Unit 5 Chemistry

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  • Created by: Sopha8
  • Created on: 02-03-15 16:10
Explain exothermic and endothermic
exo: Releases heat, negative value, making bonds. Endo: Absorbs heat so positive value, breaking bonds
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How do you calculate enthalpy change?
enthalpy change= energy absorbed to break bonds-energy released when making
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What is entropy affected by?
1) physical state-increasing as you go to gas 2) dissolving increases entropy 3) more particles=more entropy 4) spontaneous endothermic reactions
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Whats the equation for entropy change? when is a reaction feasible?
total entropy change= entropy change of system + entropy change of surrondings. must be positive
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Explain free-energy change
0 or less for reaction to be feasible, ..G= ..H-T..S system
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Is Mg or Na more reactive and why? Reactions with water?
Na becuase it loses 1 electron whereas Mg loses 2. Na reacts vigorously produce strong alkalie, Mg slowly and produces weak alkali reacts faster with steam
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What are the period 3 oxides?
Na..O, MgO, Al..O.., SiO.., P..O.., SO..
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Explain the trend in melting points of period 3 oxides
Na..O, MgO and Al..O.. are high as strong forces of attraction between ions, MgO highests as 2+ions Al..O.. lowest as partially covalent, SiO.. high as giant macromolecular, P..O.. and SO.. low as simple covalent, weak van der waals
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What is a redox reaction?
Oxidation is loss of elecrons so gain oxidation no. reduction is gain of electrons so decrease in oxidation no.
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Whats the diagram for a electrochemical cell?
..
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How do you calculate cell potential (e.m.f)?
E cell = E reduced (right on cell diagram)- E oxisided (left)
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What are the conditions for the standard hydrogen electrode?
1. 1.00 moldm-3 ion solution 2. 298K 3. 100kPa
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Card 2

Front

How do you calculate enthalpy change?

Back

enthalpy change= energy absorbed to break bonds-energy released when making

Card 3

Front

What is entropy affected by?

Back

Preview of the front of card 3

Card 4

Front

Whats the equation for entropy change? when is a reaction feasible?

Back

Preview of the front of card 4

Card 5

Front

Explain free-energy change

Back

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