Transcript STOICHIMETRY Limiting Reagents

STOICHIMETRY
Limiting Reagents
AMY MARKS
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + HCL -> MgCl2 + H2
First step?
What volume of hydrogen at STP is produced from the reaction of 50.0g
of Mg and the equivalent of 75g of HCl according to the following
equation?
Mg + HCL -> MgCl2 + H2
Balance Equation
Call Mr. Kirk
End it all now
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
CORRECT!
The balanced equation is now Mg + 2HCl -> MgCl2 + H2
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
You’re getting there…What to do now?
Find the STP
Convert grams to moles
Put given over 1
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
50.0g Mg
x
?
1
24.3g Mg
1 mol Mg
6.02x10^23
1 mol Mg
24.3g Mg
1 mol Mg
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
50.0g Mg
1
1 mol Mg
x
24.3g Mg
x
?
1 mol H2
1 mol Mg
1 mol Mg
1 mol Mg
1 mol H2
22.4 L
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
50.0g Mg
x
1
1 mol Mg
24.3g mg
x
1 mol H2
x
?
1 mol Mg
22.4 L
1 mol H2
1 mol H2
22.4 L
Just stop 
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
50.0g Mg x
1
1 mol Mg
24.3g Mg
x
1 mol H2
x
1 mol Mg
46.1 L H2
22.4 L
= ?
1 mol H2
4.61 L H2
461 L H2
You’re not done..
Continue on to 2nd half of the problem.
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
1
75g HCl
What is the first step?
1 mol
75g HCl
75g HCl
1
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
75g HCl
x
?
1
1 mol Mg
1 mol HCl
1 mol HCl
36.5g HCl
36.5g HCl
1 mol HCl
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
75g HCl
1
x
1 mol HCl x
?
36.5g HCl
2 mol HCl
__________
1 mol H2
__________
1 mol H2
__________
1 mol H2
1
2 mol HCl
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
75g HCl
1
x
1 mol HCl
36.5g HCl
x
1 mol H2
x
?
2 mol HCl
Click me
1 mol
H2
22.4 L
What volume of hydrogen at STP is produced from the reaction of
50.0g of Mg and the equivalent of 75g of HCl according to the
following equation?
Mg + 2HCl -> MgCl2 + H2
75g HCl
x
1
23.0 L H2
1 mol HCl x
1 mol H2
36.5g HCl
2 mol HCl
x
22.4 L H2
1 mol H2
23 L H2
= ?
YEAHHHH BUDDY
you’re almost done. Close enough.
Let’s go.
What is the excess reagent of the
equation?
Which do you pick?
fail
50.0g
75g
23 L
EXCESS REAGENT
cool, you got it.
Mg + 2HCl -> MgCl2 + H2
23 L H2
x
?
1
1 mol H2
22.4 L H2
22.4 L H2
1 mol H2
Who
cares.
Excess Reagent Cont..
Mg + 2HCl -> MgCl2 + H2
23L H2 x 1 mol H2 x ?
1
22.4L H2
1 mol
____
2 mol
1 mol H2
____
1 mol
Mg
1 mol
Mg
____
1 mol H2
WOOO. Got it right…
Mg + 2HCl -> MgCl2 + H2
23L H2 x 1 mol H2 x 1 mol Mg x ?
1
22.4L H2
1 mol H2
24.3 g
1 mol Mg
2 mol Mg
1 mol Mg
24.3 g
44.6 g
Almost finished!
Excess Reagent cont..
Mg + 2HCl -> MgCl2 + H2
23L H2
1
x
1 mol H2
x
22.4L H2
1 mol Mg x 24.3Mg
1 mol H2
= ?
1 mol Mg
24 g
25.0 g
25 g
In order to find the excess reagent you must now subtract the previous
total from the amount that was not the limited reagent.
What volume of hydrogen at STP is produced from the reaction of 50.0g of
Mg and the equivalent of 75g of HCl according to the following equation?
Mg + 2HCl -> MgCl2 + H2
Limited reagent : HCl
Previous total : 25g
Non limited : Mg
50.0-25 = 25.0
75-25=50
FINALLY DONE
The excess reagent is 25.0
How Depressing..
So close 
YEAHHH..no.
Sorry, but..no.
U mad?
Back to start.

Stay mad.