Chemistry analysis code (Python)

import statistics                                               # pre-define some functions (ignore)
import math

def apprx(x):                                                   # whenever apprx() is called
    return round(x,5-int(math.log(x)))                          # round the number to to 5 digits

list1 = [[400,0.5,400,537],[800,0.5,400,678],[1200,0.5,400,300],[400,0.25,400,680],[400,0.125,400,165],[400,0.5,800,421],[400,0.5,1200,302]]
                                                                # list of 7 lists corresponding to equations a-g;
                                                                # each in format [propanone,I2,H+,time] 7 times over

length = len(list1)                                             # number of experiment equations (to be used later)


for x in range(-10,11):                                         # for each possible combination of orders w.r.t. (e.g. x,y,z)
    for y in range(-10,11):                                     #  - set to an abritrarily large range
        for z in range(-10,11):                                 #  - only whole numbers

            k = [None]*length                                   # prepare a list for the results of each equation a-g

            for e in range (0,length):                          # try each equation
                conc_x = list1[e][0]                            # obtain concentration of propane
                conc_y = list1[e][1]                            # obtain concentration of I2
                conc_z = list1[e][2]                            # obtain concentration of H+

                rate_x = conc_x ** x                            # calculate [propanone] ^ x (rate w.r.t propanone)
                rate_y = conc_y ** y                            # calculate [I2] ^ y  (rate w.r.t I2)
                rate_z = conc_z ** z                            # calculate [H+] ^ z  (rate w.r.t H+)

                leftside = 1/list1[e][3]                        # rate α 1/time -> longer time = lower rate; left side of equation = 1/time
                rightside = rate_x*rate_y*rate_z                # product of rates (right side of equation)

                k[e] = leftside / rightside                     # rate = rates w.r.t * k --> k = rate / rates w.r.t.
                                                                # (end loop; remember value of k for this combination of x,y,z; start again with a new equation)

            kaverage = sum(k)/len(k)                            # average value of k (for this combination of x,y,z)
            error = statistics.stdev(k)                         # the standard deviation of k (for this combination of x,y,z)

            relativeerror = error/kaverage                      # relative error

            if error/kaverage < 0.5:                            # if error is smaller then 0.5 ("50%")
                print("\trel.err.", apprx(relativeerror), "\tfor values", x, y, z)
                                                                # write down values of relative error and x,y,z

                                                                # (start again with a different set of coefficients)