[copper2sulfate]

 
Okay so I'm kind of confused with this concept and I would greatly appreciate it if someone cleared some of my queries up.
Say you have an equation such as 2NOCl --> 2NO + Cl2
The rate would be -delta[NOCl]/deltat. Yes?
But why though? Because isn't the rate also delta[Cl2]/deltat. Meaning these two expressions are the same? But they shouldn't be because -0.5delta[NOCl]/deltat = delta[Cl2]/deltat.

So what is the actual rate equation for NOCl? If I'm given a rate for the overall reaction, is it equal to -0.5delta[NOCl]/deltat or -delta[NOCl]/deltat?

Any help is greatly appreciated and I show by gratitude by thanking you in advance.
cheers.

[SugarSkull]

For a reaction:
aA   +  bB ---> cC   +   dD

where a,b,c,d = stoichoimetric coefficients of species A, B, C and D, the rate is:
Rate = -1/a(d[A])/dt)  = -1/b(dB)/dt)  =   1/c(d[C])/dt)  =   1/d(d[D])/dt)    


where d = delta, t = time.
The reaction rate is negative with respect to the reactants because they are disappearing from the reaction vessel and positive with respect to the products as they are appearing in the reaction vessel.

So the rate of the reaction you have given is:
Rate = -1/2 (d[NOCl]) =1/2 (d[NO]/dt) = 1/1 (d[Cl2])