chem general Flashcards
define catalyst
material that increases reaction rate
why does acid rain react slowly with metals and with limestone
low concentration of acid/ small surface area
: so collision frequency is low
why molecules are much less reactive than atoms
molecules have strong covalent bonding between atoms // atom has high tendency to gain electrons / has incomplete electron shell
difference between ionic bonds and covalent bonds
ionic = between metallic and non-metallic elements
covalent = between non-metallic elements
why does ionic compounds have high melting point
attractive force between oppositely charged IONS // more energy required to overcome force
how protons (H+) are involved in reaciton between an acid and a base
protons transferred from acid to base
define activation energy
minimum energy for particles/reactants to react
define homologous series
same general formula // similar chemical properties
energy transfers involved in generating electrical energy from diesel fuel
chemical -> thermal // thermal -> kinetic // kinetic -> electrical
in haber process, which substance is removed from air when hydrogen burns
oxygen
in haber process, what is the purpose of iron in the reaction vessel
catalyst // speeds up reaction // lowers activation energy
how atoms are formed at the anode
__ ion s are oxidised/lose electrons
why are reactions faster at higher temp
particles have more KE // greater collision frequency // more particles have activation energy to react
electrolysis - why chlorine gas is made at the anode
chloride IONS are attracted to the anode // chloride IONS are negative
electron loss occurs at the anode // chlorine atoms combine to form chlorine molecules
why is copper a conductor of electricity
metallic bonding // has sea of electrons // which can move through the structure
describe cracking and the conditions required
large hydrocarbon molecules broken down into smaller molecules
to make alkenes
conditions : high temp, catalyst, high pressure (50 to 200 atmospheres)
how is ethanol made by fermentation
fermentation requires water // sugar // yeast // suitable temperature // reference to anaerobic respiration
define oxidising agent
substance which gives oxygen to / gains electrons
describe how aluminium is extracted from its purified ore
molten aluminium oxide contains aluminium
oxygen is made at anode
aluminium is made at cathode
structure and bonding in graphite - why is it used as a lubricant
weak forces between the layers // layers can slide over each other
what happens to unreacted nitrogen and hydrogen in the Haber process
recycled
difference in the properties of alloy stainless steel and metal iron
steel more resistant to corrosion
how metallic and non-metallic elements form ionic bonds
metal lose electrons, non-metal gain electrons
metal form positive ions, non-metal form negative ions
attraction between oppositely charged ions
properties of transition metals that are not properties of all metals
high melting point, high density, form coloured compounds, act as catalysts
