hello,

[In an experiment, equal volumes of 0.00300 M FeCl3 and 0.00300 M of NaSCN were mixed together and reacted according to the equation:

Fe + SCN --> FeSCN
The equilibrium concentration of FeSCN was 2.10*10^-4 M. Calculate K ]]

the way i did it was set up the ice table, but i used 0.00300 M as the initial concentration for both of the reactants. however, a lab buddy told me that i have to divide 0.00300 by 2, and THAT will be the initial concentration of the reactants. but i didnt understand her explanation for why this is.
can someone kindly explain whats going on here?

thank u =)

You have 2 equal volumes of 0.00300 M, so when you add them together, the concentrations become 0.00150. So if you had 1L of each reactant, the total solution is now 2L, but the amount of moles of each reactant remain the same. Make sense?

yes i get it. thank u very much =)