Question
Calgon used as a water softner, is
A.
$$N{a_2}\left[ {N{a_4}{{\left( {P{O_3}} \right)}_6}} \right]$$
B.
$$N{a_4}\left[ {N{a_2}{{\left( {P{O_3}} \right)}_6}} \right]$$
C.
$$N{a_4}\left[ {N{a_4}{{\left( {P{O_4}} \right)}_5}} \right]$$
D.
$$N{a_4}\left[ {N{a_2}{{\left( {P{O_4}} \right)}_6}} \right]$$
Answer :
$$N{a_2}\left[ {N{a_4}{{\left( {P{O_3}} \right)}_6}} \right]$$
Solution :
Sodium polymetaphosphate is used to remove the permanent hardness of water. The commercial name of sodium polymetaphosphate is calgon meaning calcium gone. The molecular formula of calgon is $$N{a_2}\left[ {N{a_4}{{\left( {P{O_3}} \right)}_6}} \right].$$