How much MnO2(s) should be added to excess HCl(aq) to obtain 295 mL of Cl2(g) at 25 °C and 765 Torr?
(MnO2 and Cl2 have a one to one ratio)
MnO2 + 4 HC l -----------------------> MnCl2 + 2 H2O + Cl2
volume = 295 mL = 0.295 L
temperature = T = 25 + 273 = 298 K
pressure = P = 765 torr = 1.007 atm
moles of Cl2 = P V / R T
= 1.007 x 0.295 / 0.0821 x 298
= 0.0121
moles of Cl2 = moles of MnO2
moles of MnO2 = 0.0121
molar mass of MnO2 = 86.93 g / mol
mass of MnO2 = 0.0121 x 86.93
= 1.06 g
mass of MnO2 needed = 1.06 g
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