Example: serum containing na gave a signal of 4.27 mv in an atomic emission analysis. then, 5 ml of 2.08 m nacl were added to 95.0 ml of serum. the spiked serum gave a signal of 7.98 mv. find the original concentration of nat in serum.

Explanation:

It is known that,

       No. of moles = Concentration × volume

As 5 ml of 2.08 M NaCl NaS added to 95 ml of serum then,

        Total volume = (95 + 5) ml = 100 ml

Therefore, total moles of = (5 × 2.08) + (95 × x)

where,      x =  concentration of in original serum

Hence, signal obtained for this NaS = 7.8 mV

Let us assume same volume, that is, 100 ml Serum then will be (100 × x) mol.

Signal obtained for this is 4.27 mV.

Now, the ratio of signal is equal to the ratio of mole.

So,  

                           x = 0.113

Thus, we can conclude that original concentration of in Serum is 0.113.

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).