Inorganic Chemistry Flashcards
Name the processes
responsible for the following
phase changes: solid ⇄ gas
Sublimation (s to g)
Deposition (g to s)
What is diffusion?
It is the overall movement of particles from an area of high concentration to an
area of low concentration.
E.g. a gas will diffuse through all the space it can find.
E.g. if you spray some perfume in one corner of the room, soon you will be able to
feel the smell at the other end of the room.
What is a solubility curve?
It is a curve that shows how the solubility of a substance (in grams per 100 g of
water) changes with temperature.
Outline the main assumptions of the kinetic
theory of matter.
a) Matter is made up of atoms, molecules and ions of different sizes.
b) At the same temperature, small particles move faster than large particles
c) As temperature rises, the particles have more kinetic energy and move faster
d) Solids are made up of ordered arrangement of closely packed particles
e) Liquids do not have particles arranged regularly. Particles can move around.
f) In gases, the particles are far apart. They move fast. Their motion is random.
Explain what is meant by centrifuging
It is a method for separating out particles of different densities in a substance.
It can be used to separate suspended solids (very small particles of solid) from the
liquid they are suspended in.
It is used when the particles are so small that they can’t be separated via filtration.
In a centrifuge, the sample is spun at high rates. This forces the solid particles to
settle down at the bottom of the tube. The liquid can be decanted.
What is an atom?
An atom is the smallest particle of a chemical element that can exist.
What is an element?
An element is a substance made up of only one type of atom.
How are the element listed and approximately how
many are there?
They are listed in the periodic table; there are approximately 100.
Elements can be classified into
two groups based on their
properties; what are these
groups?
Metals and non-metals
Elements may combine
through chemical reactions to
form new products; what are
these new substances called?
Compounds
What is a compound?
Two or more elements combined chemically in fixed proportions which can
be represented by formulae
Do compounds have the same properties as their
constituent elements?
No, they have different properties.
What is a mixture? Does it have the
same chemical properties as its
constituent materials?
A mixture consists of two or more elements or compounds not chemically
combined together; the constituent materials keep their own chemical
properties, but the mixture may have different chemical properties (e.g.
melting point) as a whole.
What are the methods through which mixtures
can be separated (there are five)? Do these
involve chemical reactions?
Filtration, evaporation/crystallisation, simple distillation, fractional
distillation and chromatography; they do not involve chemical reactions
Describe and explain simple
distillation.
Simple distillation is used to separate liquid from a solution – the liquid
boils off and condenses in the condenser. The thermometer will read the
boiling point of the pure liquid. Contrary to evaporation, we get to keep the
liquid (it drips and is collected into a separate beaker).
Describe and explain crystallisation/evaporation
Evaporation is a technique for separation of a solid dissolved in a solvent from a
solvent (e.g. salt from H2O).
The solution is heated until all the solvent evaporates; the solids stays in the vessel.
Crystallisation is similar, but we only remove some of the solvent by evaporation to
form a saturated solution (the one where no more solid can be dissolved). Then,
we cool down the solution. As we do it, the solid starts to crystallise, as it becomes
less soluble at lower temperatures. The crystals can be collected and separated
from the solvent via filtration.
Describe and explain
fractional distillation
Fractional distillation is a technique for separation of a mixture of liquids.
It works when liquids have different boiling points.
The apparatus is similar to the one of simple distillation apparatus, with the additional
fractionating column placed on top of the heated flask.
The fractionating column contains glass beads. It helps to separate the compounds.
In industry, mixtures are repeatedly condensed and vapourised. The column is hot at the
bottom and cold at the top. The liquids will condense at different heights of the column.
Describe and explain filtration
Filtration is used to separate an insoluble solid suspended in a liquid. The
insoluble solid (called a residue) gets caught in the filter paper, because
the particles are too big to fit through the holes in the paper.
The filtrate is the substance (liquid) that comes through the filter paper.
Apparatus: filter paper + funnel.
Describe and explain chromatography
Chromatography is used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place a piece of paper with a spot containing a mixture
in a beaker with some solvent. The bottom of the paper has to be in contact with
the solvent. The solvent level will slowly start to rise, thus separating the spot
(mixture) into few spots (components).
Describe a paper chromatography experiment
a) A start line is drawn near the bottom of the paper. The mixture is spotted on the line.
b) A beaker is filled with small amount of solvent (it cannot touch or go above the start line
when paper is placed in a beaker)
c) Paper is hung on a rod and placed in a beaker.
d) Solvent travels up the paper, thus separating the components.
e) Before solvent level reaches the end, the paper is taken out and the finish line is
marked. The paper is dried.
f) The procedure works when the components dissolve differently in the solvent. More
soluble components travel further up the paper. Less soluble components have a
stronger attraction for the paper and travel less slowly with the solvent, therefore less
further up the paper.
g) Paper is called the stationary phase - it doesn’t move. Solvent is the mobile phase.
How is Rfcalculated?
Distance moved by the spot (solute component) / distance moved by solvent.
In a paper chromatography experiment, a
compound A was found to have an Rf
value of
0.85 - what does it tell you about the compound?
It has a higher affinity for the solvent than for the paper.
What is a separating funnel?
A separatory funnel is an apparatus for separating immiscible liquids.
Two immiscible liquids of different densities will form two distinct layers in
the separatory funnel.
We can run off the bottom layer (the liquid with greater density) to a
separate vessel.
Describe the plum-pudding model
The atom is a ball of positive charge with negative electrons embedded in
it.
