Answer:
D) 8.40 L H₂O(g).
Explanation:
- The balanced equation for the mentioned reaction is:
<em>2N₂H₄(l) + O₂(g) → N₂(g) + 2H₂O(g),
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It is clear that 2.0 moles of N₂H₄ react with 1.0 mole of O₂ to produce 2.0 moles of N₂ and 2.0 moles of H₂O.
- At STP, 4.20L of O₂ reacts with N₂H₄:
It is known that at STP: every 1.0 mol of any gas occupies 22.4 L.
<u>using cross multiplication:
</u>
1.0 mol of O₂ represents → 22.4 L.
??? mol of O₂ represents → 4.2 L.
∴ 4.2 L of O₂ represents = (1.0 mol)(4.2 L)/(22.4 L) = 0.1875 mol.
- To find the no. of moles of H₂O produced:
Using cross multiplication:
1.0 mol of O₂ produce → 2.0 mol of H₂O, from stichiometry.
0.1875 mol of O₂ produce → ??? mol of H₂O.
∴ The no. of moles of H₂O = (2.0 mol)(0.1875 mol)/(1.0 mol) = 3.75 mol.
- Again, using cross multiplication:
1.0 mol of H₂O represents → 22.4 L, at STP.
3.75 mol of H₂O represents → ??? L.
<em>∴ The no. of liters of water vapor will be produced </em>= (3.75 mol)(22.4 L)/(1.0 mol) = <em>8.4 L.</em>
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<em>So, the right choice is: D) 8.40 L H₂O(g).</em>
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