In: Chemistry
From 50.0 mL of 10-3 M Sr(NO3)2 we will have 50*10-3 millimoles of Sr+2.
From 50.0 mL of 10-3 M Na2CO3 we will have 50*10-3 millimoles of CO32-.
Total volume after mixing = 100ml
The concentration of Sr+2 = CO32- = 50*10-3/100 = 0.0005M
[Sr+2][CO32-] = 0.0005*0.0005 = 25*10-8 = 2.5*10-7 which is greater than the Ksp value of 1.1*10-10 so precipation will occur and all the excess Sr+2 and CO32- will form precipitate such that remaining concentration of Sr+2 and CO32- is such that [Sr+2] = [CO32-] and [Sr+2][CO32-] = Ksp.
so, lets say after precipitation the new concentration of [Sr+2] = [CO32-] = s
so, s2 = Ksp = 1.1*10-10 so, s = 1.048*10-5M so, number of moles = s*volume in L = 1.048*10-6
So, the number of moles in precipitate = number of moles present before precipitation - number of moles in solution after precipatation = 50*10-6 - 1.048*10-6 = 48.95*10-6 moles
Weight of 48.95*10-6 moles of SrCO3 = 48.95*10-6*147.63 = 7.22*10-3 g