Question

Heeeeelp! D:
If 63.8 grams of aluminum metal (Al) react with 72.3 grams of sulfur (S) in a synthesis reaction, how many grams of the excess reactant will be left over when the reaction is complete?
Be sure to write out the balanced equation for this reaction and to show all of your work.

Answer 1

@dan815 @texaschic101

Answer 2

I can get all the way to the part where I have to multiply Ay by the ratio, which should be 2:3, right? But when I looked this up, someone was doing it by 3/2.. I got lost there.

Answer 3

@uri @Compassionate @skullpatrol

Answer 4

@robtobey @johnweldon1993 Pleeeeeease.

Answer 5

Step 1
Find moles of both

Answer 6

you are given masses so
mole= mass/ molecular mass
and get mole of each

Answer 7

then choose which ever mole you want (i'd suggest you to choose the one that has smaller value ~_~ well its usually faster for me)
now look at the ratio between Al and S in your balanced reaction
and now using mole of one of them and ratio of both of them -find a new mole

Answer 8

if the new mole is LESS than mole that was originally given for that element in the question = that means this element is in Excess

Answer 9

which means you found the 'required mole'
so subtract mole that you found using ration from mole that was given in the question

Answer 10

resulting mole will be that Excess not used mole
so now u can find its mass
mole= mass/ molecular mass
mass= mole* molecular mass
= mole that you got by subtraction * molecular mass of that element

and get your final answer :)

Answer 11

So.. Okay. I get the process, but where you multiply one of the moles by the ration.. You can choose either one? And do you multiply it by 2/3, or 3/2?

Answer 12

yeah you can choose whichever you want because when you take one of them and if its in excess- you would get MORE mole of the other reactant meaning more than its given in the question
(i hope u r not confused, when i say you take mole of something - i mean for the ratio to find mole of the other thing- so if mole of other thing you will get LESS than its given for it in the question= that means its in Excess= which is what we want, and so this Less mole is the mole required for the reaction and the rest is Excess that is not used)

Answer 13

write a balanced reaction so that i can tell what are you going to do

Answer 14

2Al+3S-->Al2S3
Right @Somy ?

Answer 15

your balanced reaction is right, now find the available moles of each to find out which one will run out first

Answer 16

yeah good so now take whichever mole you want
if you take Al mole then it'll be like this

ratio is 2:3
so
Al mole - 2
X mole - 3

X mole= Al mole * 3 / 2
= X mole of S REQUIRED

if you take S mole

ratio 2:3
so
S mole - 3
Y mole - 2

Y mole= S mole * 2 /3
= Y mole of Al REQUIRED

so now when you get REQUIRED for Al and S, compare them with the amount given in the question
if one of these values of Al and S is LESS then amount given in the question that means that one is in Excess

Answer 17

2 Al + 3 S → Al2S3
(63.8 g Al) / (26.98154 g Al/mol) = 2.3646 mol Al
(72.3 g S) / (32.0655 g S/mol) = 2.2548 mol S
2.2548 moles of S would react completely with 2.2548 x (2/3) = 1.5032 moles of Al, but there is more Al present than that, so Al is in excess.

((2.3646 mol Al initially) - (1.5032 mol Al reacted)) x (26.98154 g Al/mol) =
23.2 g Al left over

Answer 18

@Tech1 good job you did there :) but from now on please leave solving part for the asker :)