JAWAPAN / SCHEM MODULE CHEMISTRY WAJA-CHAPTER 1-RATE OF REACTION

ANSWER

Activity
1	speed , product reactants , products
2	1. S              2. S               3. F             4. S             5. F 6. F              7. S               8. S             9. S           10. F
3	decrease ,     increase,       increase,           forming
	Eq 1 :          CaCO3  +  2HCl  →  CaCl2  +  CO2  +  H2O Changes : - decrease in the mass of CaCO3 - increase in volume of CO2 released Eq 2 :      Na2S2O3  +  H2SO4  →  Na2SO4  +  SO2  +  S  +  H2O Change : time taken for the yellow precipitate of sulphur formed Eq 3 :      2H2O2  →  2H2O  +  O2 Change : increase in the volume of oxygen gas
4	4A	2(a)  V4      ;    V2     ;      V3  - V2  ;  60  ;  V3  - V2          240         120                                      60 2(c)  V2  - V1             160 - 30
	4B	1 Plot a graph
		2 (i)  Average rate of reaction  ,   V    =    86    =  28.67 cm3min-1      in the first 3 min                    t            3 (ii)         V  =  V3 – V2  =  86 – 70    =  16                t   =    t3 – t2      =  3.0 – 2.0  =  1.0                  Average rate of reaction    ,    V   =  16   =   16  cm3min-1                              In the third min          t       1.0 (iii)       V  =  total volume of gas collected at 4.0 min (95 cm3)              t  =  time taken for the reaction to be complete =  4.0 min             Overall average rate of reaction , =  V   =  95   =   23.75  cm3min-1                                                                       t        4.0 (iv)        Show a tangent  at the 1 min of the graph              The instantaneous rate of reaction  at 1 min              =  gradient of the curve at 1 min              =  Y2 – Y1          =   70 – 30    =  40  =  26.67  cm3min-1                  X2 – X1              1.55 – 0.5      1.5
5	1	(a)  (i)      Average rate of reaction in the first 10 sec =   20     =  2   cm3 s-1                       10 (ii)           Average rate of reaction in the first 30 sec =    46     =  1.53    cm3 s-1                        30 (iii)          Overall average rate of reaction =    50     =   1.25     cm3 s-1                   40
		(b) The rate of reaction decrease with time. (c)  This is because the concentration of       hydrochloric acid, HCl decreases. When there is no more hydrochloric acid,       HCl remaining, the reaction is complete and the rate of reaction is zero.
	2	(a) the first 60 seconds     =   29  -  17    =  12        =    0.4  cm3s-1                                                                                                        60 -  30         30                                                                                                                                                                                                                          (b) the overall reaction        =     36        =   0.3   cm3s-1                                                   120
	3	0.0036 g min-1
6	(a) (b) (c) (d) (e)	The size of solid reactant/ Total surface area of solid reactant Temperature Concentration of reactant Presence of catalyst Pressure of gaseous reactant
7	1 2 3 4 5 6 7 8	√ Temperature X √ Concentration √ Size of reactant X √ Presence of catalyst √ Pressure X
8	(i)	CaCO3  +  2HCl  →  CaCl2  +  CO2  +  H2O Steeper Higher Larger/bigger, higher
	(ii)	Na2S2O3  +  2HCl → 2NaCl + S  + H2O  +  SO2. Shorter The rate of reaction Higher ,  higher
	(iii)	2H2O2  →  O2  + 2H2O Steeper Higher Increase
	(iv)	Na2S2O3  +  2HCl → 2NaCl + S  + H2O  +  SO2. Shorter The rate of reaction Higher , higher
9	1	low (-30 – 10oC) ,  active ,  toxic ,  lower.
		high (25 – 40 oC)  ,  more  ,  lot of ,  higher
	2	smaller ,   smaller  ,  total surface area,   higher
	3	(i) ammonia ,  N2  +  3H2  ↔  2NH3 ,   450 – 550oC ,  200 – 400 atm,  iron (ii) contact ,  2SO2  +  O2  ↔  2SO3  ,  450 oC  ,  1 atm  ,  vanadium(V) oxide
10	1	(i) collision between  particles (ii) effective collisions (iii) activation energy
	2	(i) collide (ii) product (iii) effective ,  activation energy
	3	Minimum
	4	Reactant
11		Ea : Activation energy Ea’ : Activation energy in the presence of catalyts
12	(i)	total surface area ,  larger   ,  increases  ,   increase  ,  higher
	(ii)	lower , incrases , higher
	(iii)	kinetic energy  ,  faster   ,  increase ,  more  ,  increasing of   , higher
	(iv)	increase  , number  ,  increases  , increases , higher
13	1 2	Volume of hydrogen gas /cm3   Volume of hydrogen gas /cm3                                                                                       Time (s)   55
14	1 2	(a) Zn  +  H2SO4  →  ZnSO4  +  H2 (b) Overall average rate of reaction  =  210     =  ……………. cms-1                                                               150 (c) (i)      (ii) [Draw a tangent at 80 s] [Rate of reaction  =  gradient of the tangent] (d) The decreasing of the mass of zinc used. (i) higher ,  higher  ,   higher ,  collision  ,  increases  ,  effective  ,  higher. (ii) higher ,  bigger.larger ,  collision,    increases , effective ,  higher.