Principles of Chemistry Flashcards
What are the properties of solids?
- fixed shape
- fixed volume
- cannot be compressed
What are the properties of liquids?
- no fixed shape, take shape of their container
- fixed volume
- can flow
- cannot be compressed
What are the properties of gases?
- no fixed shape, take shape of their container
- no fixed volume, take up volume of their container
- can flow
- can be compressed
Describe the structure of solids.
- regular arrangement
- particles tightly packed (touching each other)
- vibrate about their fixed position
Describe the structure of liquids.
- no regular arrangement
- tightly packed particles (less than solid)
- particles further apart
- move randomly at different speeds, not far as they frequently collide with other particles
Describe the structure of gases.
- no regular arrangement
- particles move randomly at different speeds, much faster than liquids
- particles separated
solid to liquid
melting
solid to gas
sublimation
liquid to solid
freezing
liquid to gas
evaporating/boiling
gas to solid
deposition
gas to liquid
condensing
Explain changes of state in terms of the kinetic theory.
temperature of a substance increases, the average KE of particles rises, gain enough energy to overcome forces of attraction
vice-versa for temperature drop
Describe the effects of temperature on the volume of a gas.
temperature of gas increases, particles move faster and further (still randomly), increasing distance between particles, so the volume of the gas increases
Describe the effects of pressure on the volume of a gas.
- increase the pressure of a gas, volume decreases
- same number of particles, less volume.
- same number of particles will exert more collisions on the sides of the container, increasing pressure
Define diffusion.
movement of particles from an area of high concentration to an area of low concentration, until the concentrations are even throughout
State factors which affect diffusion rate.
- temperature
- concentration gradient
- molecular mass
What is a concentration gradient?
The difference in concentration of a fluid between two connected areas
What is the effect of molecular mass on rate of diffusion?
the greater the molecular mass, the slower the molecules move, decreasing RoD
Explain the dependence of rate of diffusion on molecular mass.
larger molecules carry more mass, need more KE than smaller molecules to move the same distance
What is an element?
chemical substance that cannot be broken down into simpler substances and is composed of only one type of atom
What is a compound?
substance made of two or more elements chemically bonded together
What is a mixture?
two or more chemical substances found together but not chemically bonded
Describe the properties of metals.
- good electrical and thermal conductors
- high melting and boiling points
- most are malleable
- ductile
Describe the properties of non- metals.
- good electrical and thermal insulators
- usually have low melting and boiling points
- not malleable
- not ductile
- brittle
Apparatus for the measurement of time.
stopwatch
Apparatus for the measurement of temperature.
thermometer
Apparatus for the measurement of mass.
mass balance
Apparatus for the measurement of volume.
burettes, volumetric pipettes, measuring cylinders
Burettes are used to measure…
volume
What are pipettes are used to measure?
volume
What is a solvent?
a substance that dissolves a solute
a substance that dissolves a solute
solvent
What is a solute?
a substance that is dissolved in a solvent
a substance that is dissolved in a solvent
solute
What is a solution?
a mixture of one or more solutes dissolved in a solvent
What is a saturated solution?
a solution containing the maximum concentration of a solute dissolved in the solvent at a specified temperature
What is residue?
a substance that remains after evaporation, distillation, filtration or any similar process
What is a filtrate?
a liquid or solution that has passed through a filter
Why is paper chromatography used?
to separate mixtures of soluble coloured substances, using a suitable solvent
Equation for Rf
distance travelled by substance/distance travelled by solvent
What are some examples of purification?
suitable solvent, filtration, crystallisation and distillation
Purification with a solvent:
mixtures of solid substances are separated using solvents to create a suspension that can be filtered
Filtration:
removes an insoluble solid from liquids by pouring through a filter, such as filter paper
Crystallisation:
- used to obtain solid dissolved in a solution
- as liquid part of the solution cools + becomes denser, less space for solid particles to occupy - these particles are excluded from liquid + form crystal arrangements on the side of the vessel
In which condition does crystallisation work best?
when there is a large difference between the solubilities of a given soluble solid at high and low temperatures
Distillation:
separates liquids by temporarily transforming one of the liquids into a gas
How can you assess a substance’s purity using melting and boiling point information?
Impurities within a substance alter the temperature at which the bonds between them form/break, changing melting and boiling points
In chromatography, what are the unknown substances?
solutes
What happens during paper chromatography?
- unknown substances (solutes) carried up a sheet of filter paper by a solvent
- solutes move at different rates
- spread out and are deposited at different positions along the filter paper
In paper chromatography, why do solutes move at different rates?
according to their mass and solubility
What is Rf?
retardation factor value: distance a substance travels from the reference line
How can you identify substances in chromatography?
Assuming that the Rf value of a pure substance has previously been established, Rf values of each unknown solute can be found and the substance identified by comparison
How can paper chromatography be used to separate mixtures of soluble colourless substances?
using a suitable solvent and a locating agent
What is a locating agent and what is it used for?
- chemical substance that reacts with solute(s) separated in chromatography, to produce a coloured substance
- used to identify colourless compounds separated in chromatography
Define proton number / atomic number
number of protons in the nucleus of an atom
Define mass number / nucleon number
total number of protons and neutrons in the nucleus of an atom
