Question

Hydrogen reacts with oxygen to form only water. if 16 grams of hydrogen is mized with 16 grams of oxygen, how much water can form

Answer 1

The balanced chemical equation will tell you the molar ratios in which hydrogen and oxygen react to form water:

2H2 + O2 ----> 2H2O

Then the ratio is 2 mol of H2 react with 1 mol of O2 and form 2 mol of H2O:

2 : 1 : 2

Now convert the given data into moles:

16 grams of H2 = 16 g / 2 g/mol = 8 mol

16 grams of O2 = 16 g / 16 g/mol = 1 mol.


Then you have that the 1 mol of oxygen will react with 2 moles of hydrogen and they will form  2 mol of H2O.

And you can calculate the mass of 2 moles of H2O by multiplying by its molar weigth: 18 g/mol.

2 mol H2O * 18 g/mol = 36 grams of water.

Then, the answer is 36 grams of H2O.

 

Answer 2

The reaction is:
$2 H_{2} + O _{2} -\ \textgreater \ 2 H_{2} O$
When molecular hydrogen ( H2) and oxygen ( O2 ) is combined they form either water or hydrogen peroxide.
We have that mass of hydrogen is 16 g and mass of oxygen is 16 g. But O2 is the limiting reactant. Let`s see how much grams of hydrogen can be used for this reaction:
16 g O2 x (1 mol O2)/ (32 g O2) x ( 2 mol H2)/(1 mol O2)x (2 g H2) / (1 mol H2) = 2 g H2
Finally: 16 g + 2 g = 18 g.
Answer: C. 18 grams of water.