Answer
When 2.00 moles of $O_2$ reacts, $0.800$ mole of $H_2O$ is produced.
Work Step by Step
1. Find the mole-mole conversion factors:
$2 C_2H_2(g) + 5O_2(g) -^{\Delta}-\gt 4CO_2(g) +2 H_2O(g) + 2600 kJ$
According to the coefficients: 5 moles $O_2$ = 2 moles $H_2O$
$\frac{ 5 \space moles \space O_2}{ 2 \space moles \space H_2O}$ and $\frac{ 2 \space moles \space H_2O}{ 5 \space moles \space O_2}$
2. Use the mole-mole conversion factors to calculate the amount of equivalent $H_2O$ in moles:
$ 2.00$ moles $O_2 \times \frac{ 2 \space moles \space H_2O}{ 5 \space moles \space O_2} = 0.800$ mole $H_2O$
