CIE IGCSE CHEMISTRY

Add NaOH(aq) = white ppt., soluble in excess - giving a colorless solution.

Add NH3(aq) = white ppt., insoluble in excess

2 tests for cation Al3+

Add NaOH(aq) = ammonia produced on warming

Test for cation NH4+

Add NaOH(aq) = white ppt., insoluble in excess

Add NH3(aq) = no ppt., or very slight white ppt.

2 tests for cation Ca2+

Add NaOH(aq) = green ppt., soluble in excess

Add NH3(aq) = grey-green ppt., insoluble in excess

2 tests for cation Cr3+

Add NaOH(aq) = light blue precipitate, insoluble in excess

Add NH3(aq) =light blue precipitate, soluble in excess giving dark blue solution

2 tests for cation Cu2+

Add NaOH(aq) = green ppt., insoluble in excess

Add NH3(aq) = green ppt. Insoluble in excess

2 tests for cation Fe(II)2+

Add NaOH(aq) = red-brown ppt. Insoluble in excess

Add NH3(aq) = red-brown ppt. Insoluble in excess

2 tests for cation Fe(III)3+

Add NaOH(aq) = white ppt. Soluble in excess - gives a colorless solution

Add NH3(aq) = same as above

2 tests for cation Zn2+

Add dilute acid - effervescence and CO2 produced

Test for anion (CO3)2-

Acidify with dilute nitric acid, then add aqueous silver nitrate - white ppt.

Test for anion Cl-

Acidify with dilute nitric acid, then add aqueous nitrate - cream ppt.

Test for anion Br-

Acidify with dilute nitric acid, then add aqueous silver nitrate - yellow ppt.

Test for anion I-

Add aqueous sodium hydroxide then aluminum foil and warm carefully - ammonia produced

Test for anion NO3-

Acidify and add aqueous barium nitrate - white ppt.

Test for anion (SO4)2-

Add dilute HCl acid, gently warm, test for presence of sulfur dioxide - SO2 produced will turn acidified aqueous potassium manganate (VII) from purple to colorless

Test for anion (SO3)2-

Turns damp red litmus paper blue

Test for ammonia (NH3) gas

Limewater milky

Test for carbon dioxide gas

Bleaches damp litmus paper

Test for chlorine gas (Cl2)

'Pops' with a lit splint

Test for H2 gas

Relights a glowing splint

Test for O2 gas

Turns acidified aqueous potassium manganate (VII) from purple to colorless

Test for SO2 gas

Red

Flame test for lithium ion (Li+)

Yellow

Flame test for sodium (Na+) ion

Lilac

Flame test for potassium K+ ion

Blue green

Flame test for copper (II) ion (Cu2+)

ZnS

What is the equation for zinc blende?

Solubility of the salt decreases as it cools, solid crystals start to appear.

How do crystals of soluble salts form at room temperature?

To indicate the presence of iodine

Why might starch be used in a practical?

CH3COOH

What is the formula for ethanoic acid?

Write to 1 decimal place (even if .0)

What must you always do when recording temperature in a table?

An H+ ion acceptor, pH greater than 7

What is a base?

Sulfur trioxide is bubbled into FUMING (concentrated) sulfuric acid

How is oleum made in the Contact Process?

A CAREFULLY measured quantity of distilled water is added

How is oleum changed into concentrated sulfuric acid?

Form acidic oxides, forms negatively charged ions, good electron acceptor = OXIDIZING agent

What are 2 chemical properties of non-metals?

Fermentation - yeast + plant matter in anaerobic conditions produces carbon dioxide and ethanol, which is a fuel

How can liquid fuel be obtained from plant material?

Heat until a CONSTANT mass

When boiling off all the water from a substance - how do you know when all the water is gone?

Take 100cm3 of acid, add aqueous NaOH of the SAME concentration as the acid with a burette, monitor pH with a pH meter, HY neutralized by 100cm3 of NaOH, H2Y neutralized by 200cm3 of NaOH

How can you find out if the formula of an acid is HY or H2Y (Y is a variable) with an alkaline solution?

Kills bacteria

Why is sulfur dioxide used as a food preservative?

Add a reactive but not too reactive metal (like aluminum) and hydrogen gas will be produced (lit splint = squeaky pop)

How can you prove a solution is acidic without using an indicator?

Don't contain neutrons

Why is the mass number 1 proton number 1 hydrogen atom the only atom to have an identical proton and nucleon number?

Sulphur dioxide

What is the main cause of acid rain?

Transition metal elements form colored compounds

What compounds are colored?

Molecules/ions that can react with acids and bases

What does amphoteric mean?

Neutral oxide

What type of oxide is carbon monoxide?

Oxide which aren't acidic or basic - don't react with acids or bases

What is a neutral oxide?

Alkaline

What pH are metallic oxides (basic oxides) when dissolved in water?

Aluminum oxide, chromium oxide, lead oxide

Give 3 examples of amphoteric oxides:

Crystals form because the solubility decreases as the temperature decreases.

Why do crystals form - think in terms of solubility and temperature?

WARM drying oven

What type of drying oven is necessary for the formation of crystals? (Obvious answer...)

Roast in air (heated very strongly in the blast furnace)

How is zinc sulfide converted to zinc oxide in industry?

