Chemistry Flashcards
What are the properties of a solid?
- Particles are closely packed in regular structures with strong bonds.
- It is the state of matter with least energy.
- It has it’s own shape.
- Moves by vibration
What is a fuel?
A chemical store that combusts to realease energy.
Describe how particles are arranged in a solid:
- Particles held closely together
- Particles vibrate around fixed positions
- aoms in a regular formation
- little energy
- cannot be compressed
Describe how particles are arranged in a gas:
- Particles are very far apart
- Particles are separated and move freely
- Fill the space available
- Most energy of all states
- Particles move around alot
- Gas particles can be compressed
How do you separate an insoluable solid from a liquid?
Filtration.
Example of an alkali?
HYDROXIDE
OH
e.g. NaOH
What are the name of the salts made by hydrochloric acid (HCl)?
Chloride salts.
e.g. HCl + NaOH →NaCl + H20
Sulphuric acid = H2SO4
Makes sulphate salts.
e.g, H2SO4 + 2NaOH → NaSO4 + 2H20
Alkali + Acid =
Salt + Water
Acid + Metal =
Salt + Hydrogen
Acid + Carbonate =
Salt + Water + CO2
What do you see when you add a metal + acid?
- Effervescence
- Fizzes and whizzes around
- Metal disappears
What is thermal decomposition?
When heat causes a compund to break down.
HAPPENS TO CARBONATES.
CaCO3 ► HEAT ► CaO + CO2
How do you prevent rust?
Galvanise = add a more reactive metal coat
e.g. zinc added over iron.
Could also:
- paint to exclude oxygen
- cover in grease/oil
- cover in plastic
The key is to exclude oxygen
Describe how particles are arranged in a liquid:
- Particles held close together but can move freely
- more energy than a solid
- less energy than a gas
- can move freely
- will take the shape of its container
- cannot be compressed
What happens to particles when state changes from a solid to a liquid?
- Particles gain more energy
- Particles move around more
- Particles spread out
What is a chemical change?
- Bonds are made or broken
- The molecule/atom/compound is changed
- often irreversible
*
What is a physical change?
- a change of state
- the molecule itself stays the same
- it is reversible
What is combustion?
- Fuel + Oxygen
- Releases energy
What is a physical property?
- Magnetic behaviour
- Strength
- Flexibility
- Conductivity
- Hard
- Rigid
- Compressible
- Dense
- Thermal conductor
- Electrical conductor
- Shiny / dull
- Transparent / translucent / opaque
- Absorbant
- Permeable
- Waterproof
How do you obtain coloured dyes?
Chromatography
How do you obtain a soluble solid from a liquid?
Distillation
What are some examples of bases?
Hydroxides - e.g. Sodium Hydroxide (NaOH)
Oxides - (Metal oxides) e.g. MgO
Carbonates - Calcium carbonate CaCO3
Nitric acid
- Makes NITRATE salts
- e.g. HNO3 + NaOH = NaNO3 + H2O
What is a compound?
- two or more element combined
What is a mixture?
- It contains two or more types of atom/molecul/compound
- e.g. Air, soil, concrete
How do you separte a mixture?
- Sieving
- Filtering
- Decanting
- Flotation
- Evaporation
- Distillatgion
- Chromatography
What is an alloy?
- A mixture of metals:
- Brass (Copper, Zinc)
- Bronze ( Copper, Tin)
- Steel ( Iron, Carbon, Nickel)
What are the properties of metallic elements?
- There are about 80 metallic elements
- Normally solid at room tempurature
- Strong
- Shiny
- Maleable
- Conduct heat and electricity
- Dense
- High melting points
- Some are magnetic
- Corrode
- React with air or water
What is the reactivity series?
- Potassium
- Aluminium
- Zinc
- Iron
- Copper
- Silver
- Tin
- Lead
- Gold
What metals were used in ancient times?
- Copper
- Silver
- Gold
What is a solution
- A mixture of a solid liquid or gas, and a liquid
What are the properties of non-metallic elements?
- There are about 20 of these
- Not stong
- Dull
- Brittle
- Not a good conductor of heat or electricity
- Not dense
- Low melting point
What are diamonds made of?
Carbon.
The strongest sustance known to man.
Where are diamonds mined.
Africa (Angola, Botswana, South Africa)
Asia (India, Russia, Indonesia)
North America (Canada, United States)
What is graphite?
A form of carbon (i.e. non metal)
Graphite conducts electricity
How are metal oxides formed?
When metal is combined chemically with oxygen.
What is neutralisation?
An acidic solution is neutralised by an appropriate amount of an alkali solution.
What indicators of acid/alkali are used?
Litmus paper:
Acid = Red / Alkali = Blue
Universal indicator:
0-14
Red -acid, Green = neutral, Purple = alkali
Why do metals tarnish?
Tarnish is normally caused by an oxide forming on the surface.
Oxidisation and reduction
Fe + CuO ► FeO + Cu
- Iron is more reactive than Copper
- Iron is oxidised
- Copper is reduced
What is displacement?
