Acids and redox chp 4 Flashcards
definition of an acid
A substance that when dissolved in water releases hydrogen ions as protons H+
what is a strong acid
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
what is a weak acid
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
what are some examples of bases
metal oxides, metal hydroxides, metal carbonates and ammonia (NH3) are classified as bases.
what is an alkali
An alkali is a base that dissolves in water releasing hydroxide ions (OH-) into the solution.
what are the products of a neutralisation reaction with metal oxide/hydroxide and alkalis
a salt and water is formed
how is the salt formed in a neutralisation reaction
to form the salt, the hydrogen in the acid is replaced by a metal or ammonium ion to form the salt
what is an ionic equation
A chemica reaction where only the reaction ions are written (written in their ionic froms)
what is the product of a neutralisation reaction containing a carbonate
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 the standard error of a volumetric flask used to prepare a standard solution
what are the common errors found in the apparatus for a titration
what values do you use for a mean titre
-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
what do you find out from the results of a titration
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.
definition of a oxidation number
a number assigned to an element in chemical combination which represents the number of electrons lost
rules for the oxidation number of elements
- the oxidation number is always 0 for elements
^in a pure element any bonding is to atoms of the same element.
rules for the oxidation number of compounds and ions
-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
what do roman numerals mean in the names of chemicals
-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
what does oxidation mean
gain of oxygen
loss of electrons
loss of hydrogen
what is reduction
loss of oxygen
gain of hydrogen
gain of electrons
what is a Redox reaction
a reaction involving both reduction and oxidation
what is reduction and oxidation in terms of oxidation number
- reduction is a decrease in oxidation number
- oxidation number is an increase in oxidation number
what are the products of a reaction between a metal and a acid
a salt and hydrogen is formed
