# Chemistry

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Thanks for the help earlier

My question

Silicon tetrachloride (SiCl4) can be prepared by heating Si in chlorine gas:

Si + 2Cl2 yields SiCl4

In one reaction 0.507 mole of SiCl4 is produced. How many moles of molecular chlorine were used in the reaction?

Ok is it makeing reference to the Chlorine in reactants or products

also the answer in the back of the book says 1.01 mol of Cl2 so I guess its the reactants it makeing reference to

Now I am kind of confused because I thought there were 2 moles of carbon in the reactants

I thought I was suppose to do something like this

1 mole of Si is stoichiometrically equivalent to 2 moles of Cl2

from which I can set up a fraction but apparently that is wrong...

I kind of don't know how to start this problem can you help me thanks

• Chemistry -

Ok apparently its just the mole ratio 2:1 from the coefficents

so I just do 2(.507) to get my answer but how come I ignoered the coeficent of the Si in ther reaction?

• Chemistry -

Silicon tetrachloride (SiCl4) can be prepared by heating Si in chlorine gas:

Si + 2Cl2 yields SiCl4

In one reaction 0.507 mole of SiCl4 is produced. How many moles of molecular chlorine were used in the reaction?

Ok is it makeing reference to the Chlorine in reactants or products
It's making reference to moles Cl2 in the reactants. That's the only place MOLECULAR chlorine is found. There is no molecular chlorine in SiCl4

also the answer in the back of the book says 1.01 mol of Cl2 so I guess its the reactants it makeing reference to

Again, yes. 0.507 moles SiCl4 x (2 moles Cl2/1 mole SiCl4) = 0.507 X (2/1) = 1.01 moles.

Now I am kind of confused because I thought there were 2 moles of carbon in the reactants
There is no carbon in the entire reaction. The C you have there goes with the l to make Cl which is chlorine.

I thought I was suppose to do something like this

1 mole of Si is stoichiometrically equivalent to 2 moles of Cl2

from which I can set up a fraction but apparently that is wrong.
The process is ok and the answer you get is the correct answer but you arrived at it incorrectly. The question is about SiCl4 and Cl2 and has nothing to do with Si in this part of the problem. See the earlier fraction I set up and you get 0.507 x 2 = 1.01 moles Cl2.

I kind of don't know how to start this problem can you help me thanks

* Chemistry - Kate, Saturday, July 3, 2010 at 10:38pm

Ok apparently its just the mole ratio 2:1 from the coefficents

so I just do 2(.507) to get my answer but how come I ignoered the coeficent of the Si in ther reaction?
The problem is about the product, SiCl4, and not about Si. It follows from the stoichiometry that 1 mole SiCl4 = 1 mole Si; therefore, if you had stoichiometric quantities, then 0.507 moles SiCl4 would have begun with 0.507 moles Si.

• IChO -

(((((()))))))))))))))
((((((((())))))))))))
Coefisient : 1 --> 2
x0.507 ----> 0.507 --> 1.014 gram
1.014 gram must be rounded
in 3 SCIENTIFIC NUMBER ---> 1.01 GRAM

MUST BE 3 IMPORTANT NUMBER

• Chemistry -

you have the mole : .507

so

cl2 :cl2 ::sicl4:sicl4
2 :x ::1 :.5o7

x*1=2*.507
x= 1.01 mole of cl2

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