A more reactive metal displaces another from its salt
e.g. Iron + Copper Sulphate ► Iron Sulphate + Copper
How do you extract metals from their ore
- Decomposition
- Electrolisis
- Reduction
solvent & solute =
solution
As temperature goes up how does this affect solubility?
Solubility increases.
If a substance does not dissolve in water it could dissolve in what other liquids?
ethanol or propanone.
What metals are magnetic?
Tron
Cobalt
Nickel
Steel (iron + carbon)
What is the equation for respiration?
glucose + 02 ►ENERGY RELEASED►CO2 + H2O
What is the equation for photosynthesis?
CO2 + H2O ►LIGHT►sugar + O2
What is the equation for combustion?
wood/coal/oil + 02 = CO2 + H2O + ash
Natural gas and candle wax same but no ash is formed.
What are the 3 types of rock?
- Igneous (cooled lava)
- Sedimentary (small particles settling on sea and river beds)
- Metamorphic (Sedimentary rock exposed to great pressure and temperature as a result of movements in the earth’s crust.)
What are rocks?
- Composed of minerals.
- Some minerals are pure elements or compounds.
- Many minerals are impure substances.
Define an element?
An element consists of only one type of atom.
There are about 100 types of element.
Elements are arranged in the Periodic Table.
What is soil formed from?
Weathered down rocks
Humus (rotted organic material)
What is an atom?
The simplest type of particle.
There are around 100 types of atom.
What is a molecule?
A molecule is 2 or more atoms chemically bonded togther.
What are the changes of state?
Melting Boiling
⇒ ⇒
Solid Liquid Gas
Soldifying (liquid ⇒ solid)
Condensing (gas ⇒ liquid)
Sublimation (solid ⇒ gas)
Some useful temperatures:
- Absolute zero - 2370C
- Mercury melts - 390C
- Ice melts - 00C
- Human temperature - 370C
- Alcohol boils - 780C
- Water boils - 1000C
- Gold melts - 10630C
- Surface of the sun - 60000C
Decribe the water cycle?
- Water evaporates from the sea.
- When air over the sea reaches land it is forced upwards becasue land is higher trhan sea.
- Air cools, clouds form.
- pracipitation.
- Surface run off.
- Rivers fill and flow to the sea.
Effect of global warming: As seas warm the moisture carried in the air will be greater leading to increased rainfall on land.
Designing an experiment:
3 questions to answer:
- What are you changing and how?
- What are you observing?
- What do you have to keep the same to make it a fair test?
How does evaporation work?
A small amount of molecules of gas leave the surface of a liquid at all temperatures.
What is table salt made of?
Sodium chloride and a little bit of potassium chloride.
What is the test for CO2?
Turns lime water milky.
What is the test for starch?
Iodine solution turns black.
What is the test for oxygen?
Relights a glowing splint.
Waht is the test for water?
- Water turns anhydrous copper suphate from white to blue.
OR
- Cobalt chloride paper turns pink.
Properties of hydrogen:
- 75% of the universe is made up of hydrogen.
- First recognized as an eleement in 1766 by Henry Cavendish.
- Explosive - used as a fuel in the Space Shuttle
- Melting point -2590C
- Boiling point -2530C
Properties of sodium:
- Human body cannot function without it.
- 2g per day necessary for humans.
- 2.6% of the Earth’s crust by mass.
- One of the most abundant alkali metals.
Properties of calcium:
- 5th most abundant element on the Earth’s crust.
- Essential for human bones and teeth
- Average human has 1kg of calcium in their body.
- Osteoporosis - older people lose calcium and can break their bones.
- Animal shells like snail and crab are made from calcium carbonate.
Properties of gold:
- Can be found as lumps on the ground in nature.
- Largest gold nuggett ever found in the soil was called the Welcome Stranger. It was discovered in Australia and weighed 71kg.
- Used by ancient societies as it could be discovered on the surface therefore no complicated equipment required.
Propertes of carbon:
- Huge ability to form bonds with itself.
- Many compounds and allotropes.
- 10s, 100s, 1000s of carbon atoms can be joined to make complex molecules.
- Organic Chemistry just studies carbon.
Properties of iron:
- The most common element on Earth and makes up almost 100% of the inner and outer core.
- Responible for the Earth’s magnetic field.
- Haemoglobin in blood contians iron.
Properties of oxygen:
- From Greek ‘oxy genes’ meaning acid forming.
- Most abundant element on the earth surface. Present in sand and water (seas).
- Third most abundant element in the universe after hydrogen and helium.
Properties of copper:
- Used for electrical and data wiring.
- 150 kg per person of copper wiring in the developed world.
- Known copper reserves will not be big enough for the developing world to match 150kg per head.
- Copper prices rose 400% from 2010 to 2015 because of increased demand from the developing world.
- Tarantulas have blue coloured copper based blood.
What are the properties of silver?
Not very reactive.
Can be found as lumps in th ground.
Used since ancient times because it was available without using equipment.
