Question #57b25

1 Answer
David Drayer
Aug 20, 2017

Your answer is entirely reasonable. However your answer has too many significant digits 90.4 grams of #Mg_2Si# has only three significant digits so your answer can have only 3 significant digits
None of the answer given seem to be correct.

Explanation:

First find the number of moles of# Mg_2Si #in 90.4 grams of #Mg_2Si#

# 2 xx Mg = 2 xx 24 = 48#
# 1 xx Si = 1 xx 28 = 28# adding them gives

# 48 + 28 = 76 g/m Mg_2Si#

# 90.4/76 = 1.19 m.#

1 mole of #Mg_2Si # = 1 mole of # SiH_4#

so 1.19 moles of # Mg_2Si# = 1.19 moles #SiH_4#

# 1 Si = 1 xx 28 = 28 #
# 4 H = 4 xx 1 = 4 #

adding them gives 32 g/m # SiH_4#

# 1.19 xx 32 g/m = 38.1 g SiH_4#

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