Question

Na2SO4 solution to 0.1M solution of each Ag+ , Br 2+ and Ca2+, species first precipitated is

Answer 1

ca2+ is the answer for this question

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Answer 2

The first species that forms precipitate is : BaSO4

• Given, Concentration of salts Ag+ , Ca2+ , Ba2+   =  0.1 M
• Now, we know to calculate the ease of forming precipitate we should know its Ksp value.
• As Ag+ reacts with Na2SO4 to form Ag2SO4
• Ba2+ reacts with Na2SO4 to form BaSO4
• Ca2+ reacts with Na2SO4 to form CaSO4
• Ksp for Ag2SO4 = 1.20 * 10^-5
• Ksp for CaSO4 = 4.93 * 10^-5
• Ksp for BaSO4 = 1.5 * 10^-9
• Now,
• we know, Ksp = x*y     here x is concentration of given salt and y is concentration of SO4 salt
• for Ag2SO4 :     1.20 * 10^-5 = 0.1 * y  ,     y = 1.20 * 10^ -4
• for CaSO4 :        4.93 * 10 ^-5 = 0.1 *y ,     y = 4.93 * 10^-4
• for BaSO4 :       1.5 * 10^-9 =  0.1 * y ,        y = 1.5 * 10^-8
• Now as clearly seen BaSO4 requires lower concentrations of SO4 2-.
• So ,at first BaSO4 forms precipitate.