Final answer:
The mass of hydrogen gas produced from the reaction of 8.5 g of KH with water is approximately 0.218 g.
Step-by-step explanation:
To determine the mass of hydrogen gas produced, we first need to balance the equation:
2KH + 2H₂O → 2KOH + H₂
From the balanced equation, we can see that 2 moles of KH react to produce 1 mole of H₂. Using the molar mass of KH (39.1 g/mol), we can calculate the number of moles of KH in 8.5 g:
8.5 g KH * (1 mol KH / 39.1 g KH) = 0.217 mol KH
Since the mole ratio of KH to H₂ is 2:1, the number of moles of H₂ produced is half of the number of moles of KH:
0.217 mol KH * (1 mol H₂ / 2 mol KH) = 0.109 mol H₂
Finally, we can calculate the mass of H₂:
0.109 mol H₂ * (2 g H₂ / 1 mol H₂) = 0.218 g H₂
Therefore, the mass of hydrogen gas produced from the reaction is 0.218 g.