I have a problem like this:

CHCl3 + Cl2 = CCl4 +HCL
This is the rate table:
CHCL3 Cl2 Initial Rate
.010 .010 .0035
.020 .010 .0069
.020 .020 .0098
.040 .040 .027

They want me to find the rate constant and the rate law.

If you will calculate k for ALL trials, all come out to about 3.5 and from your data 3.5 surely is correct. The only suggestion I have is that sometimes they place an exponent at the top of the table so that all of the rates would be x 10^-5 or something like that.

However, when I try to find the rate constant I get 3.5. My book says 3.5^-.5. I don't know how they got this.

.0069= (.010)^.5(.020)=approx 3.5
but the book says 3.5M^-1/2*s-1

Also I am wondering if there are three reactants in a problem, is there any difference how it is done?

To find the rate constant and the rate law, we can use the rate equation:

Rate = k[CHCl3]^m[Cl2]^n

Where:
- Rate is the observed rate of the reaction
- k is the rate constant
- [CHCl3] and [Cl2] are the concentrations of CHCl3 and Cl2, respectively
- m and n are the orders of the reaction with respect to CHCl3 and Cl2, respectively

To determine the rate law, we need to examine the effect of changing the concentration of each reactant on the rate of the reaction.

Looking at the rate table, we can see that the initial rate doubles when the concentration of CHCl3 doubles, while the concentration of Cl2 remains constant. This suggests that the reaction is first-order with respect to CHCl3.

Similarly, when the concentration of Cl2 doubles while keeping the concentration of CHCl3 constant, the initial rate approximately doubles. This indicates that the reaction is also first-order with respect to Cl2.

Therefore, the rate law for this reaction is:

Rate = k[CHCl3]^1[Cl2]^1
Rate = k[CHCl3][Cl2]

Now, to determine the rate constant, we need to choose any set of data from the rate table and substitute the values into the rate equation. Let's choose the first set of data:

Initial Rate = 0.0035 M/s
[CHCl3] = 0.010 M
[Cl2] = 0.010 M

0.0035 M/s = k(0.010 M)(0.010 M)
0.0035 M/s = 0.001 k

Solving for k:
k = 0.0035 M/s / 0.001
k = 3.5 s^-1

Therefore, the rate constant (k) is 3.5 s^-1, and the rate law is Rate = 3.5[CHCl3][Cl2].