Quis critérios foram usadps por dobereiner em sua tentava de organiza os elementos químicos?

Döbereiner grouped the known elements into triads (sets of three) so that

•The atomic mass of the middle element was approximately the average    of the other two

•The chemical properties of the middle element were between those of the other two

•The physical properties of the middle element were between those of the other two

One example of a triad is Li – Na – K.

(a)Atomic mass of Na = 23.0 u

       Average atomic mass of Li and K = (6.9 u + 39.1 u)/2 = 46.0 u/2 = 23.0 u

(b)Li reacts slowly with water. Na reacts rapidly. Potassium reacts violently.

(c)Melting point of Na = 371 °C.

       Average melting point of Li and K = (454 °C + 330 °C)/2 = 784 °C/2

       = 392 °C

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :