Ch. 10 gas         test                 [60 points]                                           AP Chem

 

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.  Clearly identify the problems done and do them in sequence and your answer must begin and end on the same page of paper; otherwise, you will lose points.  attach this sheet to the front of your exam.

 

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 1.  A syringe has a volume of 23.0 mL and open to the atmosphere, where it’s pressure is 755 torr and temperature is 21.0 °C.  The syringe was sealed, then transferred to a refrigerator at 4.0 °C.  What is the pressure in the syringe in the refrigerator ?  [10 points]

 

 

2.  Heating a sample of potassium chlorate, KClO3, generates potassium chloride and oxygen gas.  The gas was collected over water (see below figure – it’s figure 10.13 in your textbook).  Based on the following hypothetical experimental data:  [similar to sample example 10.11 in your textbook; 20 points]

 

Volume of gas = 250.0 mL

Room temperature = 26.0 °C

Atmospheric pressure = 755 mm Hg

Height of water in the beaker = 25 cm water [assume: 10.3 meters of water = 1.0 atm]

 

   

 

[image source:  http://wps.prenhall.com/wps/media/objects/3311/3391331/blb1006.html]

 

 

 

 

 

a.  what is the pressure of the gas in the container ?

 

b.  what is the partial pressure of oxygen in the container ?

 

c.  what is the number of moles of oxygen in the container ?

 

d.  what is the number of grams of KClO3 that was heated ?

 

 

3.  An alkane effuses about 5.385 times slower than hydrogen gas.  The complete combustion of 1.0 g alkane produces 1.552 g of water and 3.793 g of carbon dioxide.  What is the chemical name of the alkane ?  [20 points]

 

 

4.  old topics  [10 points]

 

a.  write the balanced net ionic equation to describe the addition of solid aluminum into a concentrated solution of ammonia.

 

b.  define the terms, Lewis acid & coordinate number

 

c.  identify the Lewis base in the reaction