TOPIC 5 TEST MS
1.   (a)    (i)      M1    The peak of the new curve is displaced to the right.
M2    All of the following are required
•        The new curve starts at the origin
•        The peak of the new curve is lower than the original
•        and the new curve only crosses the original curve once
•        and an attempt has been made to draw the new curve
correctly towards the energy axis but not to touch the
original curve
•        the new curve must not start to diverge from the original curve
M1 is low demand
M2 is higher demand.
2
   (ii)     M1    Increase in the number/proportion of molecules with E ≥ Ea
OR    more molecules have E ≥ Ea
OR    more molecules have sufficient energy to react
  M2    More effective/productive/successful collisions
Ignore “molecules have more energy”
Ignore “more energetic collisions”
Ignore “molecules gain activation energy”
Ignore “more collisions”
Accept “particles” for “molecules” but NOT “atoms”
Ignore “chance of collision”; this alone does not gain M2
2
(b)     (i)      Iron OR Fe
1
(ii)     M1    Catalysts provide an alternative route/pathway/mechanism
OR
(in this case) surface adsorption/surface reaction occurs.
For M1, not simply “provides a surface” alone
M2    that has a lower activation energy
OR
lowers the activation energy
For M2, the candidate may use a definition of activation energy without referring to the term
2
[7]
 
2.      (a)     Gradient (or slope) (or draw a tangent)
1
(b)     (i)      Curve X is lower and starts at origin
1
         And levels out at same volume as original curve
1
(ii)     Curve Y is steeper than original and starts at origin
1
         Then levels out at half the volume of the original
1
(c)     (i)      2H2O2 → 2H2O + O2
1
(ii)     Speeds up (alters the rate of) a chemical reaction
1
Remains unchanged (or not used up)
1
(iii)     Remains unchanged (or not used up or not in the
overall reaction equation)
1
         Offers alternative reaction route (or acts as an intermediate)
1
[10]

3.     (a)     (i)      acid            0.46
1
alcohol        1.46
1
water          5.54
1
(ii)     Kc = 
penalise ( )
allow molecular formulae or minor slip in formulae
1

(iii)     
Allow without V
Conseq on values in (a)(i)
If values used wrongly
or wrong values inserted
or wrong Kc              no marks for calc
1
4.45 or 4.5
Part (a)(iii) for info 0.46 × 1.46 = 0.6716
1
cancel (as equal no of moles on each side of equation)
1
Possible wrong answers
 
acid          0.46		Gives	
alcohol      1.46		Kc = 3.59	
water         4.46			

acid           0.46		Gives	
alcohol      1.46		Kc = 0.434	
water         0.54			

(b)     (i)      decrease or be reduced or fewer
1
(ii)     decrease or be reduced or less time or faster or quicker
1
(iii)     decrease or be reduced
1
[10]

4.    		     no change
1
equal number of gaseous moles on either side
1
both sides affected equally
1
increases
1
equilibrium moves to lower the temperature/oppose the change
1
endothermic reaction favoured /forward reaction is endothermic
1
 [6]
 
5.    (a)     T2
(Must be correct to score any marks in this section)
1
          Exothermic
1
Reduce T to shift equilibrium to the right
or forward reaction favoured by low T
or Kp increases for low T
or low T favours exothermic reaction
1
(b)     Increase
1
          None
1
[5]
 
6.              high pressure expensive (due to energy or plant costs)
1
(Rate is) slow (at lower temperatures)
1
[2]

 

7.	D
[1]
8.	D
[1]
9.	A
[1]
10.	C
[1]
11.	D
[1]
12.	A
[1]
13.	C
[1]
14.	D
[1]
15.	A
[1]
16.	C
[1]