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36 Cards in this Set
- Front
- Back
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What sign is delta H for different kinds of reactions? |
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What 3 things are required in a thermochemical equation? |
1) The mole ratio 2) The states of matter (g) (l) (s) (aq) 3) The heat energy (in KJ/mol) |
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What is the molar enthalpy of combustion? |
Is the quantity of heat energy released when 1 mol of pure element is burnt completely in oxygen under constant pressure, creating the given reaction: C5H11OH + 7.5O2 -> 5CO2 + 6H20 |
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What is the molar enthalpy of a solution? |
Is the quantity of heat energy released or absorbed when 1 mol of substance dissolves in sufficient water so no further dilution causes heat energy changes. |
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What is the molar enthalpy of neutralisation? |
Is the quantity of heat energy released when 1 mol of hydrogen ions is transferred from an acid to base in aqeuous solution. |
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Calculate heat energy and molar enthalpy change. |
(where q = heat energy) |
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What is the equation for the fermentation of glucose and what conditions are required for it to occur? |
C6H12O6 -> 2C2H5OH + 2CO2 - Optimum temperature between 20 and 30 degrees. Otherwise, enzymes become ineffective. - Moderately acidic conditions required. - Oxygen must be entirely excluded. - Nutrients required for yeast growth. |
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Using a spirit burner, what errors are present? |
Systematic: (Cannot be reduced by repeating) 1) Combustion occurs in air, not complete combustion. 2) Not all heat energy absorbed by the water. Random: (Can be reduced by more testing) 1) Not high resolution on measuring devices 2) Stirring of water was not constant and therefore not constantly heated. |
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What is the difference between galvanic and electrolytic cells? |
Galvanic cells produce electricity while electrolytic cells use electricity to cause electrolysis. |
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What are the signs of the electrodes in galvanic and electrolytic cells? |
Vans run over cats and that's positive (Galvanic, cathode is positive, anode negative). (Electrolytic, anode is positive, cathode negative). |
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In what direction do electrons flow? |
From the anode to the cathode. |
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What is a property of oxidation? |
Oxidation is the increase in oxidation number but the decrease in electrons. |
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What is the general rule to do with equations of electrochemistry? (Electrode equations) |
Anode: X -> X+ + e-
Cathode: X+ + e- ->X (Electrons on left? No? Oxidation.) |
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What are the oxidiser and reducer pairs? |
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Explain the processes of a fuel cell |
- Porous electrodes, such as carbon, have catalysts placed within them. This allows for greater surface area of contact. - Fuel (hydrogen) is added as the anode and undergoes oxidation. - Oxidant (oxygen) is supplied to the cathode and undergoes reduction. |
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What are the advantages and disadvantages of fuel cells? |
Advantages: - Will continuously produce electricity so long as fuel and oxidant is supplied. - Works at a high efficient (70-80%). - Better mass to power output ratio. - Electrodes and electrolyte are not used on process. - Silent operation, no maintenance or pollutant gases. Disadvantages: - High purity fuel is costly - Impurities such as KOH can poison the electrodes, forming potassium carbonate which will clog electrodes. - Medium to high temperatures needed. - Some electrolytes are extremely corrosive. |
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How do rechargeable galvanic cells work? |
(When reversed, the anode becomes the cathode and vice versa). |
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How are various rates of reactions found? |
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What is rate of reaction dependent upon? |
OF-ME Depends on: 1) Orientation of particles. 2) Frequency of collisions. 3) Magnitude of activation energy. 4) Energy of collisions |
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What do the energy profile diagrams look like? |
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What must reactants have in order to have collisions being productive? |
- Have a high enough activation energy to break bonds. - Have orientation towards each other. |
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What factors affect the reaction rate? |
- Increasing the concentration of a solution increases the number of reactants in a unit volume. This increases the collisions per unit time, ergo increasing probability of productive collisions. (Pressure for gases also). - Increasing temperature of a solution increases the kinetic energy of reactants as they are more energetic. Hence, number of productive collisions with enough energy to break existing bonds increases. - Increasing surface area allows for more productive collisions, increasing the rate of reaction. |
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How do catalysts change reaction rate? |
Catalysts provide reactants with an alternate pathway which has a lower activation energy. |
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What do the graphs of chemical equilibrium look like? |
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What are the properties of the Kc value? |
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What are the properties of La Châtelier's principle? |
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Explain the Haber process and its use. |
The Haber process is used to create ammonia. While the temperature used is high, it is the sweet spot between fast production and mass production. |
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How is sulfuric acid produced? |
Through the contact process. |
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What are the various definitions used in metal production? (e.g. raw materials etc). |
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In the industrial process, how is the cost of energy minimised? |
- Running the process constantly makes the process more efficient, using less energy to start over. - Lower temperatures used and more catalyst as to not reduce yield. - Using the heat produced (exothermic reaction) in creating other forms of energy. (Like fuels). |
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How are metals produced from ores? |
Uses acronym CCRR which stands for: Concentration of mineral: This is done by removing gangue. Not needed if gangue is low. Conversion of mineral in concentrate to substance for reduction: This is often done by roasting which makes a metal oxide (basic oxide). Reduction of metal compounds to the actual metal: Reducing agents or electrolysis. Refining: This involves removing impurities formed from reduction. |
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Using the knowledge of how metals are produced from ores, how is zinc produced? |
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How is aluminium produced?
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When the pressure of a system changes, what happens? |
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If temperature is changed, what does the equilibrium look like? |
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Using knowledge of Kc values, determine if a reaction is complete or incomplete. |
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