Oxidation and reduction
- Oxidation
- Is
- Loss of electrons (OIL)
- Reduction
- Is
- Gain of electrons (RIG)
Why has salt been known by man for so much longer than other materials?
Salt is present in the sea and man has used the sea for transport for thousands of years.
They would have tasted salt in the water and seen solid salt after water had evaporated.
Why do nomads not need extra salt in their diet?
Nomad live by herding animals. Moving them from pasture to pasture.
They live mainly on animal milk and meat.
The animal meat already contains salt.
How can salt be recovered from salt water?
Evaporation.
What are the 2 main natural sources of salt?
The sea.
Salt mines (there are pockets of salt under the earth).
Is sulphur (S) a metal or a non metal?
Non metal.
What element in the air is reacting with fuels during combustion?
Oxygen.
Whay does steel have similar properties to iron?
Steel has similar properties to iron because it is an alloy of iron.
(steel = iron + carbon)
A metal statue turns from grey to red brown.
Describe the process that has occured.
The statue must be made of iron and has rusted.
(iron + oxygen + water = rust (iron oxide)).
What is the change from solid straight to gas called?
Sublimation.
Write a word equation for the extraction of iron from iron oxide by heating it with carbon in a blast furnace?
iron oxide + carbon = itron + carbon dioxide.
Bronze is an alloy of copper and tin. Explain why knowledge of chemistry will help you work out that the Bronze age came before the Iron age in prehistoric times?
Iron is higher than copper in the reactivity series so it is harder to extract.
Greater temperatures that just a simple fire are needed. Iron was only produced when furnaces creating more heat had been created.
What is the name of a chemical reaction that involves combination with oxygen?
Oxidation.
What elements does a hydrocarbon contain?
Only hydrogen and carbon.
What is the word equation for burning methane (natural gas CH4).
Methane + oxygen = Carbon dioxide + water + energy + heat and light.
What is the definition of a fossil fuel?
Fuels formed from the remains of dead plants and animals that lived millions of years ago.
Name 2 gases produced when coal burns in air?
Carbon dioxide and sulphur dioxide.
How is acid rain formed?
Carbon diooxide and suphur dioxide (by products of burnig coal) dissolve in water vapour in the air to form acids.
Which metals can be use the term ‘rust’ for?
Only iron.
Rust is iron oxide.
Needs oxygen and water to take place.
What is meant by the reactivity series of metals?
Metals are placed in order according to how well they react with oxygen, water, steam, acids.
What is the word equation for the chemcial change when copper oxide is heated with carbon?
Copper oxide + carbon = copper and carbon dioxide.
What are the key properties of non-metal oxides?
Dissolve in water to form acidic solutions
Normally a gas at room temperature.
What is the difference between a base and an alkali?
Bases are substances that react with acids and neutralise them.
They are usually metal oxides, metal hydroxides, metal carbonates or metal hydrogen carbonates.
Many bases are insoluble - they do not dissolve in water.
If a base does dissolve in water, we call it an alkali.
Iron reacts with dilute acids.
(metal + acid = salt + hydrogen)
Create a word equation for iron combined with sulphuric acid
Iron + sulphuric acid = iron sulphide + hydrogen
Fe (s) + H2SO4 (aq) → FeSO4 (aq) + H2 (g)
What is the chemical formula for sulphuric acid?
H2SO4
What is the chemical formula for hydrochloric acid?
HCl
What is the chemical formula for nitric acid?
HN03
What is the chemical formula for methane?
CH4
Explain why quartz crystals have such regular shapes?
The particles are arranged in a regular patterned structure.
What is the main compound in sand?
Silicon dioxide.
Sand is heated with magnesium powder to obtain silicon. Wreite a word equation for the reaction:
Silicon dioxide + magnesium = Magensium oxide + silicon.
What is the difference between an element and a compound?
An element is made up of one type of atom. It cannot be broken down further.
A compound is two or more elements chemically bonded.
Describe the appearance of sand containing a high proportion of iron oxide (rust)?
It will be a red brown colour.
Suggest how calcium carbonate can be removed from a sample of sand?
Acid can be added. The carbonate is dissolved. Then the mixture is washed through. The calcium carbonate will dissolve and can be washed away.
carbonate + acid = salt + water + carbon dioxide
What are the most common iron ores?
Magnetite Fe304 and hematite Fe2O3
How would you define an ore?
An ore is a natually occuring rock containing a metal in the form of a compound. compound. The componds are usually oxides.
What is the name for aluminium ore?
Bauxite.
Bauxite contains aluminium oxide.
Is gold found in an ore?
No it’s too unreactive to bond with oxygen naturally.
It tends to be found as the native metal, not
What dangerous gas smells like rotten eggs?
hydrogen sulphide
A factor a student chooses to change in an experiment is:
An independent variable.
What piece of apparatus is used to measure small volumes of liquid?
A pipette.
What does adding impurities to water do to its boiling point?
It will raise the boiling point.
What happens to the rise of most objects when the temperature rises?
The size will increase.
A substanc
