Question

Before Mendeleev published his periodic table, Johann Döbereiner grouped similar elements into triads, in which the unknown properties of one member could be predicted by averaging known values of the properties of the others. To test this idea, predict the the melting point of Br2 from the melting points of Cl2 (–101.0°C) and I2 (113.6°C)

a. –7.2 C
b. 12.6°C
c. 6.3°C
d. 214.6°C would it be d

Answer 1

(-101 + 113.6)/2 =

Answer 2

Now I see. I had figured it out in Kelvin, so 214 was the close. Thanks