Answer:
a) Approximate boiling point of HBr = -60.15 °C
b) Approximate boiling point of AsH₃ = -52.25 °C
Explanation:
Döbereiner stated that some elements could be arranged in groups of 3 similar elements ( known as "triads) , and the element of the middle ( elements are ordered with respect to their atomic mass) would have properties between the other 2 ( the average value)
a) In the first case the triad would be the halogen triad ( Cl , Br and I ) . And according to Döbereiner , the boiling point of HBr should be the average of HCl and HI . Therefore
Approximate boiling point of HBr = [(- 84.9°C) + (-35.4°C)]/2 = -60.15 °C
b) Simmilarly for AsH₃ , PH₃ and SbH₃ , the boiling point of AsH₃ would be
Approximate boiling point of AsH₃ = [(- 87.4°C) + (-17.1°C)]/2 = -52.25 °C
