How many moles of water can be produced from the reaction of 2.0 moles of hydrogen gas is reacted with 2.5 moles of oxygen gas? 2H2(G)+O2--->2H2O(L)
a. 5.0 mole H2O
b. 2.0 mole H2O
c. 4.5 mole H2O
d. 2.5 mole H2O

B.  2 moles of water

Explanation:

The reaction expression is given as shown below:

            2H₂   +    O₂   →    2H₂O  

Number of moles of Hydrogen gas  = 2 moles

Number of moles of oxygen gas  = 2.5moles

Unknown:

Number of moles of water produced  = ?

Solution:

To solve this problem, we need to find the limiting reactant because this reactant will determine the extent of the reaction.

   From the balanced reaction expression:

   2 mole of hydrogen gas will need to combine with 1 mole of oxygen gas

   But we have been given 2.5 moles of oxygen gas

Oxygen gas is in excess and hydrogen gas is the limiting reactant.

So;

       2 moles of hydrogen gas will produce 2 moles of water

the answer is option a.