Consider the following system at equilibrium.
CaCO3(s) mc032-1.jpg Ca2+(aq) + CO32–(aq)
The addition of which compound will cause a shift in equilibrium because of a common ion effect?
CCl4
CO2
CuSO4
Na2CO3
Na2CO3 => 2(Na^+) + 1(CO3^-2)
The CO3^-2 is the common ion and addition of more CO3^-2 will overload the PRODUCT side causing the equilibrium to shift left to remove the excess and re-establish a new equilibrium.
The addition of compound Na2CO3 will cause a shift in equilibrium because of a common ion effect.
To determine which compound will cause a shift in equilibrium due to the common ion effect, we need to identify the ions that are already present in the system and find a compound that introduces the common ion.
In this case, the system is at equilibrium with Ca2+ and CO32- ions already present. To shift the equilibrium due to the common ion effect, we need to introduce a compound that contains either Ca2+ or CO32- ions.
Looking at the options given:
1. CCl4 does not contain Ca2+ or CO32- ions.
2. CO2 does not contain Ca2+ or CO32- ions.
3. CuSO4 contains Cu2+ and SO42- ions, but does not introduce Ca2+ or CO32- ions.
4. Na2CO3 contains Na+ and CO32- ions, and adding this compound will introduce additional CO32- ions into the system.
Therefore, the correct compound that will cause a shift in equilibrium due to the common ion effect is Na2CO3.