Chemistry paper 1

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What does the particle theory model?
Models the states of matter, with particles described as hard spheres.
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If the state of matter is solid what is the: arrangement of particles, movement of particles and the relative energy of particles?
Close together (regular pattern), vibrate about fixed positions,least stored energy.
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If the state of matter is liquid what is the: arrangement of particles, movement of particles and the relative energy of particles?
Close together at random, move around each other, → (long arrow).
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If the state of matter is gas what is the: arrangement of particles, movement of particles and the relative energy of particles?
Far apart at random, fast in all directions, has the most stored energy.
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What happens during a state change?
Energy is transferred to or from the particles, the arrangement of particles changes, the movement of particles changes.
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What begins to happens to a substance at its melting point?
It: melts if energy is transferred to the particles, freeze if energy is transferred to the surroundings.
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What begins to happen to a substance at its boiling point?
A substance begins to: boil if energy is transferred to the particles, condense if energy is transferred to the surroundings.
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What happens when a substance evaporates if it changes from a liquid to a gas below its boiling point?
A substance evaporates if it changes from a liquid to a gas below its boiling point: particles with high enough energy leave the surface of the liquid, the remaining particles have less energy, the liquid cools down unless heated
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What is an element?
A substance that consists only of atoms with the same atomic number.
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What is a compound?
A substance that consists of atoms of two or more different elements ,chemically joined together.
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Why are most substances mixtures?
because they contain different elements and/or compounds. Mixtures or impure substances .The parts of a mixture are not chemically joined together.
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What is distillation?
When you can separate 2 liquids from mixtures using distillation.
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What type of distillation is used to separate a solvent from a solution?
Simple distillation.
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What type of distillation is used to separate a liquid from a mixture of miscible liquids ?
Fractional distillation.
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How does simple distillation work?
Works because the solute in the solution has a much higher boiling point than the solvent.
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How does fractional distillation work?
Works because the liquids in the mixture have different boiling points.
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How does filtration work?
because the filter paper has tiny holes called pores which are large enough to let water molecules and dissolved substances through, small enough to stop insoluble solid particles going through.
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How does crystallisation work?
works because: the solubility of the solute goes down as the saturated solution cools, crystals form from the excess solute.
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What must potable drinking water have?
potable drinking water must have: low levels of contaminating substances, low levels of microbes.
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What are the 3 main stages that happen in water treatment?
Sedimentation,filtration,chlorination.
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What happens during sedimentation?
large insoluble particles sink to the bottom of the tank.
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What happens during filtration?
small insoluble particles are removed by filtering through beds of sand.
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What happens during chlorination?
chlorine gas is bubbled through the water to kill microbes.
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What does tap water contain?
dissolved salts, dissolved chlorine.
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Why is sea water unsafe to drink?
The sea waters concentration is too high.
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What are the properties of acids?
The pH of their aqueous solution is less than 7. They are a source of hydrogen ions H+ in solution.
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What are the properties of alkalis?
The pH of their aqueous solution is more than 7. They are a source of hydroxide ions, OH in solution.
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What are indicators?
Indicators are substances that have different colours, depending on their pH.
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How does a salt form?
A salt forms when hydrogen ions in an acid are replaced by metal ions or ammonium ions.
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How many parts of a salt consist of?
2 parts. First part=the metal in the base, Second part=from the acid used.
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Reactive metals react with acids to produce a salt and hydrogen only, What is the formula?
metal+acid→salt+hydrogen
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Metal carbonates react with acids to produce a salt, water and carbon dioxide, What is the formula?
metal carbonates+acid→salt+water+carbon dioxide.
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What is a neutralisation reaction?
A neutralisation reaction is a reaction between an acid and a base.
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What is a titre?
The titre is the volume of acid added to exactly neutralise the alkali.
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How do you normally calculate the mean titre using your concordant results only?
mean titre=sum of concordant titres/number of concordant titres.
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What is concordant titres?
Concordant titres are identical to each other, or very close together.
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What is electrolysis used for?
Electrolysis is used to decompose ionic compounds in the molten state or dissolved in water.
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What is an electrolyte?
An electrolyte is an ionic compound in the molten state (liquid) or dissolved water.
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What is electrolysis?
a process in which electrical energy, from a direct current supply, decomposes an electrolyte.
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What are anions?
negatively charged ions that move to the positive electrode.
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What are captions?
positively charged ions that move to the negative electrode?
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Where can ions move and not move?
ions can move about in liquids and in solutions, cannot move about in solids.
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What is the formula when hydrogen is produced if a metal reacts with water?
metal+water→metal hydroxide+hydrogen.
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What is the formula when hydrogen is produced if a metal reacts with a dilute acid?
metal+acid→salt+hydrogen.
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How can you work out the relative reactivity of metals?
Using displacement reactions.
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What will a more reactive metal do during displacement?
It will displace a less reactive metal from its salts in solution.
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How are cations formed?
when metal atoms lose electrons this is when cations form. A full outer shell is obtained when a metal atom loses electrons.
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What do displacement reactions involve?
Oxidation and reduction.
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What is an ore?
An ore is a rock that contains enough of a metal to make its extraction econominal.
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Where are unreactive metals placed such as gold on the reactivity series?
At the bottom.
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Where are unreactive metals found?
They are found in the earths crust.
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What is oxidation?
Oxidation is the gain of oxygen by a substance.For example, magnesium is oxidised to a magnesium oxide in the air: 2MG+O2→2MgO
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What is reduction?
Reduction is the loss of oxygen by a substance.For example, zinc oxide is reduced to a zinc when its heated with carbon:ZnO+ C→CO
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When do metals corrode?
Metals corrode when they react with substances around them, such as air and water.
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How are most metals extracted?
most metals are extracted by the reduction of ores found in the earths crust.
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What are the 3 types of extraction?
Metal extraction, iron extraction, aluminium extraction.
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What do extracting metals from their ores do?
Uses up limited resources, uses a lot of energy and damages the environment
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What does recycling metals mean?
metal ores will last longer, less energy is needed, fewer quarries and mines are needed, less noise and dust are produced and less land is needed.
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What are the drawbacks of recycling?
Used metal items must be collected and transported to the recycling centre, different metals must be removed from used items and sorted, recycling saves different amounts of energy, depending on the metal involved.
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What does an LCA likely need data at most stages?
the use of energy, the release of waste materials, transport and storage.
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Are chemical reactions reversible?
Yes.
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What is the haber process?
The haber process is a reversible reaction between nitrogen and hydrogen to from ammonia.
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If the state of matter is solid what is the: arrangement of particles, movement of particles and the relative energy of particles?

Back

Close together (regular pattern), vibrate about fixed positions,least stored energy.

Card 3

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If the state of matter is liquid what is the: arrangement of particles, movement of particles and the relative energy of particles?

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Preview of the front of card 3

Card 4

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If the state of matter is gas what is the: arrangement of particles, movement of particles and the relative energy of particles?

Back

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Card 5

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What happens during a state change?

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