The brightness of the bulb will be less intense - because the difference in reactivity between copper and iron is less than between copper and zinc.

What will happen to the intensity of a bulb in electrolysis if instead of having 1 copper electrode and 1 zinc electrode, the zinc electrode was replaced with an iron electrode?

Iron

What element had oxidation states of 2 and 3 only?

Definite volume and shape at given temp., increase slightly in size when heated - expansion, and decrease slightly in size when cooled - contraction

What are the properties of solids?

Fixed volume at room temp., takes shape of container, volume slightly affected by temp.

What are the properties of liquids?

No definite shape/volume, fill volume of container, volume largely affected by temp.

What are the properties of gases?

All matter is made of CONSTANTLY moving particles of varying sizes, increasing temperature increases movement, heavier particles move slower than lighter ones at a given temp.

What is the kinetic theory?

Vibrate in fixed postions, strong attraction between particles

How do the particles in a solid move?

Freedom to slide/move past each other, collide often, attraction between particles

Describe the movement of particles in liquid:

Randomly, collide less often than liquids

How can the movement of particles in a gas be described?

Sublimation

What is the process of gas changing to a solid and vice versa?

Particles gain energy, vibrate faster, expand, forces of attraction decrease, structure breaks down

Describe melting:

Evaporation occurs when there are particles in a liquid that move faster, so fast that if they are near the surface they have enough energy to escape and become a gas.

Describe evaporation in terms of the escape of more energetic molecules from the surface of a liquid:

Particles gain energy, move faster, particles at surface evaporate, forces of attraction become negligible

Describe the change from liquid to gas:

The temp. at which bubbles of gas form in the liquid

What is the boiling point of a substance?

A change in which the form or appearance changes, but no new substances are formed

What is a physical change?

Remains constant

What happens to the temperature during change of state?

A pure sample

What does a sharp melting point indicate?

The net movement of particles from high to low concentration down the concentration gradient.

Define diffusion:

Diffusion between a liquid and a gas

What is intimate mixing?

Particles move faster and collide more frequently

Why does the pressure exerted by a gas increase when pressure is increased?

the constant random movement of visible particles in a fluid, as a result of continuous collisions with molecules of the surrounding medium

What is Brownian motion?

Increased pressure = increased boiling point

How does increasing pressure affect the boiling point?

Number of protons in the nucleus of an atom

What is the atomic #?

Number of nucleons (neutrons and protons) in the nucleus of an atom

What is the mass/nucleon #?

Atoms of the same element, same # of protons, different # of neutrons, have simlar properties

What is an isotope?

Stable and unstable - RADIOISOTOPES

What are the two types of isotope?

Power in nuclear reactors, medical use - treat cancer, alpha particles in smoke detectors, beta particles to find leak in pipes

What can radioisotopes be used for?

18 max, however 8 gives a certain stability

How many electrons can the 3rd energy level hold?

They are in group 0, therefore they have a full outer shell, so they are stable and do not need to gain or lose electrons. Inert: chemically unreactive

Why are noble gases inert?

A mixture of a metal with other elements

Define alloy:

Ions are electrically charged particles formed when atoms lose or gain electrons.

What is an ion and how is it formed?

when an atom gains or loses an electron

What is ionisation?

Oppositely charged electrons attracted and bonded by electrostatic forces

What is ionic bonding?

oxidation is loss, reduction is gain (of electrons)

What is OILRIG?

Metallic and non metallic elements

What elements does ionic bonding occur between?

Giant ionic lattice - regular arrangement of alternating positive and negative ions forming noble gas configuration

What is the structure of ionic substances?

Electrostatic - ionic substances have a higher melt/boil point than simple molecular substances

What is stronger - interionic or intermolecular forces? What does this result in?

Solid at room temp., high melt/boil point, conduct when molten/in solution, many (not all) are soluble in water (polar solvents), generally insoluble in non-polar solvent

Properties of ionic substances?

Ions free to move, water molecules bond to ions - break up lattice

For the ionic substances that are water soluble, how do they dissolve?

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Define covalent bonding:

Don't conduct - no ions, volatile, generally insoluble, low melt/boil point

Features of simple molecular substances?

Generally don't conduct, not volatile, generally insoluble in polar solvents, generally soluble in non-polar solvents, high melt/boil point

Features of giant covalent substances?

IGCSE - an example is water (typically inorganic), extracurricular - contain bonds between atoms with very different electronegativities

What is a polar solvent?

IGCSE - an example is benzene (typically organic), extracurricular- contain bonds between atoms with similar electronegativities

What is a non polar solvent?

Hundreds of thousands of atoms joined together by covalent bonds

What is a macromolecule?

When an element can exist in more than 1 physical form in the same state (eg. Carbon)

What is allotropy?

Conducts electricity (1 delocalized electron), formed in a hexagonal arrangement, no bonds between layers, high melt/boil point

Graphite Features

Tetrahedral arrangement, doesn't conduct (all electrons bonded), VERY hard

Diamond Features

Glass cutter, drill bits

Uses of Diamond

Similar to diamond structure (tetrahedral) 3D structure, very hard, rigid

Describe Features of Silicon (IV) Oxide