Calcium hydride, CaH2, reacts with water to form hydrogen gas.
CaH2(s) + 2 H2O(l) Ca(OH)2(aq) + 2 H2(g)
This reaction is sometimes used to inflate life rafts, weather balloons, and the like, where a simple, compact means of generating H2 is desired. How many grams of CaH2 are needed to generate 20.0 L of H2 gas if the pressure of H2 is 740. torr at 18°C?
How many grams of CaH2 are needed to generate 20.0 L of H2 gas if the pressure of H2 is 740 torr at 18 degrees C?
2016-03-02 4:06 am
回答 (1)
2016-03-02 4:20 am
✔ 最佳答案
For H₂ generated :PV = nRT
No. of moles of H₂, n = PV/(RT) = (740/760) × 20.0 / [0.0821 × (273 + 18)] = 0.815 mol
CaH₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + 2H₂(g)
When 2 moles of H₂ is generated, 1 mole of CaH₂ is needed.
No. of moles of CaH₂ needed = 0.815 × (1/2) = 0.4075 mol
Molar mass of CaH₂ = 40.1 + 1.0 × 2 = 43.1 g/mol
Mass of CaH₂ needed = 43.1 × 0.4075 = 17.6 g
收錄日期: 2021-04-18 14:32:43
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