In this case the object is going from solid to liquid (melting)

 

Question 10

Starting at point A and ending at point F, which of the following processes requires the most energy?

Select one:
 Correct

 

Explanation

 

Question 11

Which phase has the largest specific heat? (Hint, how are the slope and specific heat related?)

Select one:
 Correct

 

Explanation

liquid phase has the steepest slope so it has the largest specific heat. 

 

Question 12

Copper crystallizes in a face-centered cubic lattice. What is the mass of one unit cell? Report your answer in grams.

Select one:
 Correct

 

Explanation

NO POINTS

 

Question 13

Metal M crystallizes in a face-centered cubic lattice. If the edge of the unit cell is 200 pm, what is the radius of a metal M atom (in pm)?

Select one:
 Correct

 

Explanation

NO POINTS

 

Question 14

A 500. mL gas sample is collected over water at a pressure of 740 mmHg and 60 °C. What is the volume of the dry gas at STP? (STP = 1 atm and 0 °C.) Vapor pressure of water at 60. °C is 149 mmHg.

Select one:
 Correct

 

Explanation

740 mmHg - 149 mmHg = 591 mmHg


PV= nRT 


PV/ RT = PV/ RT


(.778) (.5) / (.08206) (333) =  (1) (V) / (.08206)(273) 


V =  (.778) (.5) (.08206)(273) / (.08206) (333) (1) = 320mL

 

Question 15

Which point corresponds to the critical temperature and pressure?

Select one:
 Correct

 

Explanation

 

Question 16

Starting at point A and lowering the pressure at constant temperature is best described by

Select one:
 Correct

 

Explanation

 

Question 17

Which of the following conditions are possible at point C?

Select one:
 Correct

 

Explanation

Triple Point is where all phases exist (solid, liquid, gas)

 

Question 18

Which of the following statements is NOT correct?

Select one:
 

 

Explanation

At the critical point the supercritical fluid does not phase change

 

Question 19

Which factor affects the vapor pressure of a liquid?

Select one:
 Correct

 

Explanation

  • vapor pressure of a liquid varies with its temperature
  • As the temperature of a liquid or solid increases its vapor pressure also increases. 
  • Vapor pressure decreases as temperature decreases.


 

Question 20

The graph shows how the vapor pressure of a liquid Changes with temperature. At 500 torr, what is the boiling temperature?

Select one:
 Correct

 

Explanation

Just look at the graph

 

Question 21

What is the vapor pressure of a solution with a benzene to octane molar ratio of 1:3 at 50 °C? At 50 °C, the vapor Pressure of pure benzene and octane are respectively 280 mmHg and 400 mmHg.

Select one:
 Correct

 

Explanation

Your content goes here...

 

Question 22

A particular solid is soft, a poor conductor of heat and electricity, and has a low melting point. Generally, such a solid is classified as

Select one:
 Correct

 

Explanation

Your content goes here...

 

Question 23

Which solution is the most concentrated.

Select one:
 Correct

 

Explanation

High concentration: more solute particles less water molecules 


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