<em>A cylinder of argon gas contains 50.0 L of Ar at 18.4 atm and 127 °C. How many moles of argon are in the cylinder?</em>
<em />
Number moles of Argon : 28.03
<h3>Further explanation</h3>Given
The volume of gas=50 L
P = 18.4 atm
T = 127+273=400 K
Required
moles of Argon
Solution
Use ideal gas Law :
Answer:
Approximately , assuming that this reaction took place under standard temperature and pressure, and that
behaves like an ideal gas. Also assume that the reaction went to completion.
Explanation:
The first step is to find out: which species is the limiting reactant?
Assume that is the limiting reactant. How many moles of
would be produced?
Look up the relative atomic mass of ,
, and
on a modern periodic table:
Calculate the formula mass of :
.
Calculate the number of moles of formula units in of
using its formula mass:
.
In the balanced chemical equation, the ratio between the coefficient of and that of
is
.
In other words, for each mole of formula units consumed, one mole of
would be produced.
If is indeed the limiting reactant, all that approximately
of
formula would be consumed. That would produce approximately
of
.
On the other hand, assume that is the limiting reactant.
Convert the volume of to
(so as to match the unit of concentration.)
.
Calculate the number of moles of molecules in that
of this
.
Notice that in the balanced chemical reaction, the ratio between the coefficient of and that of
is
.
In other words, each mole of molecules consumed would produce only
of
molecules.
Therefore, if is the limiting reactant, that
of
molecules would produce only one-half as many (that is,
) of
molecules.
If is the limiting reactant,
of
molecules would be produced. However, if
is the limiting reactant,
of
molecules would be produced.
In reality, no more than of
molecules would be produced. The reason is that all
would have been consumed before
was.
After finding the limiting reactant, approximate the volume of the produced.
Assume that this reaction took place under standard temperature and pressure (STP.) Under STP, the volume of one mole of ideal gas molecules would be approximately .
If behaves like an ideal gas, the volume of that
of
molecules would be approximately
.