The figure shows a 12.0 V battery and three initially uncharged capacitors (C1 = 6.00 μF, C2 = 12.0 μF, C3 = 18.0 μF). The switch is first thrown to the left to charge capacitor 1. Then it is thrown to the right to transfer some of the charge to capacitors 2 and 3. When equilibrium is reached, what is the charge (μC) on capacitor 2?