[zuko]

Hey guys i have a problem, they give me a reaction SpCl5 -> SpCl3 + Cl2, they tell me in 1L there are 9g of SpCl5, 3g of SpCl3 and 2g of Cl2 and then are put on reactor of 2L, i tried using V1C2=V2C2 but that didnt work at all

[Corribus]

What is the question actually asking for?

Whatever it is, you need to realize that doubling the volume effectively changes the concentrations of each substance in the vessel. Assuming the equilibrium constant does not change, can you see how doubling the volume will create a non-equilibrium situation... and the reaction will shift accordingly?

If you can't, try calculating the equilibrium constant, K, based on the information given. Then double the volume and calculate Q, the reaction quotient. Is Q = K when the volume is doubled?

[zuko]

the question it's asking for the new mass found in the new equilibrium after putting the reaction in a 2L reactor

[Borek]

Hints given by Corribus still hold, why don't you try to follow them?