One type of portable hydrogen generator uses calcium hydride to produce hydrogen
ID: 497437 • Letter: O
Question
One type of portable hydrogen generator uses calcium hydride to produce hydrogen gas: CaH2_(s) + 2H_2O rightarrow Ca(OH)_2 + 2H_2(g) What mass of water is needed to react with a 65.0 g cartridge of calcium hydride (CaH_2)? (Done stepwise, assuming the equation is balanced and you have the molar masses) Determine the moles of CaH_2 in a 65.0 g cartridge Determine how many moles of water would be needed Determine the mass of the water needed What mass of hydrogen gas would be produced from a 75.0 g cartridge of calcium hydride (CaH_2)? (Do stepwise or run calculations together)Explanation / Answer
Ans. #1. Step 1: Moles of CaH2 in 65.0 g cartridge =
(Mass of CaH2 / Molar mass of CaH2)
= 65.0 g/ (42.0 g/ mol)
= 1.548 mol
Step 2: According to the stoichiometry of balanced reaction, 1 mol CaH2 reacts with 2 mol H2O.
So, number of moles of H2O required = 2 x moles of CaH2
= 2 x 1.548 mol
= 3.096 mol
Step 3: Mass of H2O required = Moles of H2O required x its Molar mass
= 3.096 mol x (18.0 g/ mol)
= 55.728 g
= 55.7 g
Ans. #2. Step 1: Moles of CaH2 in 75.0 g cartridge =
(Mass of CaH2 / Molar mass of CaH2)
= 75.0 g/ (42.0 g/ mol)
= 1.786 mol
Step 2: According to the stoichiometry of balanced reaction, 1 mol CaH2 reacts with 2 mol H2O.
So, number of moles of H2O required = 2 x moles of CaH2
= 2 x 1.786 mol
= 3.572 mol
Step 3: Mass of H2O required = Moles of H2O required x its Molar mass
= 3.572 mol x (18.0 g/ mol)
= 64.296 g
= 64.3g
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