Final answer:
To determine the mass of hydrogen gas produced from the reaction of 8.5 g of KH with water, we use stoichiometry to calculate that 8.5 g of KH yields 0.427 grams of hydrogen gas.
Step-by-step explanation:
The question at hand is asking about the reaction of potassium hydride (KH) with water to form potassium hydroxide (KOH) and hydrogen gas (H₂). Specifically, it asks for the mass of hydrogen gas produced when 8.5 grams of potassium hydride react with water.
To solve this, we need to use stoichiometry. First, we must find the molar mass of KH and H₂ to use in our calculations. The molar mass of potassium (K) is approximately 39.10 g/mol, and that of hydrogen (H) is approximately 1.008 g/mol, giving us a molar mass for KH of 40.108 g/mol. The molar mass of H₂ is about 2.016 g/mol.
With the balanced reaction equation KH + H₂O → KOH + H₂, we can see that one mole of KH produces one mole of H₂. Using the molar mass of KH, we calculate the moles of KH in 8.5 g:
- 8.5 g KH × (1 mol KH / 40.108 g KH) = 0.212 moles of KH
Since the reaction produces one mole of H₂ for every mole of KH, there will also be 0.212 moles of hydrogen gas. We then convert moles of hydrogen gas to grams:
- 0.212 moles of H₂ × (2.016 g/mol H₂) = 0.427 g of H₂
Therefore, the mass of hydrogen gas that results from the reaction of 8.5 g of KH with water is 0.427 grams.