Chapter 4 - Acids and Redox Flashcards
What happens when an acid is dissolved in water?
When dissolved in water, it will release hydrogen ions as protons into the solution.
What is a strong acid?
Releases all of its hydrogen atoms into solution.
It completely dissociates in an aqueous solution
What is a weak acid?
Releases a small proportion of its available hydrogen atoms into the solution.
It 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?
Acid + alkali -> salt + water
What is the word equation for the neutralisation of acids with carbonates?
Carbonate + acid -> salt + water + carbon dioxide
What are the common acids?
HCl, H2SO4, HNO3, CH3COOH (ethanoic)
Metal oxides, metal hydroxides, metal carbonates, and ammonia are all classified as?
Bases
Common bases
Metal oxides: MgO, CaO, CuO
Metal carbonates: Na2CO3, CaCO3, CuCO3
Alkalis: NaOH, KOH, NH3
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 are concordant results?
Within 0.10 cm^3 of each other.
When can a mean titre be worked out?
When two or more concordant results are obtained.
When working out the mean titre, it is important to use only your accurate titres. Why?
- By repeating titres untill two agree within 0.10 cm^3, you can reject inaccurate titres
- Including all titres in the mean loses accuracy of the titration technique
When is the oxidation number zero?
For elements 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 other 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 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?
The loss of electrons.
What is reduction?
The gain of electrons.
What is oxidation in terms of oxidation number?
An increase in oxidation number.
What is reduction in terms of oxidation number?
A decrease in oxidation number.
