Chapter 4 - Acids and Redox Flashcards
What is an acid ?
An acid dissolves in water to release hydrogen ions into the solution
What is a strong acid ?
An acid that completely dissociates in aqueous solution
What is a weak acid ?
An acid that only partially dissociates in aqueous solution
What is the difference between a strong and weak acid ?
A strong acid completely dissociates in an aqueous solution whereas a weak acid only partially dissociates in an aqueous solution
What is a base ?
A base neutralises an acid to form a salt
What is an alkali ?
A base that dissolves in water releasing hydroxide ions into the solution
What is the word equation for the neutralisation of acids with metal oxides/hydroxides?
Metal oxide/hydroxide + acid -> salt + water
What is the word equation for the neutralisation of acids with alkalis?
Alkali + acid -> salt + water
What is the word equation for the neutralisation of acids with carbonates?
Carbonate + acid -> salt + water + carbon dioxide
What is a titration ?
A technique used to accurately measure the volume of one solution that reacts exactly with another solution
What are titrations used for ?
- Finding the concentration of a solution
- Identification of unknown chemicals
- Finding the purity of a substance
What is a standard solution ?
A standard solution is one of known concentration
What are concordant titres ?
Titres that are within 0.10 cm^3 of each other.
When can a mean titre be worked out ?
When two or more concordant results are obtained.
How do you work out the dilution factor ?
How do you work out the initial concentration ?
- DF = final volume ÷ initial volume
- Initial concentration = DF x final concentration
When is the oxidation number zero ?
For elements that are on their own or bonded to atoms of the same element
What is the common oxidation number of Oxygen ?
-2
What is the common oxidation number of Hydrogen ?
+1
What is the common oxidation number of Fluorine ?
-1
What is the common oxidation number of Na+ or K+ ?
+1
What is the common oxidation number of Mg2+ or Ca2+ ?
+2
What is the common oxidation number of halides ?
-1
In what special case can hydrogen have an oxidation number of -1?
- When in metal hydrides
- i.e. NaH or CaH(2)
In what special case, can oxygen have an oxidation number of -1?
- In peroxides
- i.e. H(2)O(2)
In what special case, can oxygen have an oxidation number of +2?
- When bonded to fluorine
- .i.e. F(2)O
In ions, what is a trick for determining oxidation numbers ?
The sum of the oxidation numbers is equal to the total charge.
What do roman numerals show ?
Roman numerals show the oxidation number of the element, without a sign
What do roman numerals mean in the use of iron(II) or iron(III)?
- Iron(II) represents Fe2+ with oxidation number +2.
- Iron(III) represents Fe3+ with oxidation number +3.
What is oxidation in terms of oxygen ?
The addition of oxygen
What is reduction in terms of oxygen ?
The removal of oxygen
What is oxidation in terms of electrons ?
The loss of electrons
What is reduction in terms of electrons ?
The gain of electrons
What is oxidation in terms of oxidation number ?
An increase in the oxidation number
What is reduction in terms of oxidation number ?
A decrease in oxidation number
What happens when dilute acids react with metals ?
They undergo redox reactions
What is the word equation for the reaction of a metal with acid ?
Metal + acid -> salt + hydrogen
