Question #b226c

1 Answer
Apr 22, 2017

Answer:

#K_"sp"=1.6xx10^-9#.............

Explanation:

#5C_2O_4^(2-) + 2MnO_4^(-) + 16H^(+) rarr 2Mn^(2+) + 10CO_2(g)uarr + 8H_2O#.

So, we works out moles of #"permanganate"#:

#=0.001*mol*L^-1xx4xx10^-3L=4xx10^-6*mol#

And thus, by the stoichiometry, there were #5/2xx4xx10^-6*mol# #"calcium oxalate"#, which were dissolved in #250*mL# water under conditions of saturation, i.e. a concentration of.......

#(5/2xx4xx10^-6*mol)/(0.250*L)=4.0xx10^-5*mol*L^-1#.

But, by specification, this represented a saturated solution.

And so #K_"sp"=[Ca^(2+)][C_2O_4^(2-)]#

#=(4.0xx10^-5*mol*L^-1)^2=1.6xx10^-9#