Question

.
32 :
How many gram of oxygen (O2) is required to completely react with 0.200 g of hydrogen (H.) to
yield water (H2O)? Also calculate the amount of water formed. (molecular mass H = 2, 0 = 32)
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Answer 1

Answer:

___of O2 is required to complete react with hydrogen .

molecular mass of H2O is 18

mass of of Hydrogen 1×2=2

mass of oxygen is 16.

0.2g of hydrogen

let total gram is1.0g

0.8 g of oxygen is required to completely react with hydrogen .

Answer 2

Answer:

Okay, so regarding your question’s details in the comments… No, just because the mass of  H2O  is 15 g doesn’t mean the mass of  H2  is 15 g. Remember, there’s also an  O  in a  H2O  molecule. Sorry, I misread the comment and edited this immediately after realizing that.

Water’s chemical formula is  H2O , so the molecular mass is 18.

mH2O=15 g  

MrH2O=18  

n=mMr  

n=1518  

So, the amount of water in moles is  1518  moles, or  56  moles.

Let’s pull up the formation equation of water:

H2+12O2→H2O  

As I always say: “Don’t forget to balance the reaction,” even though it has absolutely no effects to the answer in this case, since we’re only looking for  H2  and the only thing that got balanced is  O2 , but always balance it nonetheless.

As you can see, to make 1 mole of water, you’ll also need 1 mole of hydrogen. So the ratio between  nH2O  and  nH2  is  1:1 !

The molecular mass of  H2  is 2.

nH2=56  

MrH2=2  

n=mMr  

56=m2  

m=53 g  

So, the mass of  H2  that you’ll need to form 15 g of  H2O  is  53  g, or about 1.667 g.

Explanation: