C6.2- Organic chemistry (homologous series) Flashcards
c6.2.1 - c6.2.4 (alkanes, alkenes, alcohol, carboxylic acids)
define an alkane
a compound which contains only hydrogen and carbon atoms (bonded together by single covalent bonds)
acronym to remember first 5 members of alkane/alkene/alcohol/carboxylic acid series
M y E lephant P umps B alloons P ainlessly Monkeys Eat Peanut Butter Meth- eth- prop- but- pent-
what is the molecular formula for an alkane?
C H
n 2n+2
draw out the displayed formula for propane
H H H | | | H-C-C-C-H | | | H H H
why are alkanes described as saturated hydrocarbons
- they are joined by single covalent bonds
- and each carbon atom is bonded to 4 other atoms
write out the word equation for complete combustion of alkanes
alkane + oxygen -> water + carbon dioxidef
how do alkanes combust in a poor supply in oxygen? (write out the word equation)
alkane + oxygen -> carbon monoxide + carbon + water
define an alkene
an unsaturated hydrocarbon made of ONLY hydrogen and carbon atoms, which contain one double carbon carbon covalent bond
what is the molecular formula for alkenes?
C H
n 2n
draw out the displayed formula for butene
H H H H | | | | H-C-C=C-C-H | | H H
C4H8
what is different about the first 4 alkene molecules compared to alkanes?
- there is no methane
- as 2 carbon atoms must be present for a double carbon molecule to be formed
- to produce an alkane
how do alkenes react with plentiful oxygen?
alkene + oxygen -> carbon dioxide + water
SAME AS ALKANE
how do alkenes combust with a limited supply of oxygen?
alkene + oxygen -> carbon monoxide + carbon + water
SAME AS ALKANE
define a functional group
atom, or group of atoms, or type of bond in a molecule that is responsible for the characteristic reactions of the substance
what allows alkenes to undergo a wider range of reactions?
a double carbon bond functional group
what are addition reactions, and give two examples of them
- when an atom/group of atoms combine with a molecule to form a larger molecule (with NO OTHER PRODUCT)
- reaction with alkenes + bromine water
- reaction with alkenes + hydrogen
what can the addition reaction between bromine water and alkenes be used to detect?
- test for unsaturation (ie. whether hydrocarbon is an alkene or not)
describe how the addition reaction with bromine-water works (not in terms of bonds)
- bromine turns colourless with alkenes
- stays orange-brown with alkanes
- bromine reacts with alkenes, no reaction with alkanes
describe what happens when hydrogen reacts with an alkene, and what the name for that type of reaction is
- called an addition reaction
- an alkane is formed