Basics Flashcards
(42 cards)
what is a solvent
A solvent is a substance that dissolves an insoluble solute to form a solution
States of matter arrangements:
Regular —> randomly arranged——> randomly arranged
Movement of particles
Vibrate about a fixed position—-> move around each other —-> move quickly in all directions
Closeness of particles
Very close—-> close ——> far apart
Solute
The substance which dissolves in a liquid to form a solution
Solution
A mixture of one or more solutes dissolved in a solvent
What is a compound
A pure substance made up of TWO or more elements CHEMICALLY COMBINED
What is an element?
A substance made of atoms that all contain the SAME NUMBER OF PROTONS and cannot be split into anything simpler
What is a mixture
A combination of TWO OR MORE SUBSTANCES that are NOT chemically combined
How to carry out a PAPER CHROMATOGRAPHY
1) draw a line with a PENCIL across a piece of chromatography paper; line about 1 cm from bottom, do not use pen as ink can travel up the chromatography paper w solvent
2) put spots of the sample onto the line, and allow to dry
3) SUSPEND chromatography paper in beaker with a small amount of SOLVENT, so that the bottom of the paper touches the solvent; pencil line must remain above solvent so that the inks/colourings don’t DISSOLVE into solvent
4) place lid onto beaker; prevents evaporation of the solvent from surface of paper
5) solvent will travel up paper by CAPILLARY ACTION, and the different substances of different solubilities/ affinities will travel at different rates + seperate
6) when solvent has travelled around 1cm from the top, trace the line with a pencil line- this is the SOLVENT FRONT
7) then dry paper, so that all solvent evaporates
8) analyse chromatagram
Chromatogram conclusions:
One spot: PURE substance
More than one spot: IMPURE substances
Identical spots: SAME substance
Rf value formulae
Distance moved by centre of spot/ distance moved by solvent (from pencil line)
FILTRATION
Used to seperate an UNDISSOLVED solid from a liquid/solution
How to undergo a filtration
1) place a piece of filter paper in a filter funnel above a beaker
2) mixture is poured through, and filter paper allows small liquid particles to pass through as FILTRATE
3) solid particles are too large and will stay behind as a RESIDUE
CRYSTALLISATION?
-used to seperate a dissolved solute from a solution
How to undergo CRYSTALLISATION
1) the solution is heated in an evaporating basin , allowing solvent to evaporate, and leave behind a saturated solution
2) test solution being saturated can be tested by dipping a glass rod into the solution and seeing if crystals form
3) Saturated solution is allowed to cool slowly
4) crystals begin to form, and can be collected by filtering the solution
5) washed with cold distilled water to remove impurities + allowed to dry
Why can ionic compounds conduct electricity in liquid or molten states?
The IONS are free to move
What to NOT mention in ionic bonding
INTERMOLECULAR FORCES
SODIUM and water
-MELTS INTO A BALL
-fizzing
-disappears
-moves around on the surface
IONIC LATTICE STRUCTURE
-giant, 32, alternating i
DOT + CROSS DIAGRAMS
1) charge
2) brackets
3) show transferred electrons
COVALENT BONDING
SEFAB SPEAN
Strong electrostatic forces of attraction between a shared pair of electrons and nuclei
Why do simple molecular structures have a LOW MELTNIG POINTS
Simple molecular structures have WEAK IMF, that require LITTLE energy to break
Why do GIANT COVALENT STRUCTURES have a high melting point?
GIANT COVALENT structures have STRONG covalent bonds that require a lot of energy to break
