2H2+ O2 -->2H2O if 7g hydrogen reacts with 36g of oxygen, how many moles of water will form? name reagent which is limiting in the reaction and give the gram amount of excess reagent which remains in the mixture
Answers
Answer:
Explanation:
Start by taking a look at the balanced chemical equation for this reaction
2
H
2(g]
+
O
2(g]
→
2
H
2
O
(l]
Notice that you have a
2
:
1
mole ratio between hydrogen gas and oxygen gas.
This means that, regardless of how many moles of oxygen gas you have, the reaction needs twice as many moles of hydrogen gas in order to proceed.
You know that you start with
10.0 g
of hydrogen gas nad
15.0 g
of oxygen. To determine how many moles of each you have, use their respective molar masses
10.0
g
⋅
1 mole H
2
2.0159
g
=
4.961 moles H
2
and
15.0
g
⋅
1 mole O
2
32.0
g
=
0.4688 moles O
2
Notice that you have quite a significant difference, way bigger than the required
2
:
1
ratio needed, between how many moles of hydrogen gas and how many moles of oxygen you have.
This means that you're dealing with a limiting reagent. How many moles of oxygen would have been needed to react with all the hydrogen?
4.961
moles H
2
⋅
1 mole O
2
2
moles H
2
=
2.4805 moles O
2
Since you don't have that many moles of oxygen, it follows that oxygen is your limiting reagent, i.e. it will determine how much hydrogen reacts and how much remains in excess.
For example, how many moles of hydrogen gas would react if you have
0.4688
moles of oxygen?
0.4688
moles O
2
⋅
2
moles H
2
1
mole O
2
=
0.9376 moles H
2
The rest of the hydrogen will be in excess.