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36 Cards in this Set
- Front
- Back
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What is a mole? |
The precise number of atoms of any substance that will equal the relative atomic mass of that substance. One mole of carbon will be 12 grams as the Atomic Mass of carbon is 12. |
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What is the equation for number of moles? |
Number of moles = Mass in grams / Relative Formula Mass |
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What is Relative Atomic Mass? |
The mass of an atom of the element compare to one twelfth of the mass of an atom of carbon-12. |
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What is the equation for finding the percentage composition by mass of a substance? |
Percentage composition by mass = Atomic Mass of substance x number of atoms / Atomic Mass of whole compound |
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What is the formula for Concentration? |
Concentration = Number of Moles / Volume |
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What is a dm^3 equivalent to? |
One litre. |
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What does GDA stand for? |
Guideline Daily Amount. |
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What is the method for carrying out a titration? (4) |
Fill a beaker with a set amount of alkali. Fill a burette with acid. Whilst stirring, drip the acid into the alkali until the indicator changes colour. Record the amount of acid needed to neutralise the alkali. |
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What indicator can be used? |
Methyl Orange. Goes from red to yellow. |
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Why can't universal indicator be used for titrations? |
It has a gradual colour change, and a sudden colour change is needed. |
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What does the almost vertical line on a titration graph show? |
The endpoint. |
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How do you calculate the concentration of the acid in a titration? (4) |
Work out how many moles of the known substance you have. Work out the ratio of the acid to alkali by looking at the balanced equation. Determine the amount of acid needed to neutralise the alkali based on the ratio. Determine the concentration using the equation. |
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What can you use to measure gases produced by a reaction? |
Gas syringe: Plunger may be blown out in vigorous reactions. Upturned measuring cylinder: Doesn't work with games that dissolve in water. |
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What is the volume of a mole of any gas? |
24 litres at room temperature and pressure. |
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What is the reactant that limits the reaction? |
Limiting reactant. |
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What is the equilibrium? |
When the forwards reaction is equal to the backwards reaction. |
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What is a reversible reaction? |
A reaction when the products of the reaction can react to produce the original reactants. |
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What is required for an equilibrium to be reached? |
A closed system, meaning no chemicals can escape. |
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What can affect the position of the equilibrium? (3) |
Temperature. Pressure. Concentration. |
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How does temperature change the equilibrium? |
If decreased it moves to the exothermic direction to produce more heat. |
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How does pressure change the equilibrium? |
If increased it will move in the direction of fewer moles of gas to decrease pressure. |
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How does concentration change the point of equilibrium? |
If increased amount of reactants on one side it will shift to the other side to balance it out. |
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How does the contact process make sulfuric acid? (3) |
Sulfur + Oxygen - - > Sulfur Dioxide Sulfur Dioxide + Oxygen <--> Sulfur Trioxide Sulfur Trioxide + Water - - > Sulfuric Acid |
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What is the equation for the first step of the contact process? |
S + O2 - - > SO2 |
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What is the equation for the second step of the contact process? |
2SO2 + O2 <--> 2SO3 |
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What is the equation for the third step of the contact process? |
SO3 + H2O - - > H2SO4 |
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How can the reaction to make Sulfur Trioxide be optimised? |
Temperature: It is an exothermic reaction so it should be low, but that decreases speed so 450'C is optimum. Pressure: Should be high but that is expensive so normal atmospheric pressure is used. Catalyst: Vanadium Pentoxide is used. |
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Why are acids acidic? |
Because they ionise to produce H+ ions. |
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Why are strong acids better electrical conductors? |
They have more charged particles to carry the electrical charge. |
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Why do weak acids react slower than strong acids? |
They have a reversible reaction so "drip feed" the H+ ions as it needs time for the equilibrium to adjust. |
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What do Ionic equations show? |
Only the ions that react, not the spectator ions. |
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How do you test for Sulfate ions? |
Add diluted hydrochloric acid and barium chloride to the solution. If a white precipitate forms the original compound was a sulfate. |
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What are the colours of the precipitates of three main ions? |
Chloride ions = White lead chloride Bromide ions = Cream lead bromide Iodide ions = Yellow lead iodide |
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How do you test for chloride, bromide or iodide ions? |
Add dilute nitric acid and lead nitrate to the solution. |
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How do you create an insoluble salt? |
Mix two soluble substances, such as a nitrate as nitrates are soluble. |
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How do you extract the salt? (3) |
Mix the two reactants together in distilled water to create a precipitate. Filter the contents of the reaction by pouring it through filter paper. Rinse the contents of the filter paper using distilled water to get rid of all the soluble salts and leave it to dry. |
