Question

I need help with Gas Stoichiometry. I will fan and medal.

Answer 1

Assume that 13.5 g solid aluminum (Al) react with HCl to produce solid aluminum chloride (AlCl3) salt and gaseous hydrogen (H2) at standard temperature and pressure.

Answer 2

How many moles of Al react?
How many moles of H2 are produced?
How many liters of H2 are produced?

Answer 3

write a reaction between them
and balance it

Answer 4

thats first step

Answer 5

Wouldn't it look something like this?
Al + HCl --> AlCl3 +H2

Answer 6

its not balanced.......

Answer 7

Yes I know, but this is what you would start with to begin balancing correct? (I haven't balanced reaction in a long time.)

Answer 8

2Al + 6HCl = 2AlCl3 + 3H2

Answer 9

alright now its balanced

Answer 10

moving on to next step

Answer 11

look
you are given mass of Al
can you guess what you can find using this mass?

Answer 12

The number of moles.
(By the way, I do apologize for the slow responses. My internet keeps going in and out.)

Answer 13

its okay
yeah thats right
what is the formula we use to find mole?

Answer 14

N=C X V

Answer 15

what is N, C and V?

Answer 16

grams (# of moles / molar mass of element) = # of moles

Answer 17

thats right @Catseyeglint911

Answer 18

Yay! It's reassuring to know that I haven't forgotten everything.
What next?

Answer 19

Molar mass of Al you can find from periodic table
do not forget about coefficient 2 before Al
because it means there are 2 of Al atoms
thus molar mass should be of 2 Al atoms

Answer 20

now you are given grams and you can get molar mass from periodic table
put the values into the formula
mole= mass/ Molar mass
and get the mole value for Al

Answer 21

0.5 moles of Al (if I did it right)

Answer 22

lts check
i dont have periodic table near me, so what is molar mass of 1 Al in periodic table?

Answer 23

lets*

Answer 24

1 mole = 26.98
2 moles = 53.96

Answer 25

alright good
but don't call it mole lol you'll get confused ( thats what happens to me )

Answer 26

well if u did it with 53.96 then then your answer is right

Answer 27

Okay. :)

Answer 28

good
next step
do you know about ratios?

Answer 29

Yes.

Answer 30

btw im getting 0.25 moles

Answer 31

ok they are asking for mole of H2

Answer 32

what is the ratio between Al and H2 ?

Answer 33

Hm...I wrote it like this.
13.5 (2 / 53.96)
---------
Al : H2 2:6 or 1:3

Answer 34

oh no
2Al= 53.96
mass= 13.5
mole= mass/Molar mass
mole = 13.5/53.96

Answer 35

ratio
wrong
when you need to find ratios
look at COEFFICIENT number

Answer 36

i guess you are confused?

Answer 37

ratio 2:3 (I read the wrong coefficients)

Answer 38

Sorry I tried typing a reply but my connection cut off:
Also does that mean the formula
grams (# of moles / molar mass of element) = # of moles
is wrong?

Answer 39

no

Answer 40

you are getting confused about Molar mass

Answer 41

Mole= mass/ molar mass
look
coefficient of Al is 2
this 2 means that there are 2 Al atoms
in periodic table all molar masses are given for 1 atom of that element
so if we have 2 atoms of Al that means molar mass of 1 Al *2

Answer 42

thats why total molar mass of Al in this reaction will be 53.96
and mass is given as 13.5

Answer 43

are you getting it now?

Answer 44

Yes I do

Answer 45

okay good so now u understand why its 0.25 mole right?

Answer 46

alright so the ratio is 2:3

that means
if ratio 2 --- 0.25 mole
what will it be if the ratio is 3--- X
X= 3*0.25 / 2

Answer 47

the answer you will get will be mole of H2
is it clear?

Answer 48

Yes.
0.375 mole
and yes again.

Answer 49

lol good :)
so up until now everything is clear? no questions? (because next step is a different story lol)

Answer 50

Ready. :)

Answer 51

good
question for you familiar with STP ?

Answer 52

Yes

Answer 53

22.4 L right?

Answer 54

yes

Answer 55

alright there is a formula you better memorize
Volume= number of mole* 22.4

22.4 if its STP
if its RTP then its 24

Answer 56

RTP? I can't say that I'm familiar with that.

Answer 57

RTP is room temperature and pressure
im telling this just in case
maybe you'll learn about this one later

Answer 58

anyways
so formula is
volume = mole*22.4
you got mole for H2
so put it into this formula and get the volume :)
unit of volume will be Liters

Answer 59

Oh okay.
0.375*22.4 = 8.4L

Answer 60

yup :)
thats it i guess :D

Answer 61

Um. One problem. When I submitted my answers, they all showed up as incorrect. D:

Answer 62

hmm thats weird tho

Answer 63

well unless they took the reaction differently

Answer 64

meaning not this
2Al + 6HCl --> 2AlCl3 + 3H2
but this
Al + 3HCl --> AlCl3 + 3 1/2 H2

Answer 65

im pretty sure calculation is right

Answer 66

Possibly.
On my second attempt, instead of 0.25m, 0.375m, and 8.4L, I put 0.5m, 0.75m, and 16.8L which was approved. Maybe it was the reaction difference. That's all I can think.

Answer 67

no that means reaction was same
2Al + 6HCl --> 2AlCl3 + 3H2

Answer 68

i guess i made mistake in considering coefficient of Al while taking molar mass

Answer 69

im sorry <.<

Answer 70

and thanks to you i know my mistake :)

Answer 71

No worries. :) Thank you for your help though.

Answer 72

no problem :)