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120 Cards in this Set
- Front
- Back
Atom
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Smallest part of an element
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Element
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A substance which consists of only one type of atom
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Compound
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A substance consisting of two or more different elements that are chemically combined
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Mixture
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Two or more different elements which are not chemically combined
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Metal ions
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Lose electrons to form positive ions
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Non-metal ions
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Gain electrons to form negative ions
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Ionic bond
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Metal atom and a non-metal atom bonding by transferring electrons
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The number of outer electrons equals..
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Its group number
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Ionic compounds-melting/boiling point?
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They have high melting and boiling points because they have strong electrostatic bonds in all directions which all need to be broken in order to be boiled or melted
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Covalent bond
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Two non-metal atoms bond by sharing electrons
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Molecule
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Two or more atoms join together chemically
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Simple molecules-melting/boiling point?
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They have low melting and boiling points because they have weak intermolecular forces
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Ionic compounds - conduct electricity?
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Even though they are made up of ions they have no overall charge. However, when melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and carry the current.
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Simple molecules - conduct electricity?
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Simple molecules do not have an overall electrical charge and so they do not conduct electricity
Also, they are insoluble in water |
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Macromolecule-melting/boiling point?
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They have high melting points because the structures are held together by strong covalent bonds
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Giant covalent structure-conduct electricity?
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They do not contain ions so they do not conduct electricity
Also, they are insoluble in water |
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Elements in Group 1 form ionic compounds with what charge?
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Single positive charge
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Elements in Group 7 form ionic compounds with what charge?
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Single negative charge
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Electrostatic charge
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The force of attraction between oppositely charged ions acting in all directions
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Metal structure
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Giant regular pattern
Electrons in outer shell are delocalised and so can move through the structure. This causes electrostatic attractions between the metal ions and the free electrons |
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Macromolecule
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Giant covalent structure
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What forces are overcome when a substance melts or boils?
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Covalent bonds
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What substances consist of simple molecules?
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Gases, liquids or solids which have relatively low melting or boiling points
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Ionic compound
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A giant ionic lattice
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Examples of macromolecules (3)
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Diamond
Silica (silicon dioxide) Graphite |
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Structure of diamond
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A macromelucule where each carbon atom is covalently bonded to four other carbon atoms
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Structure of graphite
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A macromolecule where each carbon atom covalently bonds to three other carbon atom - leaving one delocalised
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Graphite properties -why?
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Soft and slippery because there are weak intermolecular forces between the layers so they can easily slide over each other
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Graphite's delocalised electrons is similar to...
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Metals
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Fullerene
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Formed with different numbers of carbons
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Structure of fullerene
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Based on hexagonal rings of carbon atoms
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Uses of fullerene
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Drug delivery into the body
Lubricants Catalysts Nanotubes e.g. tennis rackets |
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Metal - conduct electricity?
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Yes because of their delocalised electrons
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Metal properties- why?
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Can be bent or shaped because the layers are able to slide over each other
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Conduction depends on...
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The ability of electrons to move throughout the metal
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Alloy
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Two or more different metals
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Alloy characteristics - why?
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The different metals used each have a different atom size - distorting the structure, making it more difficult for the layers to slide over each other, thus making alloys harder than pure metals
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Shape memory alloy - property and example
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Can return to original shape after being deformed
E.g. dental braces - nitinol |
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What do the properties of polymers depend on? (2)
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What they are made from
The conditions under which they were made |
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Thermosoftening polymer structure
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Individual tangled chains with with weak intermolecular intermolecular forces (no cross links)
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Thermosetting polymer structure and property
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Chains with cross links between them
They do not melt when heated |
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Low density and high density poly(ethene) is produced by (2)
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Using different catalysts and reaction times
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Nanoscience
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Structures which are 1-100nm in size
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Nanoparticle properties (2)
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Different to the same materials in bulk
High surface to volume ratio |
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Uses of nanoparticles (7)
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Computers
Catalysts Coatings Sensors Stronger and lighter construction materials Sun cream Deodorants |
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Relative mass of a proton
Relative mass of a neutron Relative mass of an electron |
1
1 Negligible |
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Mass number
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Total number of protons and neutrons in an atom
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Isotope
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Same element with different mass numbers - some may have more neutrons than another
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Relative atomic mass
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Mass number number compares every element to the carbon 12 isotope
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Relative formula mass
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The sum of the relative atomic mass in a compound
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Mole
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The relative formula mass of a substance in grams
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Advantages of a mass spectrometer (3)
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Accurate
Rapid Sensitive - only needs a small sample |
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Chemical analysis
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Identifies additives in foods
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Paper chromatography
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Detects artificial colours
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Gas chromatography
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The compounds needed to be identified are vaporised and then carried by a gas which is filled with a solid material. The compounds move at different speeds causing them to seperate.
