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Given: Solution:

3
V (Cl 2) = 0,56 m The quantity of substance is determined by the
n.c. V
formula   .
to determine: V m

ν (Cl 2) – ?

3
Since the molar volume of gas is usually expressed in dm /mol, the
volume is converted to dm 3.

3
0,56 m = 560 dm 3.
Then V= 560/22,4=25 mole

Answer: ν (Cl 2) = 25 mole.

3
Example 6. How many molecules are contained in 56 m of oxygen under

normal conditions?

Given: Solution:
3
V (О 2) = 56 m To determine the number of molecules we use the

n.c. N V
formulas:  ; 
N V
to determine: A m

N (О 2) – ?

V
Then =: N   N  N
A
A
V
m
3
Since the molar volume of gas is usually expressed in dm /mol, the
3
volume is converted to dm .
3
3
56 m = 56 000 dm
56000 23 27
Then N  , 6  02 10  5 , 1  10
22 4 ,

27
Answer N (О 2) = 1,5·10 molecules

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