Chemistry Unit 5

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Why is white phosphorus stored under water?
because it simultaneously ignites in air
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Why is P4O10 the common representation not P2O5?
this is how it exists more commonly
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Why does P4O10 have a higher melting point than sulphur(4) oxide?
because it is bigger and therefore the vdi forces are stronger and require more energy to break
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Why is the hydration enthalpy of fluoride ion are negative than that of a chloride ion?
fluoride ion is smaller and therefore has a larger charge density and is able to attract the partially positive H atom more strongly
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Why is a reaction with a positive entropy change always feasible?
because deltaG will always be negative
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Why are metal complexes different colours?
depends on the oxidation state of the ligand, due to different electron energy levels the wavelength of light being absorbed differs
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Write equation and describe observations of reaction of sodium with water?
vigorous, fizzes rapidly due to heat released - 2Na+2H2O--> 2NaOH(aq) + H2
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Write equation and describe observations of reaction of magnesium with water?
1. In room temp: Mg+2H2O--> Mg(OH)2 + H2 2. If Magnesium is heated : 2Mg + 2H2O--> 2MgO(s) + H2
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Write equation and describe observations of reaction of sodium with oxygen?
Burns brightly- yellow flame 2Na + 1/2O2 ---> Na2O (s)
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Write equation and describe observations of reaction of magnesium with oxygen?
Burns brightly - white flame 2Mg + O2 ---> MgO9(s)
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Write equation and describe observations of reaction of aluminium with oxygen?
if powdered and lowered into O2 gas chamber - 4Al + 3O2--> 2Al2O3
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Write equation and describe observations of reaction of silicon with oxygen?
must be heated strongly Si (s) + O2(g) --> SiO2 (s)
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Write equation and describe observations of reaction of phosphorus with oxygen?
White P simultaneously ignites in air, Red must be heated -4P+5O2--> P4O10
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Describe the structure of Sodium oxide
Na2O --> giant ionic bonding
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Describe the structure of Magnesium oxide
MgO--> giant ionic bonding
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Describe the structure of Aluminium oxide
Al2O3-->Giant ionic bonding
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Describe the structure of Silicon dioxide
SiO2--> macromolecular
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Describe the structure of Phosphorus oxide
P4O10 --> covalent molecule
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Describe the structures of sulfur trioxide and dioxide
SO3--> molecular
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What are the acidic period 3 oxides and how do they react with water?
P4O10: P4O10+H20--> 4H3PO4 , SO2+H2O--> H2SO3 (H+ + HSO3-) (only partially dissociates), SO3+H2O--> H2SO4 (H+ + H2SO4-)
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What are the basic period 3 oxides and how do they react with water?
1. Na2O + H2O --> 2NaOH(--> 2Na+ + 2OH-) 2. MgO + H2O--> Mg(OH)2 which partially dissociates to ---> Mg2+ + 2OH-
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What oxides are not soluble in water and why?
Al2O3 - ionic bonding is too strong as it has covalent character 2. SiO2- due macromolecular structure (can't be affected by water)
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What is the reaction of Na2O with an acid?
Na2O + H2SO4 --> NaSO4 + H2O
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What is the reaction of MgO with an acid?
MgO + 2HCL --> MgCl2 (aq) + H2O
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What is the reaction of Al2O3 with an acid and an alkali?
1. Al2O3 + 6HCL--> 2AlCl3 + 3H2O 2. Al2O3 + 2NaOH-->2NaAl(OH)
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What is the reaction of P4O10 with an alkali?
P4O10 + NaOH --> NaH2PO4 + H2O .x3... P4O10+3NaOH--> Na2PO4 + 3H2O
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What is the reaction of So2 with an alkali?
1. SO2 + NaOH --> NaHSO4 2. NaHSO4 + NaOH --> Na2SO3 +H2O
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What is an example of an autocatalysis reaction?
2MnO42- + C2O42- + 16 H+ --> 2Mn2+ + 10CO2 + 8H2O
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Which metal donated electrons in an ECC?
The more negative (more reactive)
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What are the conditions for calculating emf?
Standard conditions - 298 k , 100kpa and 1moldm-3 conc of each solution
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How to calculate emf?
write the cell rep, right - left
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What are some pros of fuel cells?
do not need electrical recharging just hydrogen and oxygen supply , water waste product - no toxic chemicals
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Why is sodium more reactive than magnesium?
Takes less energy for sodium to lose and e- than for Magnesium to lose 2
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Why is SiO2 considered an acid if it does not dissolve in water?
It reacts with acids
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Other cards in this set

Card 2

Front

Why is P4O10 the common representation not P2O5?

Back

this is how it exists more commonly

Card 3

Front

Why does P4O10 have a higher melting point than sulphur(4) oxide?

Back

Preview of the front of card 3

Card 4

Front

Why is the hydration enthalpy of fluoride ion are negative than that of a chloride ion?

Back

Preview of the front of card 4

Card 5

Front

Why is a reaction with a positive entropy change always feasible?

Back

Preview of the front of card 5
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