Question

element A,B and C form a doberiner's trade if the atomic mass of element A is 40.1 and that of element C is 137.3theb what is the atomic mass of element B​

Answer 1

$\bigstar$ Answer $\bigstar$

We know that,

Dobereiner law of triads:

It states that,

In ascending order of atomic masses, the arithmetic mean of the atomic masses of the first and third element will be approximately equal to the atomic mass of the second element in the triad.

(Triad = a set of three similar elements)

For Simple Understanding,

B will have a mass that will be equal to mean of the masses of other two elements in the same triad

So,

We are given three elements A , B and C where,

B is the middle element

and,

A and C are the other two elements first and last respectively

Hence,

According to the Question

⇒ The First Element is A

⇒ The Second Element is B

⇒ The Third Element is C

To Find the Mass of B

$\orange{\sf \implies Mass(B)=\dfrac{Mass(A)+Mass(C)}{2}}$

Given that,

Mass of Element A = 40.1 a.m.u

Mass of Element C = 137.3 a.m.u

Therefore,

$\blue{\sf \implies Mass(B)=\dfrac{40.1+137.3}{2} \ a.m.u}$

$\green{\sf \implies Mass(B)=\dfrac{177.4}{2} \ a.m.u}$

$\pink{\sf \implies Mass(B)=88.7 \ a.m.u}$

Hence,

The Atomic Mass of

Element B​ is 88.7 a.m.u

Where,

[a.m.u = Atomic Mass Unit}

Additional Information:

From the given data and the found data,

We can Conclude that

⇒ The First Element A is Calcium (Ca)

⇒ The Second Element B is Strontium (Sr)

⇒ The Third Element C is Barium (Br)