Cliffs AP Chemistry, 3rd Edition

(singke) #1
(a) (2) Restatement: Find partial pressure of each gas.
Ptotal= Pfluorine+ Pxenon

.

..
P nRTV
80 10

4 868 0 0821 273
mole K liters

moles liter atm K
flourine 1
xenon
::#

:: :::
= = =1.4 atm

.

..
P nRTV
80 10

4 0 0 0821 273
mole K liters

moles liter atm K
xenon 1
xenon
::#

:: :::
= = =1.1 atm

(b) Restatement: 23.00 g Li added to flask. Weight of LiF formed?
Xe is inert (no reaction with lithium).
The balanced equation for the reaction is thus F 2 (g) + 2Li(s) →2 LiF(s).
.
1. .Li

23 00
694

gLi (^1331)
gLi


mole Li= mole


Therefore, lithium is the limiting reagent. So 3.31 moles of Li is used up along with
3.31/2 or 1.66 moles of F 2. This leaves 3.21 moles (4.868 −1.66) of F 2.


..






331
2

2
1

25 94
860
moles Li
moles Li

moles LiF
mole LiF

g LiF
##= g LiF

(c) Restatement: Partial pressures of gases present after reaction, 0°C
Xenon is inert (no reaction): 1.1 atm pressure

.

..
P nRTV
80 10

3 21 0 0821 273
mole K liters

moles liter atm K
fluorine 1
fluorine::
::#

:::
== = 0.90 atm

Part II: Specific Topics

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