Chemistry OCR, C6

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What is the importance of chemical synthesis?
to provide, food additives, fertilisers, dyestuffs, paints and pigments
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What does the chemical industry make on a large scale?
bulk chemicals
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What does the chemical industry make on a smaller scale?
fine chemicals
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What are examples of acidic compounds?
solids: citric and tartaric acids, liquids: sulfuric, nitric and ethanoic acids, gases: hydrogen chloride
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What are examples of common alkalis?
hydroxides of sodium, potassium and calcium
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What is the pH scale?
measure of the acidity or alkalinity of an aqueous solution. Acids are substances that pH less than 7. Bases are the oxides and hydroxides of metals, soluble bases are called alkalis and have a pH greater than 7
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What can you use to detect acidity and alkalinity?
litmus paper, universal indicator and pH meters
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What can you use to measure pH?
use of universal indicator and pH meters
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What do acids react with to form a salt and water?
metal hydroxides, metal oxides and metal carbonates (when an acid reacts with a metal carbonate, it also produces carbon dioxide)
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What do acids react with to form a salt and hydrogen?
metals
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What acid produces chloride salts?
hydrochloric acid
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What acid produces sulfate salts?
sulfuric acid
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What acid produces nitrate salts?
nitric acid
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What is a neutralisation reaction?
the reaction of an acid with an alkali to form a salt
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What do acidic compounds produce when they dissolve in water?
aqueous hydrogen ions, H+ (aq)
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What do alkaline compounds produce when they dissolve in water?
aqueous hydroxide ions, OH- (aq)
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How is water made during a neutralisation reaction?
the hydrogen ions from the acid react with hydroxide ions from the alkali ions ( H+(aq) + OH- (aq) ==> H^2O (l) )
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What is an exothermic reaction?
release energy usually as heat because the products have less energy than the reactants did
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What is an endothermic reaction?
take in energy, so usually feel cold to the touch. This means the products have more energy than the reactants did
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What is a problem with endothermic reactions?
they can take a lot of energy to make them happen
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What is a problem with exothermic reactions?
they can reach very high temperatures if they aren't adequately controlled
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What are the stages in the chemical synthesis of an inorganic compound?
choose reactions to make required product, carry out a risk assessment, work out quantities of reactants to use, carry out reaction under suitable conditions, separate product from reaction mixture, purify product, measure yield and check purity
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What is the purpose of dissolving, crystallisation, filtration, evaporation, drying in an oven or desiccator?
to filter the product and check its purity
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Why is it important to purify the products?
the purity of the product is important as impurities can be dangerous
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What does a balanced equation for a chemical reaction show?
the relative number of atoms and molecules of reactants and products taking part in the reaction
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What does the atomic mass of an element show?
shows the mass of its atom, relative to the mass of other atoms
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How do you obtain the relative atomic masses of elements?
By looking at the periodic table and the bigger number on each element
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What do you need to know to calculate the relative formula mass of a compound?
the formula of the compound and the RAM of each of the atoms involved
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How do you find the mass of a product and reactants?
work out RFM of each substance, check the total mass of reactants equals the total mass of the products, find the ratio of mass of reactant to mass of product, use ratio to find how much of the product can be produced
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How can you calculate the percentage yield?
by comparing the actual yield and theoretical yield ( percentage yield = actual yield/ theoretical yield x100)
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How do you carry out a titration?
fill a burette with an alkali and take initial reading of the volume, use a pipette to measure aqueous acid into a conical flask, add drops of phenolphthalein to acid, drop by drop add in alkali from the burette, wait for solution to turn pink
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What is the formula to interpret titration results quantitatively?
percentage purity = actual mass of pure substance/ mass of impure substance x 100
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What are economic factors of carrying out chemical synthesis?
must produce a sufficient daily yield of product, optimum conditions should be used that give the lowest cost rather than the fastest reaction or highest percentage yield
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What are safety factors of chemical synthesis?
care must be taken when using chemicals that could harm the environment if there was a leak, must avoid putting harmful by-products into the environment, risk assessment must be carried out
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What is the rate of a chemical reaction?
the amount of products made in a given unit of time
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How can you find the rate of a chemical reaction?
weighing the mixture, measuring the volume of gas produced, observing the formation of a precipitate
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How do reaction rates vary with the size of solid particles?
large particles have a smaller surface area in relation to their volume, so fewer particles are exposed for collisions and collisions are less frequent.
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How do reaction rates vary with the concentration of solutions of chemicals?
in a low concentration there are fewer particles which are more spread out, this means particles will collide less frequently. In a high concentration the particles will collide more frequently
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How do reaction rates vary with the temperature of the reaction mixture?
an increase in temperature gives the reactant particles more energy to collide, so collide more frequently with more energy
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What does a catalyst do in a chemical reaction?
catalysts speed up chemical reactions while not being used up in the reaction
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How does a catalyst change the rate of chemical reactions?
lower the amount of energy needed for a successful collision, makes more of the collisions successful, speeds up the reaction
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What is the collision theory?
collision theory states that for two reactant particles to react they must collide. If reactant particles collide more frequently with more energy, they're more likely to have successful collisions, and the reaction will speed up
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What is activation energy?
when two reactant particles collide they need to have enough energy so that they don't bounce off each other
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Card 2

Front

What does the chemical industry make on a large scale?

Back

bulk chemicals

Card 3

Front

What does the chemical industry make on a smaller scale?

Back

Preview of the front of card 3

Card 4

Front

What are examples of acidic compounds?

Back

Preview of the front of card 4

Card 5

Front

What are examples of common alkalis?

Back

Preview of the front of card 5
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