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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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Joelleskalembe Joelleskalembe
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7 years ago
what is the mass!
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#1
Educator
7 years ago
Balanced equation:

CaH2(s) + 2 H2O(l) => Ca(OH)2(aq) + 2 H2(g)


Moles of H2 = mass/molar mass of H2

= 4.850/2.0159 = 2.4059 mol


Moles of CaH2 = 1/2 x moles of H2

= 1/2 x 2.4059 = 1.20295 mol


Mass of CaH2 = moles x molar mass of CaH2

= 1.20295 x 42.0943

= 50.64 g
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#2
Staff Member
7 years ago
Balanced Equation is



CaH2+2H2O----Ca(OH)2+2H2





We can see from the balanced equation that



42 g of CaH2 can produce 4 g of Hydrogen



So, for 4.85 g of Hydrogen we need = 4.85 * 42 / 4 = 50.925 g
Ask another question, I may be able to help!
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#3
7 years ago
the balanced equation to this is
CaH2+2H2O----Ca(OH)2+2H2



First you need to find the moles of hydrogen gas that form, find the number of moles ofcalcium hydride it took to make that numvber of moles, and convert that to grams of calcium hydride:

Moles of hydrogen gas = 4.850 g/(2*1.008 g/mole H2) = 2.3834 moles H2
Moles of CaH2 = (2.3834 moles H2) x (1 mole CaH2/2 moles H2) = 1.1917 moles CaH2
Grams Calcium hydride = 1.937 moles x 42.094 g/mol = 50.09 grams
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