Principles of Chemistry Flashcards
Name the processes responsible for the change of state from solid to gas
sublimation
Name the processes responsible for the change of state from gas to solid
deposition
What is diffusion
the net movement of particles from an area of high concentration to an area of low concentration - down a concentration gradient until an equillibrium is reached
What is a solubility curve?
a curve which shows how the solubility of a substance (in g per 100g of water) changes with temperature
What is an atom?
the smallest particle of a chemical element that can exist
What is an element?
a substance made up of only one type of atom
What are compounds?
two or more elements chemically combined in fixed proportions
What is a mixture?
two or more elements not chemically combined
What are 5 methods which mixtures can be separated?
filtration, evaporation/crystallisation, simple distillation, fractional distillation, chromatograhy
Describe and explain simple distillation
used to seperate liquid from a solution
the liquid boils off and condenses in a condenser
able to keep liquid (collected in separate beaker)
Describe and explain evaporation/crystallisation
a technique used for the seperation of a solid dissolved in a solvent
solution heated until all solvent evaporates
Crystallisation involves only removing some of the solvent by evaporation to form a saturated solution which allows the solids to crystallise
Crystals can be collected and seperated from the solvent via filtration
Describe and explain fractional distillation
a technique for separation of a mixture of liquids
works when the liquids have different boiling points
uses a fractionating column
Describe and explain filtration
used to seperate an insoluble solid suspended in a liquid
residue caught in filter paper (insoluble solid)
paticles too big to fit through the holes in the paper
Describe and explain chromatography
used to seperate a mixture of substances dissolved in a solvent
How do you calculate the Rf value?
distance moved by the solute/distance moved by solvent
What is an isotope?
atoms with the same number of protons and electrons but a different number of neutrons
What is ionic bonding?
the transfer of electrons from a metal atom to a non-metal atom to form positve and negative ions
What is an ionic bond?
the relatively strong electrostatic attraction between the positve and negative ions
What are the properties of ionic substances?
high melting and boiling points
do not conduct electricity when solid
conduct when molten or dissolved in water
What is a covalent bond?
a shared pair of electrons between two atoms
What is metallic bonding?
forces of attraciton between delocalised electrons and nuclei of metal ions
What is the law of conservation of mass?
no atoms are lost or made during a chemical reaction
the mass of products=the mass of reactants
What is the formula that links mass, molecular mass and moles together?
Moles = Mass / Mr
What are the two formula that links concentration, mole/mass and volume together?
concentration = mass/volume concentration = moles/volume
What is titration?
a technique for finding the concentration of a solution by reacting a known volume of this solution with a solution of known concentration
What is the equation for % yield?
= (actual mass of product / maximum theoretical mass of product) * 100
What is electrolysis?
the passing of an electric current thorugh ionic substances that are molten or in solution to break them down into elements
What is an electrolyte?
the liquid/solution which conducts electricity
What is a cathode and an anode?
cathode = negative electrode anode = positive electrode
What occurs at the cathode and anodes?
reduction and oxidation
