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Underpinning - Coggle Diagram
Underpinning
Chemistry
Solubility and equilibrium
Polar substance dissolves polar solvents, non polar substance dissolves non polar substances
Saturated - adding solute until no more will dissolve
When materials dissolve they split into their ions
For ionic compounds they are partially soluble and reach an equilibrium of solubility, the solubility constant (K(small)s) can then be determined, it is only for a particular constant at a different time
Gravimetric - Evaporate all water from a known volume and weigh the remaining salts
Acids, bases and pH
Base
Bases react with an acid producing a salt and water
Alkalis are bases that dissolve in water
Strong bases completely dissociate in water, weak bases are partially ionised
Amphoteric substances can act as acids and bases
pH
pH = -log[H^+(aq)]
[H^+(aq)] = 10^-pH
Kw = Ionic product of water = [H^+][OH^-]
pH is a scale for expressing conc (mol L^-1) of the [H3O^+] or [H^+] ion
Acid
Acids produce H^+ ions in water
Strong acids completely dissociate while weak acids eg organic acids only partially dissociate
Equilibrium constant for dissociation is K(small)a, calculated by conc of products / conc of reactants
H^+ or H3O^+ ion makes solutions acidic
Buffer
A buffer solution resists change in pH
It has a weak acid and its salt or a weak base and its salt, the salt dissociates completely to resist change
Reactions and Redox
Oxidation is loss of electrons, reduction is gain of electrons
The oxidation number/state is determined by the charge of the ion or distribution of electrons
The tendency to oxidise or reduce ion pairs is compared to other ions using a hydrogen electrode, this can then be used to work out the standard reduction potential (+ is strongly oxidising, - is strongly reducing)
Don't forget to balance
Bonding and the Chemistry of Water
Ionic
Donating/ accepting electrons the number of electrons depends on group on periodic table/valence electrons
Forms crystal structure (high mp and bp, conducts electricity when molten or dissolved and soluble in water)
Covalent
Sharing electrons
Covalent compounds have low melting/boiling points, low solubility in water (non polar) and don't conduct electricity
Metallic
Crystalline structure (organised pattern eg repeating in rows) it has cations surrounded by a sea of delocalised electrons which hold the structure together
Water
Properties
high heat capacity
good solute (to polar molecules anyway)
high bp and mp for what it is
Solid ice floats on liquid water (because liquid water has a more dense molecular structure)
high surface tension
Covalent bond between hydrogen and oxygen, due to electronegativity dipoles are made making the molecule polar and having the ability to form hydrogen bonds with other water molecules thus increasing bp
Carbon Chemistry
Alkanes
Alkanes (methane, ethane, propane, butane) are saturated hydrocarbons, they are saturated with hydrogen and have the general formula of CnH2n+2, it's not soluble in water
boiling point increases with chain length
Cycloalkanes have a general formula of CnH2n as they form a looped carbon skeleton
Isomers have the same formula but different structure which can result in different properties (bp, mp etc) eg branched alkanes have lower boiling points
Alkenes - have a C=C functional group and a general formula of CnH2n, they are more reactive because of the double bond (unsaturated)
Alkynes have a carbon-carbon triple bond, they're unsaturated and have the general formula CnH2n-2, and are more reactive than alkenes
Additional polymerisation involves alkenes breaking double bonds and attaching to more alkenes with broken double bonds to make compounds like polythene, this is usually done under heat, pressure or a catalyst, it makes PVC which can vary in function/properties eg flexibility
Functional groups can be added to hydrocarbons to replace a H ligand: -OH alcohol (btw it's polar so it can dissolve in water), -CHO carbonyl (aldehyde or ketone), -COOH carboxyl group (can be a fatty acid if the carbon chain is long enough), Cl or other group 7 element is a halide and -NH2 is an amine (basic, can form hydrogen bonds with water molecules)
Electronegativity - the tendency of an element to attract a bonding pair of electrons (measured on the Pauling scale)
Unbalanced electronegativity can result in a partial charge, which results in polarity
Soap are made by reacting organic acid with NaOH so there's a long hydrophobic chain attached to a polar hydrophilic COO^- and a Na^+
Proteins are polyamides and are created from amino acids
Benzene is aromatic
Phosphorus is important especially for ATP
Sulfur exists in nature as H2S or R-SH in organic compounds, H2S can be oxidised to produce S, SO2, SO3 and SO4^2-
Atoms and Ions
A
Protons have charge +1 and mass of 1
Electrons have charge – 1 and mass of zero
Neutrons have charge 0 and a mass of 1
Atomic number is the number of protons in an atom
Mass number is the sum of the protons and neutrons in an atom
Isotopes have a different number of neutrons
moles = mass/ Mr
Atom
Central nucleus with protons and neutrons
Cloud of electrons
Electrons in orbits around nucleus
Structured orbits or shells
Each shell can hold a certain number of electrons in pairs
Reactions and Gas Laws
pV=nRT
Charles' law: volume of gas is directly proportional to temperature
Boyles law: the volume of a gas is inversely proportional to the pressure of the gas at constant temperature
Avogadro's law: The volume of a gas is proportional to the number of moles of gas present
Daltons law of partial pressure: The total pressure of a gas mixture is the sum of the partial pressures of the individual gases in the mixture
The solubility of a gas will increase with its partial pressure
more heat = more temp = more kinetic energy = faster particles = state change
Chemical reaction - converting a substance into a different substance
Physical reaction - same substance different state
Equilibrium is a dynamic state when there is a forward and back reaction occurring at the same rate and can occur across the water surface
Concentration = Henrys law constant x partial pressure
Physics
Dynamics, Momentum, Forces and Motion
velocity (delta v)/ time interval (delta t) = acceleration ms^-2
momentum M = mass x velocity kgms^-1
displacement (delta x)/ time interval (delta t) = speed ms^-1
Velocity has direction (vector) speed doesn't have direction (scalar) but both have magnitude
With vector addition, independent directions are used with orthogonal (statistically independent) coordinates
1st Law of Motion = a body remains in a state of rest or uniform motion in a straight line unless it is acted on by a force, F, (measured in newtons)
2nd Law of Motion = The rate of change of momentum of a body is equal to the applied force
work done = force x displacement while force acts
change in momentum/ change in time = Force = mass x (change in velocity/ change in time)
Gravitation and Energy
smaller mass and bigger separation = smaller force
W (weight) = m (mass) x g(acceleration due to gravity on Earth)
Gravitational force - an attractive force that causes objects to fall on Earth
Energy is transferred or dissipated, never created or destroyed
Potential energy = mass x acceleration due to gravity x height
Kinetic energy = 0.5 x mass x velocity^2
acceleration = (Gravitational force x mass of earth)/radius^2
Science and Measurement
Observe, create questions, try to explain with plausible answers then make testable predictions so you can then test the predictions via experimentation, observe this and question further
Measurements can ask what, when and where questions, the measurements are brought to system international (SI) unit eg temperature - kelvin, amount of substance - mole, current - ampere, luminous intensity - candela
Science is asking questions to and using methods to gain systematic and formulated knowledge and understanding
giga = x10^9, mega = x10^6, kilo = x10^3, deci = 10^-1, centi = 10^-2, milli = 10^-3, micro = x10^-6, nano = x10^-9, pico = x10^-12
Fluid Statics, Buoyancy and Settling
Gases and liquids are fluids, gases fill container and have high kinetic energy while liquids flow to the bottom of the container
hydrostatic equation = density of fluid x acceleration of gravity x depth(or height)
pressure always acts at 90 degrees to surfaces, pressure is constant at a given depth
forces on surfaces --> pressure p (N/m^2 or Pa) = force / area
Buoyant force (aka upthrust) = Density of the liquid the object is immersed in aka ρ (kg/m³) x Volume of the displaced liquid aka V (m³) x Gravitational acceleration aka g (m/s²)
Archimedes' principle states the upward buoyant force is equal to the weight of the fluid the body displaces
Fluids in motion are restricted by internal friction aka viscocity
Laminar flow is the property of fluid particles that enable them to follow smooth paths in layers, it occurs when you have low speeds, small scales and high viscosity, turbulent flow is chaotic and is in the opposite conditions and it has eddies
Rotational Motion
Rotational motion is the motion of an object around a circular path in a fixed orbit
T = 2pi / omega T is period (seconds to complete one cycle), omega is the rate of change of an angle with time and is calculated by velocity / radius. Also pi as in 3.14...
Centripetal forces are forces that make a body follow a curved path
Formula for centripetal force: F(small)c = mv^2/r the m is mass of object, v is velocity of object and r is radius of curve
Equations of Motion
Force/mass = acceleration = change in velocity/ change in time
Gravity is vertical so F = -mg
F/m=-g
F/m=-(1/density(ρ)) change in pressure/change in direction (represented by triangle x, y or z)
F/m=fv or -fu as force depends on the flow speed in the other direction
change in u, v or w / change in time =-(1/density(ρ)) change in pressure/change in direction (represented by triangle x, y or z)(+fv if direction is x, -fu if y and -g if z) + F(small)x, y or z
acceleration (change in u, v or w / change in time) = pressure gradient force (-(1/density(ρ)) change in pressure/change in direction (represented by triangle x, y or z)) + coriolis force (+fv or -fu) + gravity force (g) + other forces (+ F(small)x, y or z)
replace the change in bit at the acceleration part with d eg du/dt to make rate of change of velocity and add rate of change of pressure eg əP/əx to replace change in pressure/change in direction
equations of motion are equations that describe the behaviour of a physical system as a set of mathematical functions in terms of dynamic variables eg time and spatial coordinates
Maths
Basic Trigonometry
Hypotenuse (opposite to right angle), Opposite (opposite angle x) and Adjacent (links the right angle to angle x)
Sin=O/H Cos=A/H Tan=O/A
Pythagoras theorem A^2 + B^2 = C^2
Sine and Cosine Functions
Sine and cosine functions (a function is a set of operations) are mathematical functions eg Y = sin(X) or Y = cos(X)
Plot this on a graph and for sin you should have Y = amplitude x sin(X+phase) phase means the starting point of the wave. And as the waves have different starting points cos has the general equation of Y = sin(X+π/2)
Every 2π radius is one scale/ wave
Xo is the scale of a sine wave
Equations
Wave speed (C) = Wavelength (L)/Period (T)
frequency (f) = 1/period (T)
C=fL
angular frequency (ω) = (2 x π)/T
Y = amplitude (A) x sin(((2 x π x X)/wavelength) - ((2 x π x t)/wave period) + phase (ɸ)) For cosine just change the sin for cos
wavenumber (k) = (2 x π)/ L
C = ω/k
Y = A x sin(kX - ωt + ɸ)
Growth and Decay Functions
Exponential growth - when the value of a power of an integer increases resulting in rapid growth Y=B^p
Exponential decay - when a negative power increases Y=B^-p
General growth/decay function Y = Yo (initial value aka when X=0) x base number ^(growth/decay coefficient x X)
ln on the calculator is log(small e)(Y)
Powers
a^m x a^n = a^(m+n)
a^0 = 1
a^m / a^n = a^(m-n)
(a^m)^n = a^(mn)
a^-m = 1/a^m
a(m/n) = a^m under the root (surd) of n
Rates of Change
to find the rate of change at a certain point (X(small)o) we draw a slope and do change in y/ change in x, the smaller the change in x the more accurate to the point, reduce it to 0 and use this equation: slope = limit {(y(X(small)o + change in X) - Y(X(small)o)) / change in X} this equation is written as dY/dX (it means rate of change of position Y with respect to position X, this equation can also be written as d/dX (Y) it means the same thing), if there's multiple quantities that effect it the curly upside down e (ə) is used instead of the d
