Chapter 4 - Acids and Redox Flashcards
Acids, bases and neutralisation, Acid-base titration and Redox.
What is an acid?
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 aqueous solution.
What is a weak acid?
Releases a small proportion of its available hydrogen atoms into solution.
It partially dissociates in aqueous solution.
What is a base?
A base neutralises an acid to form a salt. + water
what are some examples of bases?
there are several types of bases
metal oxides
metal hydroxides
metal carbonates
alkalis
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
ammonia + acid = ?
ammonia ,NH3 reacts with acids by accpeting H+ to form ammonium salts containing an ammonium ion
e,g
HCL + NH3 = NH4Cl
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?
titrations are 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.
how to prepare a standard solution? 2 steps for NaOH
step 1: find mass of NaOH you want
step2:
weigh NaOH you need
dissolve NaOH, with stirring, in distilled water
pour solution into volumetric flask
rinse beaker with distilled water into the flask
add distilled water to flask - bottom of meniscus on graduation line
place stopper on flask and invert
When can a mean titre be worked out?
When two or more concordant results are obtained.
In an acid base titration, what rule is used to determine a solution’s concentration?
n(1)=n(2)
c(1)V(1)=c(2)V(2)
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.
What is the word equation for the reaction of a metal with acid?
Metal + acid -> salt + hydrogen
