Acids and redox chp 4

Question 1

definition of an acid

Answer 1

A substance that when dissolved in water releases hydrogen ions as protons H+

Question 2

what is a strong acid

Answer 2

a strong acid release all its hydrogen atoms into solution as H+ ions and completely dissociates in aqueous solution

HCl is an example of a strong acid

Question 3

what is a weak acid

Answer 3

a weak acid only releases a small proportion of its available hydrogen atoms into solution as H+ ions, partially dissociates in aqueous solution

ethanoic acid is an example of a weak acid

Question 4

what are some examples of bases

Answer 4

metal oxides, metal hydroxides, metal carbonates and ammonia (NH3) are classified as bases.

Question 5

what is an alkali

Answer 5

An alkali is a base that dissolves in water releasing hydroxide ions (OH-) into the solution.

Question 6

what are the products of a neutralisation reaction with metal oxide/hydroxide and alkalis

Answer 6

a salt and water is formed

Question 7

how is the salt formed in a neutralisation reaction

Answer 7

to form the salt, the hydrogen in the acid is replaced by a metal or ammonium ion to form the salt

Question 8

what is an ionic equation

Answer 8

A chemica reaction where only the reaction ions are written (written in their ionic froms)

Question 9

what is the product of a neutralisation reaction containing a carbonate

Answer 9

salt + water + carbon dioxide

Question 10

what is a titration

Answer 10

a technique used to accurately measure the volume of one solution that reacts exactly with another solution

Question 11

what are titrations used for

Answer 11

-finding the concentration of a solution
-identification of unknown chemicals
-finding the purity of a substance

Question 12

what is the standard error of a volumetric flask used to prepare a standard solution

Answer 12

Question 13

what are the common errors found in the apparatus for a titration

Answer 13

Question 14

what values do you use for a mean titre

Answer 14

-use only your closest accurate titres
-by repeating titres until 2 agree with 0.10 cm3, you can reject inaccurate titres.
-if you include all titres in the mean accuracy could be lost

Question 15

what do you find out from the results of a titration

Answer 15

you would know the concentration and the reaction volume of one of the solutions and you would only know the reacting volume of the other solution.

Question 16

definition of a oxidation number

Answer 16

a number assigned to an element in chemical combination which represents the number of electrons lost

Question 17

rules for the oxidation number of elements

Answer 17

• the oxidation number is always 0 for elements
  ^in a pure element any bonding is to atoms of the same element.

Question 18

rules for the oxidation number of compounds and ions

Answer 18

-each atom in a compound has an oxidation number
-an oxidation number has a sign, which is placed before the number
-sum of oxidation number = total charge

Question 19

what do roman numerals mean in the names of chemicals

Answer 19

-Roman numerals are used in the names of compounds of elements that form ions with different charges. They show the oxidation state of the element

Question 20

what does oxidation mean

Answer 20

gain of oxygen
loss of electrons
loss of hydrogen

Question 21

what is reduction

Answer 21

loss of oxygen
gain of hydrogen
gain of electrons

Question 22

what is a Redox reaction

Answer 22

a reaction involving both reduction and oxidation

Question 23

what is reduction and oxidation in terms of oxidation number

Answer 23

• reduction is a decrease in oxidation number
• oxidation number is an increase in oxidation number

Question 24

what are the products of a reaction between a metal and a acid

Answer 24

a salt and hydrogen is formed