Question #8453e

Write and balance the equation
#2HgO(s)->2Hg(l)+O_2(g)#

Find the molar mass of #HgO# which relative atomic masses of the elements composing it are obtainable from the periodic table; i.e.,
#HgO=216.6" g/mol"#

Find the moles of #HgO#, through molar conversion using the molar mass above as the conversion factor. Ensure that the units work out and the desired unit is attained.
#=7.8cancel(gHgO)xx(1molHgO)/(216.6cancel(gHgO))#
#=0.036molHgO#

Now, find the mole #O_2# by referring to the balanced equation where the molar ratio of #HgO# and #O_2# is obtainable from; i.e.,
#=0.036cancel(molHgO)xx(1molO_2)/(2cancel(molHgO))#
#=0.018molO_2#

Then, find the volume of #O_2#. Use the formula #PV=etaRT#, but prior to it make sure variables are up to its standard units as shown;
#T="temperature"=150^oC+273=423K#
#P="pressure"=120.3kPa#
#R="gas constant"=(8.31446L*kPa)/(mol*K)#
#eta="number of moles"=0.018mol#

Plug in values to the formula and cancel units as required to obtain the desired unit. Rearrange it and isolate the required variable; the volume (V);
#PV=etaRT#
#V=(etaRT)/(P)#
#V=((0.018cancel(mol))((8.31446L*cancel(kPa))/cancel((mol*K)))(423cancel(K)))/(120.3cancel(kPa))#
#V=0.5264L~~0.53L~~530ml#