Chemistry Flashcards

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  • Created by: AKR28
  • Created on: 21-12-13 17:36
How is the speed of diffusion and the molecular mass of the substance related?
The rate of diffusion depends on the relative molecular mass. Substances with a high relative molecular mass diffuse more slowly than those with a low relative molecular mass.
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What is chromatography?
Chromatography is a method for separating and purifying coloured compounds using filter paper and a solvent.
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What is purity in Chemistry?
When chemists talk about purity they mean that there is only one substance present.
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What is decanting?
Decanting is simply pouring off the solution.
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What is centrifugation?
A centrifuge is a machine which spins test tubes round and round at very high speeds. The spinning pulls the solid to the bottom of the tube. You can then decant the liquid from the solid.
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When is solvent extraction used?
Solvent extraction can be used to separate two solids dissolved in a liquid. This is especially useful if one of the solutes is volatile - evaporates easily.
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What is simple distillation?
Simple distillation is used to separate water from a dissolved salt.
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What is fractional distillation?
Fractional distillation is used to separate a mixture of liquids with different boiling points.
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What are the uses of radioisotopes?
One of the most important medical uses of radioisotopes is in cancer treatment. They can also be used to sterilise medical equipment. Industrially, radioisotopes can be used to check for leaks in oil and gas pipelines.
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What is the valency of an atom?
The valency of an atom can be defined as the number of electrons lost or gained to form a complete electron shell in a covalent or ionic compound.
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Describe the properties of ionic compounds.
Ionic compounds have high melting and boiling points. They are soluble in water. Thirdly, ionic compounds conduct electricity when molten or dissolved because the ions are free to move.
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What are allotropes?
Allotropes are different forms of the same element. For example diamond and graphite are allotropes of carbon.
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Describe the properties of diamonds.
Diamonds have high boiling and melting points due to the formation of a giant lattice. Diamond is also very hard but can still form colourless, glittering crystals.
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Describe the properties of graphite.
Graphite is a black shiny solid. The strong covalent bonding means that the melting and boiling points of graphite are very high. Graphite is slippery and can be easily scratched. The delocalised electrons mean that graphite conducts electricity.
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What is the formula of an ammonium ion?
NH4+ is the formula of an ammonium ion.
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What is the formula of a hydrogencarbonate ion?
HCO3- is the formula of a hydrogencarbonate ion.
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How do you calculate the number of moles of a substance?
Number of Moles = Mass of Substance taken (g) / Mass of one mole of the substance (g)
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What are limiting reactants?
A limiting reactant is the reactant that is not in excess.
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How do you calculate the concentration of a substance?
Concentration (mol/dm3) = Number of Moles / Volume (dm3)
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What are the products of the electrolysis of brine?
Chlorine gas, Hydrogen gas and Sodium Hydroxide are the products of the electrolysis of brine.
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Briefly describe the process of copper refining.
Anode: Impure Copper, Cathode: Pure Copper, Electrolyte: Copper Sulfate solution
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What are the uses of electroplating?
Protection of metals from corrosion. Improvement of appearance of the metals.
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Briefly describe the process of extracting aluminium.
Electrodes are Carbon/Graphite. Molten aluminium oxide is mixed with cryolite. Aluminium is formed at the cathode and Oxygen is formed at the anode.
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Describe an exothermic reaction.
In an exothermic reaction the energy taken in to break the bonds of the reactants is less than the energy released when new bonds are made. This means that heat is released to the surroundings and the enthalpy change is negative.
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Describe an endothermic reaction.
In an endothermic reaction the energy taken in to break the bonds of the reactants is more than the energy given out when new bonds are made. This means that heat is taken in and the enthalpy change is positive.
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Describe the basics of an electrolytic cell.
An electrolytic cell contains two electrodes of different reactivity dipping in an electrolyte. The electrode higher in the reactivity series is the negative pole of the cell. In an electrolytic cell the electrons move from the - pole to the + pole.
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What are the advantages of a hydrogen-oxygen fuel cell?
A hydrogen-oxygen fuel cell produces only water as a product. A hydrogen-oxygen fuel cell is efficient and non-polluting.
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How does the surface area affect the rate of reaction?
Increasing the surface area of a solid reactant increases the rate of reaction. This is because the chances of collisions between the atoms/molecules are increased.
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How does the concentration affect the rate of reaction?
Increasing the concentration of the reactants increases the rate of reaction as a more concentrated substance has more particles and therefore the chances of collisions have been increased.
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How does the temperature affect the rate of reaction?
The rate of reaction increases with an increase in temperature because particles have more energy so they move faster and collide more frequently. The collisions that take place are more energetic so are more likely to result in a reaction happening.
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Describe the photochemical reaction that takes place in Photography?
The surface of black and white photographic film contains tiny crystals of silver bromide mixed with gelatine. When light shines on the film the silver bromide is activated. Some of the silver bromide decomposes to form silver.
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What are the characteristics of a reaction taking place in dynamic equilibrium.
The products can react to form the original reactants again. An equilibrium can only take place in a closed system. At equilibrium, the rate of the forward reactions is the same as the rate of reverse reaction.
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What does increasing the concentration of a reactant in an equilibrium reaction do?
Increasing the concentration of a reactant moves the reaction in the direction of the products until the equilibrium balance is restored.
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What does increasing the pressure of a reactant in an equilibrium reaction do?
