5. Chemical Reactions & Stoichiometry Flashcards
1
Q
Chemical Reaction
A
- reactants –> products
- chemical bonds between atoms in the reactants are broken and new bonds are formed in different combinations to form products
2
Q
Decomposition
A
- chemical reaction whereby larger reactants are broken down into smaller products
AB –> A + B
3
Q
Catabolism
A
- particular form of decomposition
- biochemical process of breaking down molecules to supply energy
proteins–> amino acids
proteins –> glucose
glycogen –> glucose
triglycerides –> fatty acids
4
Q
Combination
A
- chemical reaction whereby smaller reactants combine to form larger products
A + B –> AB
5
Q
Anabolism
A
- particular form of combination reaction
- biochemical process of building larger molecules from smaller ones, such as the synthesis of stuctural components of cells and tissues
6
Q
Single Replacement Reaction
A
- involves two reactants and two products, whereby an atom or molecule within a compound is replaced by another atom or molecule
AB + C –> AC + B
7
Q
Double Replacement Reaction
A
- involves two reactants and two products, whereby two substances exchange parts with one another to form two different substances
AB + CD –> AC + BD
- ‘partner switching’
8
Q
Dissociation
A
- ionic compounds dissolve in water to form separate positive and negative ions
9
Q
Aqueuos Solution
A
- solution in which the solvent is water
10
Q
Spectator Ions
A
- an ion that appears unchanged on both sides of a chemical equation
11
Q
Net Ionic Equation
A
- chemical equation that does not show spectator ions
12
Q
Ions in solution react with each other when either:
A
- two ions form a solid that is insoluble in water
- two ions form a gas
- an acid neutralizes a base to form water
- one ion oxidises another
13
Q
Redox Reaction
A
- oxidation - reduction reaction which involves the transfer of electrons from one species to another
- oxidation and reduction are complimentary processes ie. one cannot occur without the other
14
Q
Oxidation
A
- loss of electrons
- gain of oxygen atoms and/or the loss of hydrogen atoms
15
Q
Reduction
A
- gain of electrons
- loss of oxygen atoms and/or the gain of hydrogen atoms
16
Q
Oxidising Agent
A
- entity that accepts electrons in a redox reaction
- substance that is reduced
- chemical species which causes another species to undergo oxidation
17
Q
Reducing Agent
A
- entity that donates electrons in a redox reaction
- substance that is oxidised
- chemical species which causes another species to undergo reduction
18
Q
Combustion
A
- particular type of redox reaction involving the production of heat and light
19
Q
Respiration
A
- particular type of redox reaction equivalent to combustion, except that it takes place more slowly + at a much lower temperature
- humans + animals acquire energy by respiration by oxidising carbon-containing componds in cells with the air breathed to produce carbon dioxide, water + energy
20
Q
Rusting
A
- iron is oxidised to a mixture of iron oxides
21
Q
Bleaching
A
- common bleaches are oxidising agents
- coloured compounds being bleached are usually organic + are converted to colourless compounds by oxidation
22
Q
Voltaic Cells
A
- device in which electricity is generated from a chemical reaction
- also known as a battery
- electrons produced at the negative electrode (anode) are consumed at the positively charged electrode (cathode)
23
Q
Heat of Reaction
A
- heat given off or absorbed during a chemical reaction
24
Q
Exothermic
A
- reaction that gives off heat
25
Q
Endothermic
A
- reaction that absorbs heat
26
Q
Heat of Combustion
A
- heat given off in a combustion reaction
- all combustions are exothermic
27
Q
Exergonic Reactions………..
A
……….generate energy
28
Q
Endergonic Reactions……….
A
……….absorb energy
29
Q
Free Energy
A
- the chemical energy of a substance
30
Q
Side Reaction
A
- secondary or subsidiary reaction that takes place simultaneously with the reaction of primary interest
31
Q
Stoichiometry
A
- term that applies to the quantative aspects of chemical composition + chemical reactions
32
Q
Formula Weight
A
- sum of the atomic weights of all the atoms in one formula unit
33
Q
Molecular Weight
A
- sum of the atomic weights of all the atoms in a molecule
34
Q
Mole
A
- quantity of a substance whose mass in grams is numerically equal to the substances formula weight
35
Q
Avogadro’s number
A
- 6.02 x 1023
- number of formula units per mole
36
Q
Molar Mass
A
- mass of one mole of a substance expressed in grams
- formula weight of a compound expressed in grams
37
Q
Limiting Reagent
A
- reactant that is consumed leaving an excess of another reagent or reagents unreacted
38
Q
Actual Yield
A
- mass of product actually obtained from a particular chemical reaction
39
Q
Theoretical Yield
A
- maximum amount of product that could be obtained from a particular mixture of reactants
40
Q
Percent Yield
A
% yield = (actual yield / theoretical yield) x 100
41
Q
Oxidation State (Number)
A
- indicates the number of electrons lost, gained or shared as a result of chemical bonding
- change in oxidation state of a species indicates whether it has undergone oxidation or reduction
- oxidation involves an increase in oxidation number
- reduction involves a decrease in oxidation number ie. reduction of charge
- the more electronegative element in a substance will have a negative oxidation number, while the less electronegative element will have a positive oxidation number
- alkali metals are always +1
- alkaline earth metals are always +2
- oxygen is -2, for peroxides -1 and F2O +2
- flourine is always -1
- chlorine is -1, except with O or F
- hydrogen is +1, except with metal hydrides where it is -1
