chemia Flashcards
autoignition temperature
the lowest temperature of which other substances start to react with oxygen - it is exothermic and oxides of particular elements are formed
colourless liquid slightly more viscous than water
hydrogen peroxide
H2O2
uses of hydrogen peroxide
oxidiser, bleaching agent, disinfectant
reaction with hydrogen peroxide
2H2O2 → 2H2O + O2
acidic oxides molecules
CO2 , SO3 , SO2
acidic oxides reacting with bases and alkalis
CO2 + 2NaOH → Na2CO3 + H2O
Carbon dioxide + sodium hydroxide → sodium carbonate + water
physical properties of acidic oxides
oxides of non-metals
gases at room temperature
basic oxides molecules
CaO, MgO, Na2O
basic oxides react with acids
MgO + 2HCl → MgCl2 + H2O
Magnesium oxide + hydrochloric acid → magnesium chloride + water
Amphoteric oxides
physical properties of basic oxides
oxides of metals
often solid at room temperature
most are soluble in water
neutral oxides
non-metals that form oxides but show neither basic nor acidic properties
insoluble in water
neutral oxides molecules
H2O, NO (nitric oxide), CO
photosynthesis
6CO2 + 6H2O → (chlorophyll, UV) → C6H12O6 (glucose) + 6O2
applications of oxygen
O2 is essential for respiration
Used in medicine
Used in welding
Making of steel and methanol
ozone O3
Allotropic form of oxygen Important compound of the atmosphere Effect on the ozone layer Ozone is toxic Used in drinking water treatment (kills pathogens, bacteria, viruses)
colours of ozone
Higher concentrations at gaseous state : slightly blue colour, has a specific odour Liquid form : blue colour
Solid form : violet/black
what is the ozone layer good for?
protects life on Earth against harmful UV radiation
allotropes of sulphur
rhombic sulfur
monoclinic sulphur
what is an allotrope
same atomic (chemical) structure, different physical properties
sulphur burning with oxygen
S (s) + O2 (g) → SO2 (g)
product : sulphur dioxide
reaction of sulphur with iron
Fe (s) + S (s) → FeS (s)
product : iron (II) sulfide
what is sulphur concrete/ where is it used
isn’t attacked by acids → used in floors and walls in factories
that use acids
sulphur dioxide when dissolved in water
SO2 + H2O → H2SO3
product : sulphurous acid
acidic rains
when fossil fuels burn sulphur dioxide escapes into the air
acid rains wash away the nutrients that plants need, it also dissolves limestone statues
uses of sulphur dioxide (SO2)
Bleaching wool, silk and wood pulp
Manufacture of sulphuric acid
Sterilising agent (jams, dried fruits) - stops the growth of bacteria and mold
uses of hydrogen sulphide (H2S)
Treating skin diseases, rheumatism
Dyeing fur
Qualitative inorganic analysis of metal ions
raw material of the contact process
sulphur, air and water
or
sulphur dioxide, air and water
uses of sulphuric acid
Fertilisers such as ammonium sulphate Paints, pigments, dyestuffs Fibers and plastics Soaps and detergents The acid used in car batteries
diluted H2SO4 (sulphuric acid) reaction with iron
H2SO4 + Fe → FeSO4 + H2
Sulphuric acid + iron → iron (II) sulphate + hydrogen
diluted H2SO4 (sulphuric acid) reaction with copper
H2SO4 + CuO → CuSO4 + H2O
Sulphuric acid + copper (II) oxide → copper (II) sulphate + water
Concentrated sulphuric acid H2SO4 reaction with copper
Cu + 2H2SO4 → CuSO4 + SO2 + 2 H2O
Copper + sulphuric acid → copper sulphate + sulphur dioxide + water
biological importance og sulphur
a minor constituent of fats, body fluids, and skeletal minerals
a key component in most proteins since it is contained in the amino acids methionine and cysteine
