For rate = k[NO]^2[Cl2], a trial with [NO] = 0.10 M and [Cl2] = 0.10 M gives 0.00300 mol/L/s. What is k?

1. Substitute into rate = k[NO]^2[Cl2] with the trial values. 2. The concentration factor is 0.10 squared times 0.10, which is 0.0010 mol^3/L^3. 3. So 0.00300 mol/L/s equals k times 0.0010 mol^3/L^3. 4. Dividing gives k = 3.0 L^2/mol^2/s. 5. The reaction is third order overall, so the units must be L^2/mol^2/s and not L/mol/s. 6. The value 0.30 comes from squaring only one concentration and forgetting the third factor. 7. The value 300 comes from dividing by 0.10 cubed written as 1.0 x 10^-5 by mistake. _Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.3 Rate Laws_