A stock phenolphthalein solution was prepared by dissolving 0.050 g in a total volume of 100.0 ml. You place one drop (0.050 ml) of this stock solution into a flask and dilute to 100.0 ml. The measured absorbance of this diluted sample is 0.18. What is the value of molar absorptivity, ε?

the value of molar absorptivity is 229000

Explanation:

given data

phenol phthalein solution = 0.050 g

total volume = 100.0 ml

dilute = 100.0 ml

diluted sample = 0.18

solution

we get here concentration that is express as

concentration = ( mass of solute × 1000 ) ÷ ( molar mass of solute × volume of solution ) .............1

put here value

concentration =    

concentration = 0.00157 M

and here dillution equation is express as

c1 × v1 = c2 × v2   .................2

here c1 and c2 is initial and final concentration

and v1 and v2 is initial and final volume

put here value  

0.001571 × 0.050 = c2 × 100

c2 = 7.855 × M

and

now we get molar by absorbance equation that is

A = E × C ×  l   ................3

here A is absorbance and E is molar and c is absorptivity and l is path length

put here value

0.18 = E × 7.855 ×  × 1

E = 229000

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

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