def r_dis_a(k, cao, x):
    """
    rate of consumption (disappearance) of species A for HW3 prob 1
    :param k: rate coefficient at temp of interest (1/min)
    :param cao: initial concentration of A in mol/L
    :param x: conversion of A
    :return: rate in mol/L-mib
    """
    return k * cao * (1 - x)