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nbaker53
Dec 15th, 2006, 05:01 AM
I know this is so basic, but I forget:

Which contains the same number of ions as the value of Avogadro's constant?
A) 0.5 mol NaCl
B) 0.5 mol MgCl2
C) 1.0 mol Na2O
D) 1.0 mol MgO

Apparently the answer is A, but I dunno why!

nbaker53
Dec 15th, 2006, 05:13 AM

LeRoy.
Dec 15th, 2006, 05:16 AM
1 mol NaCl ---> `1 mol Na+ ions and 1 mol Cl- ions = 2 mol of ions = 2* Avogadro # of ions

0.5 mol NaCl = total of 1 mol of ions = Avogadro # of ions

0.5 mol of MgCl2 --> 1.5 *Avogadro # of ions
1 mol Na2O --> 3*Avogadro # of ions
1 mol MgO --> 2*Avogadro # of ions

nbaker53
Dec 15th, 2006, 05:20 AM
1 mol NaCl ---> `1 mol Na+ ions and 1 mol Cl- ions = 2 mol of ions = 2* Avogadro # of ions

0.5 mol NaCl = total of 1 mol of ions = Avogadro # of ions

So, you take the 2 x Avogradro's #
and then multiply by 0.5?

Also another question:

CO2 +3H2 --> CH3OH + H2O

What is the maximum amount of methanol that can be formed from 2 mol of carbon dioxide and 3 mol of hydrogen?

A) 1 mol
B) 2 mol
C) 3 mol
D) 5 mol

LeRoy.
Dec 15th, 2006, 05:23 AM
1 mol of CH3OH

nbaker53
Dec 15th, 2006, 05:24 AM
1 mol of CH3OH

And how'd you get that? :angel:

LeRoy.
Dec 15th, 2006, 05:26 AM
And how'd you get that? :angel:

from the eqn

1 mol of carbon dioxide with 3 mol of hydrogen gives 1 mol of methanol

2 mol of co2 would require 6 mol of h2 to give 2 mol of methanol

2 mol of co2 with 3 mol of h2 would give 1 mol of methanol and the extra mol of co2 will remain unreacted

nbaker53
Dec 15th, 2006, 05:28 AM
from the eqn

1 mol of carbon dioxide with 3 mol of hydrogen gives 1 mol of methanol

2 mol of co2 would require 6 mol of h2 to give 2 mol of methanol

2 mol of co2 with 3 mol of h2 would give 1 mol of methanol and the extra mol of co2 will remain unreacted

I don't understand how you got those values :confused:
What ratio are you using? :confused:

LeRoy.
Dec 15th, 2006, 05:31 AM
I don't understand how you got those values :confused:
What ratio are you using? :confused:

from the chemical eqn i got the values

multiply by 2 throughout to get the second set of numbers

nbaker53
Dec 15th, 2006, 05:33 AM
from the chemical eqn i got the values

multiply by 2 throughout to get the second set of numbers

I still don't understand?
Is there anyway you could make things more simpler? :wavey:

LeRoy.
Dec 15th, 2006, 05:37 AM
CO2 +3H2 --> CH3OH + H2O

1 mol CO2 + 3 mol H2 ---> 1 mol CH3OH + 1 mol H2O

2 mol CO2 + 6 mol H2 ---> 2 mol CH3OH + 2 mol H2O

rrfnpump
Dec 15th, 2006, 05:38 AM
CO2 +3H2 --> CH3OH + H2O

you got that... you see that you need 1 mol CO2 and 3 mol H2 to get one mol Ch3OH, right? so if you you have 2 mol CO2 it would look like this :

2CO2 + 6H2 --> 2CH3OH + 2H2O

but you do not have 6 mol H2, you only have three which means it doesnt matter if you have 1 mol or two 2 CO2; as long as you only have 3 mol H2 you can only get 1 mol CH3OH out of it

nbaker53
Dec 15th, 2006, 05:40 AM
CO2 +3H2 --> CH3OH + H2O

you got that... you see that you need 1 mol CO2 and 3 mol H2 to get one mol Ch3OH, right? so if you you have 2 mol CO2 it would look like this :

2CO2 + 6H2 --> 2CH3OH + 2H2O

but you do not have 6 mol H2, you only have three which means it doesnt matter if you have 1 mol or two 2 CO2; as long as you only have 3 mol H2 you can only get 1 mol CH3OH out of it

Okay, I think I sort of get it! Thanks

Brett.
Dec 15th, 2006, 05:40 AM
i thought this thread was about how to find a chemtry between a guy and girl - Just make eye contact with other! :hearts:

nbaker53
Dec 15th, 2006, 05:46 AM
Okay, another question. Not related to moles and stuff like that:

What statement is a correct description of electron loss in this reaction?

2Al + 3S --> Al2S3

A) Each aluminium atom loses two electrons
B) Each aluminium atom loses three electrons
C) Each sulfure atom loses two electrons.
D) Each sulfure atom loses three electrons.

I know this is so basic, I just can't remember any of this! :mad:

LeRoy.
Dec 15th, 2006, 05:48 AM
Okay, another question. Not related to moles and stuff like that:

What statement is a correct description of electron loss in this reaction?

2Al + 3S --> Al2S3

A) Each aluminium atom loses two electrons
B) Each aluminium atom loses three electrons
C) Each sulfure atom loses two electrons.
D) Each sulfure atom loses three electrons.

I know this is so basic, I just can't remember any of this! :mad:

B)

LeRoy.
Dec 15th, 2006, 05:49 AM
2Al+++ plus 3S-- gives Al2S3

rrfnpump
Dec 15th, 2006, 06:01 AM
Al ---> Al(3+) + 3 e- | *2
S + 2 e- ---> S(2-) | *3
______________________

2 Al + 3 S ---> Al2S3

this means either each aluminium atom loses three elektrons or each sulfure atom gets two elektrons. so it should be B)