Water study notes chemistry Essays

Submitted By swaglorde
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Chapter 10: Water on Earth
Only substance found in 3 states
In BIOsphere, LITHOsphere, HYDROsphere, ATMOsphere
Essential – transport system (eg. Minerals, vitamins) - heat transfer systems - essential chemical in many reactions (eg. Photosynthesis)
Solutions
Homogenous mixtures
Solute – solid which is dissolved
Solvent – substance which does the dissolving
Saturated – no more solute will dissolve in current conditions
Unsaturated – more solute is able to be dissolved in current conditions / does not contain maximum amount of solute

Density = m / V

Chapter 11: Molecular Structure (of water) + Hydrogen Bonding
Molecular Shapes electron pairs arranged as far apart as possible = minimise repulsion
Linear

Can be Polar, eg. HCl
Can be Non-Polar eg. H2

Non-Polar
Triangular Planar
(triangle with central atom)

Bent Shaped

Polar eg. H2O
Tetrahedral
(triangular pyramid, with central atom)

Polar Bonds – covalent, uneven charge distribution
Electronegativity
determines bond type large different = ionic moderate difference = polar covalent no difference = non-polar covalent
Polar Molecules: contain one or more polar bonds
Not symmetrical

Intermolecular Forces
Hydrogen Bonding – strong dipole-dipole between H and O, N or F
Dipole-Dipole – attraction between oppositely slightly charged ends of polar molecules
Dispersion – weakest, non-polar molecules, temporary dipoles due to constant movement of electrons, usually gases

Surface Tension – molecules at surface have an overall downwards attractive force, creates tension
Viscosity – resistance to flow
M.P/B.P of Water – higher than expected due to strong HYDROGEN bonding

Chapter 12: Water as a Solvent
Solvent Dissolves a Solute
Intermolecular forces between solvent broken
Intermolecular or Ionic bonds broken
Intermolecular between solvent + solute form
‘Like Dissolves Like’
Polar solvents dissolve polar solutes
Non-polar solvents dissolve non-polar solutes
Water = polar and ionic compounds
Solubility depends = solute molecular structure + bonding
Polar or non-polar + size of particles eg. Does water have the ‘muscle’ power to physically separate the solute particles
Ionic
Usually soluble
Eg. NaCl, CuSO4
C.M which form H bonds
Soluble
Eg. Glucose, HF
Polar + Non-Polar C.M
Slightly Soluble – solubility increases with polarity
Eg. CO2, N2
Large C.M
Insoluble
Eg. Cellulose
C.N
Insoluble

Dissociation – Ionic solid separates into ions (as dissolves)
Ionisation – C.M dissolves to form ions
Electrolyte – produces ions when dissolved = conductor solution

Chapter 13: Soluble and Insoluble Salts
Precipitation Reaction – two solutions mix, insoluble solid forms
Precipitate - solid which forms from solution of two soluble solutions

Table of Solubilities
GENERALLY SOLUBLE
EXCEPTIONS (ions)
Sodium Na+,
Potassium K+
Ammonium NH4+
Nitrates NO3-
All
Sulphates SO42-
Sr, Ba, Pb ions insoluble
Ca, Ag slightly soluble
Chloride Cl-
Ag insoluble
Pb slightly soluble
Bromine Br-
Ag insoluble
Pb slightly soluble
Iodine I-
Ag, Pb insoluble…