# General Chem question Please explain

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#### ManzRDH

##### Dinene RDH, BA
10+ Year Member
15+ Year Member

Can someone explain the steps for this:

Water is formed by adding 4.0g of H2(g) to and excess of O2(g). If 27 grams of H2O are recovered what is the % yield for the rx?
A- 25%
B-50%
C-75%
D-100%
E- cannot be determined from the info

#### HuyetKiem

##### Senior Member
10+ Year Member
15+ Year Member
ManzRDH said:
Can someone explain the steps for this:

Water is formed by adding 4.0g of H2(g) to and excess of O2(g). If 27 grams of H2O are recovered what is the % yield for the rx?
A- 25%
B-50%
C-75%
D-100%
E- cannot be determined from the info

2H2 + O2 --- > 2H2O
4g of H2 would yield 36g of water

But in you case, only 27g of water are recovered. So the % yield for the rx is:
27/36 = 75%

#### ManzRDH

##### Dinene RDH, BA
10+ Year Member
15+ Year Member
HuyetKiem said:
2H2 + O2 --- > 2H2O
4g of H2 would yield 36g of water

But in you case, only 27g of water are recovered. So the % yield for the rx is:
27/36 = 75%