# Water can be formed from the stoichiometric reaction of hydrogen with oxygen: 2H_2(g) + O_2(g) + 2H_2O(g). A complete reaction of 5.0 g of O_2 with excess hydrogen produces how many grams of H_2O?

Jan 16, 2017

Your equation specifies that $32 \cdot g$ of dioxygen and $4 \cdot g$ of dihydrogen give $36 \cdot g$ of water upon reaction, so..........

#### Explanation:

$2 {H}_{2} \left(g\right) + {O}_{2} \left(g\right) \rightarrow 2 {H}_{2} O \left(g\right)$

We started with $\frac{5.0 \cdot g}{32.00 \cdot g \cdot m o {l}^{-} 1} = 0.156 \cdot m o l \text{ dioxygen}$.

Given excess dihydrogen, this molar quantity thus gives $2 \times 0.156 \cdot m o l$ water.

And thus, $2 \times 0.156 \cdot m o l \times 18.01 \cdot g \cdot m o {l}^{-} 1 \cong 6 \cdot g$ water are evolved. Is this reaction exothermic or endothermic?