Increasing the pressure moves the reaction in the direction of the lower number of gas molecules.
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What effect does increasing the temperature have on an endothermic reaction?
For an endothermic reaction, increasing the temperature moves the reaction to the right in the direction of the products.
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What effect does increasing the temperature have on an exothermic reaction?
For an exothermic reaction, increasing the temperature moves the reaction to the left in the direction of the reactants.
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What is the difference between oxidation and reduction.
Oxidation is loss of electrons. Reduction is gain of electrons.
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What is formed when aqueous ammonia is reacted with an acid?
A ammonium salt is formed but no water is present.
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What is formed when an ammonium salt reacts with a base?
A salt, ammonia and water are formed.
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What are the differences between strong acids/bases and weak acids/bases?
Compared with weak acids/bases, strong acids/bases have a higher electrical conductivity, a lower/higher pH (lower for acids, higher for bases) and a faster rate of reaction.
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Are salts of Group I elements soluble or insoluble?
All salts of Group I elements are soluble.
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Are nitrates soluble or insoluble?
All nitrates are soluble.
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Are ammonium salts soluble or insoluble?
All ammonium salts are soluble.
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Which chlorides, bromides and iodides are insoluble?
Chlorides, bromides and iodides of silver and lead are insoluble compounds.
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Which sulfates are insoluble?
Sulfates of calcium, barium and lead are insoluble compounds.
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Which hydroxides and carbonates are soluble?
Group I hydroxides and carbonates are soluble (Calcium hydroxide is slightly soluble).
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Which oxides are soluble?
Group I and II oxides react with water.
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What is the test for an aluminium cation?
With aqueous sodium hydroxide a white precipitate which is soluble in excess is formed. With aqueous ammonia a white precipitate which is insoluble in excess is formed.
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What is the test for a calcium cation?
With aqueous sodium hydroxide a white precipitate which is insoluble in excess is formed. With aqueous ammonia no precipitate or very slight white precipitate is formed.
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What is the test for a copper (II) cation?
With aqueous sodium hydroxide a light-blue precipitate which is insoluble in excess is formed. With aqueous ammonia a light-blue precipitate which is soluble in excess is formed.
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What is the test for a iron (II) cation?
With aqueous sodium hydroxide a grey-green precipitate which is insoluble in excess is formed. With aqueous ammonia a grey-green precipitate is formed which is insoluble in excess is formed.
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What is the test for an iron (III) cation?
With aqueous sodium hydroxide a reddish-brown precipitate which is insoluble in excess is formed. With aqueous ammonia a reddish-brown precipitate which is insoluble in excess is formed.
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What is the test for a zinc cation?
With aqueous sodium hydroxide a white precipitate which is soluble in excess is formed. With aqueous ammonia a white precipitate which is soluble in excess is formed.
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What is the test for a chloride anion?
Add dilute nitric acid and aqueous silver nitrate. A white precipitate forms.
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What is the test for a bromide anion?
Add dilute nitric acid and aqueous silver nitrate. A cream precipitate forms.
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What is the test for an iodide anion?
Add dilute nitric acid and aqueous silver nitrate. A pale yellow precipitate forms.
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How do you identify carbonate ions?
Add dilute acid to the compound. If a carbonate is present you will see effervescence. Test to see if the gas given off is carbon dioxide using limewater.
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How do you identify nitrate ions?
Add aqueous sodium hydroxide, then aluminium foil and warm gently. Test the gas given off with a piece of damp red litmus paper placed at the mouth of the test tube. If ammonia is given off, the litmus paper will turn blue. Nitrate ions are present.
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How do you identify sulfate ions?
Add dilute hydrochloric acid. Add an aqueous solution of a soluble barium salt such as barium chloride or barium nitrate. If a white precipitate is formed the compound is a sulfate.
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What is brass, its properties and uses?
Brass is an alloy of copper and zinc. It is stronger than copper but still malleable. It is used for musical instruments and ornaments.
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What is bronze, its properties and uses?
Bronze is an alloy of copper and tin. It is very hard. It is used for some moving parts of machines, statues and bells.
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What is stainless steel, its properties and its uses?
Stainless steel is an alloy of iron, chromium and nickel. It does not rust like iron. It is used for car parts, cutlery, parts of chemical factories and surgical instruments.
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What is the ore of zinc blende?
The main ore of zinc is zinc blende which is zinc sulfide, ZnS.
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What is refinery gas?
Refinery gas has a boiling point of under 40 degrees Celsius. It is used for heating and cooling.
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What is gasoline?
Gasoline has a boiling point of between 40 and 100 degrees Celsius. It is used as a fuel for cars (petrol).
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What is naphtha?
Naphtha has a boiling point of between 80 and 180 degrees Celsius. It is used for making chemicals and especially plastics.
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What is kerosene?
Kerosene has a boiling point of between 160 and 250 degrees Celsius. It is used for jet aircraft and heating.
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What is diesel?
Diesel has a boiling point of between 250 and 300 degrees Celsius. It is used as a fuel for heavy vehicles such as lorries and tractors.
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What is the residue from the fractionating column used for?
Lubricating oil is used as lubricants, waxes and polishes. Bitumen is used for making road surfaces and sealing roofs.
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Other cards in this set

Card 2

Front

What is chromatography?

Back

Chromatography is a method for separating and purifying coloured compounds using filter paper and a solvent.

Card 3

Front

What is purity in Chemistry?

Back

Preview of the front of card 3

Card 4

Front

What is decanting?

Back

Preview of the front of card 4

Card 5

Front

What is centrifugation?

Back

Preview of the front of card 5
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Comments

dangosenpai

Awesome compilation of chem topics ! Thanx !

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