def peroxideIndex (Na2S2O3_molarity, Na2S2O3_fc, Na2S2O3_volume_spent, blank_volume, sample_weight):
    """
    Funtion to calculate the peroxide index in meq/Kg
    """
    V_Na2S2O3 = Na2S2O3_volume_spent - blank_volume
    mols_Na2S2O3 = Na2S2O3_molarity * Na2S2O3_fc * V_Na2S2O3
    peroxide_index = (mols_Na2S2O3 * 1000) / sample_weight # Mols of iodine = mols_Na2S2O3 / 2; meq of peroxide = mols of iodine * 2
    return peroxide_index