Chapter 2 Flashcards
(10 cards)
What is the Arrhenius concept of Bases?
In 1887, swedish chemist Svante Arrhenius proposed that an acid is a substance that ionizes in water to produce H* ions while a base ionizes to produce OH’- IONS.
HCL <=> H* + Cl^-
NaOH <=> Na* + OH^-
What is the brownstead-lowery concept of acids and bases?
Arrhenius theory applies well to acqueous solutions but does not explain why CO2 are acidic while NH3 are basic.
J.N brownstead and T.M lowere proposed in 1923 that an acid is a proton donor whereas a base is a proton acceptor.
H
HCL + H20 -> H O + Cl H
What are the similarities between the Arrhenius theory and the 1923 B-L concept?
All acids in the 1887 Arrhenius theory are also acids in the B-L theory, but not all bases in the 1923 B-L theory are bases in Arrhenius theory, except OH.
What gas do fossil fuels release when burned?
Small amounts of sulphur and oxides of nitrogen, alongside CO2
Describe the Lewis concept of acids and bases.
Substamces like SO2 and CO2 behave like bases despite being unable to donate or accept protons. For this, in 1923, G.N lewis proposed thst a lewis base is a substance that can donate a pair of electrons to form a coordinate covalent bond whereas a lewis acid can acceot a pair to do the same. Lewis acid-base reactions refer to the bond being made between the two.
What is ph?
Negative logarithm of the molar concentration of H* ions in an aqueous solution. A pH of 7 means the solution is neutral, a pH of less than 7 indicates an acid, while more than 7 indicates its basic.
pH= -log[H*]
What is the importance of Kw?
Kw is temperature dependent. In any aw solution, it always equates to 1×10^-14 no matter what concentration oh H plus ions of negative OH ions a solution has. This means if H* increases OH must go down and vice versa.
What is an acid-base indicator?
Used to estimate pH. They are colored organic compounds that change color as an indication of pH.
List five common indicators?
Methyl re, methyl orange, mythyl violet. Thymol blue, Phenolpthalein.
What are salts?
When replaceable hydrogen atoms are replaced, salt is formed. They are ionic compounds whose first part of the name is of a metal ion and second that of a negative acid ion.
