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Name: robin
Status: student
Age: 30s
Location: N/A
Country: N/A
Date: 2000


Question:
How is hydrochloric acid an arrhenius and a bronsted-lowry acid?


Replies:
Hi Robin!

By 1887, Svante Arrhenius proposed definitions for acids and bases, that somehow are still in common use today. By that definition an acid, in aqueous solution would: turn dye litmus from blue to red, react with active metals (as Zn, Fe or Sn) dissolving it and producing hydrogen gas,react with certain compounds called alkalis or bases to form water and compounds called salts. So by that definition hydrochloric acid (HCl in aqueous solution) is an acid... Arrhenius theory has been modified through the years, as the science progressed, but was useful for many years and still is used today for many aqueous solutions.

But...1920 chemists were working with solvents other than water, and experiments showed that a new theory was needed. One was suggested in 1923, at almost the same time by J.N.Bronsted (in Copenhagen) and T.M. Lowry (England) that became knew as the Bronsted-Lowry theory. By it an acid is defined as a proton donor (an H with a + charge), and a base as a proton acceptor.

All the substances that Arrehenius considered acids are also acids by that definition. So the reaction of hydrogen chloride with water has hydrogen chloride acting as a proton donor, so it is an acid... And

Thanks for asking NEWTON!

Mabel
(Dr. Mabel Rodrigues)



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