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Retention time
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The time taken for a substance to travel through the column in a gas spectrometer
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Mass spectrometer
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Can be linked to a gas spectrometer; it finds out the relative atomic mass of each substance passing through and thus can help identify the substance
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The number of peaks on a gas chromatograph shows
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The number of compounds present
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The position of the peak on a gas chromatograph shows
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The retention time
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Calculating percentage mass of an element in a compound
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(Relative mass of element in compound ÷ relative formula mass of compound) × 100
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Calculating the empirical formula
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Divide the mass of each element by their atomic mass
Divide each of these answers by the smallest to get the ratio |
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Moles equals
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Mass ÷ Mr
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Ar
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Atomic mass
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Mr
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Relative formula mass
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Why do we not get the maximum theoretical yield? (3)
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The reaction may not go to completion if it's reversible
Some of the product may be lost Some of the reactants may react in ways different from what is expected |
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Yield
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Amount of product obtained
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Rate of reaction
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Amount of reactant/amount of product produced ÷ time
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Activation energy
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The minimum amount of energy particles must have in order to react
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Ways of increasing the rate of reaction (5)
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Increase temperature
Increase pressure Increase concentration Increase surface area Using a catalyst |
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Why asre catalysts used in industrial processes?
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Reduces costs
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Exothermic reaction
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Transfers energy to surroundings
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Examples of exothermic reaction
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Combustion
Oxidation Neutralisation Hand warmers |
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Endothermic reaction
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Takes in energy from the surroundings
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Examples of endothermic reactions
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Thermal decomposition
Injury packs |
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Metal + acid makes
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Salt + hydrogen
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Problem with making a soluble salt from a metal
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Some are too reactive and some are not reactive enough
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Acid + base makes
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Salt + water
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Base
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Insoluble alkaline
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Acid + alkali makes
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Salt + water
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Describe the process of making a salt from an insoluble base
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The base is added to the acid until no more will react
The excess solid is then filtered off |
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How can we tell when an acid and alkali have completely reacted?
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By using an indicator because it should be neutral
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Precipitate
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Insoluble salt
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Uses of a precipitate
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Removing unwanted ions
Treating water |
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Examples of bases
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Metal oxides and hydroxides
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Alkali
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Soluble hydroxide
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Hydrochloric acid makes
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Chlorides
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Nitric acid makes
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Nitrates
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Sulfuric acid makes
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Sulfates
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Ammonia dissolves in water to make
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Alkaline solution
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What is the alkaline solution made from ammonia used for?
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Ammonium salts which are used as a fertiliser
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Hydrogen ions make solutions
H+(aq) |
Acidic
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Hydroxide ions make solutions
OH-(aq) |
Alkaline
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pH scale 1
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Very acidic
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Acid + alkaline hydroxide solution makes
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Neutral salt solution + water
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pH scale 7
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Neutral
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All group 1 metal compounds are
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Soluble
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All nitrates are
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Soluble
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All chlorides are
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Soluble except silver and lead
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All chlorides are
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Soluble except silver and lead
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All sulfates are
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Soluble except for calcium, lead and barium
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All chlorides are
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Soluble except for group 1 metal carbonates
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Describe the method of making a soluble salt from a metal and acid
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Place both reactants in a flask, the hydrogen produced will simply bubble away leaving you with the salt which can form crystals
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Describe the method of making a soluble salt from a metal oxide (insoluble base) and acid
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Place both reactants in a beaker until no more will react and then filter it to remove any excess.
In order to get rid of the oxygen produced you must boil the solution which will leave you with the salt. Leave this salt near a window and it will form crystals |
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Acid + carbonate makes
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Salt + water + carbon dioxide
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Describe the method of making a soluble salt from an acid and an alkali (soluble base)
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Add indicator to the alkali and then add drops of acid until it turns neutral. Leave this solution in an evaporation disk to get rid of the water produced to let it form crystals
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Describe the method of making a soluble salt from an acid and carbonate
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Place both in a flask, carbon dioxide will bubble away. Leave the solution to evaporate and then this will form crystals
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Describe the method of making an insoluble salt from two soluble solutions
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Pour one into the other and then filter it
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Electrolysis
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Passing an electric current through an ionic substance causing it to break down into its elements
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Electrolyte
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Substance broken down during electrolysis
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At the negative electrode
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The positive ions are attracted; they gain electrons to become neutral
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Reduction
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Gaining electrons
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At the positive electrode
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Negative ions are attracted; they lose electrons to become neutral
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Oxidation
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Losing electrons
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Half equation of Cl at the positive electrode
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2Cl-~>Cl2+2e-
2C-2e-~>Cl2 |
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Why is cryolite used during the electrolysis of aluminium?
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It lowers the melting point of aluminium oxide from 2000 go 900 degrees centigrade
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What forms at the negative electrode in aluminium oxide electrolysis?
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Aluminium
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What forms at the positive electrode in aluminium oxide electrolysis?
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Oxygen ~> Carbon dioxide
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The electrolysis of sodium chloride solution produces
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Hydrogen from the sea water at the negative electrode and chlorine from the sodium chloride at the positive electrode.
Sodium hydroxide is also produced |
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Use of sodium hydroxide
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Soap
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Uses of chlorine
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Bleach
Plastics |