Ammonia Chemical Bonding Worksheet Page 23
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28(ii)
low pressure
or up to and including 10 atmospheres
1
(low pressure) favours a reaction in which
more molecules are formed
2 moles → 4 moles
(2 molecules → 4 molecules)
independent marks
1
(iii)
nickel and it is a transition / transitional
element / metal (owtte) or nickel and
variable oxidation state / number or it is
similar to other named transition elements
e.g. iron
1
(b)
(i)
(bonds broken =) 2005 (kJ)
1
(bonds formed =) 2046 (kJ)
1
energy change = 2005 – 2046 = (–)41
for correct subtraction ignore sign
1
(ii)
(exothermic)
if in part (b)(i) answer is not 41
answer is consequential on endothermic or exothermic shown
accept correct reasoning for incorrect answer from (b)(i)
energy given out forming new bonds
do not accept energy needed to form new bonds
1
greater than energy put in to break old bonds
accept exothermic and more energy given out than taken in for 1
mark
accept negative value for energy change or energy in products
less than energy in reactants for 1 mark
1
[10]
M6.
(a)
(i)
78-80%
1
(ii)
proteins
accept amino acids
1
Page 23 of 28
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