Rate of reaction =measure rate and intro and collision theory
Transcript of Rate of reaction =measure rate and intro and collision theory
HOW TO DETERMINE RATE OF REACTION
FROM GRAPH
AVERAGE RATE OF
REACTION
INSTANTANEOUS RATE OF REATION
AVERAGE RATE OF REACTION
For the whole exp
From X
min to Y min
On the X min (2nd) ( from 2nd to 1st)
For first x
(3) min( from 0 to
3rd )
INSTANTANEOUS RATE OF REACTION
( rate of reaction at that time) Draw tangent to the
graph
Y
X
Rate = Y/X
b) Example from the graph, determine:i) The rate of reaction at 120 s
Instantaneous rate of reaction= Draw tangent to the graph
= 56 – 20 = 0.176 cm3 s-1
222-18
Changes to the graph
Changes to the CURVE part of graph
II
IIII
Volume of gas
Time
• Use positive catalyst• Increase temperature •Increase total surface area
Use negative catalyst
Decrease temperature
Decrease TSA
Changes to the FLAT part of graph
d) Curve I represents the result of the experiment using excess zinc powder and 50cm3 of 1.0 moldm-3 dilute hydrochloric acid
II
IIII
Volume of gas/ cm3
Time/s
• Use positive catalyst• Increase temperature of reactant
Lower concentration of hydrochloric acid
Collision theory
• Theory that explains how factors affect rate of reaction
• Before reaction can occur, particles must first collide
• Particles collide so that bonds are broken and new bonds can form
Collision theory
• Collision of particles must be effective collisions to produce result
• Effective collisions are collisions which – produce enough energy to overcome
energy of activation– correct orientation
Collision theory
• Activation energy is the minimum energy the colliding particles must overcome so that reaction occur
• In order for particles to overcome the activation energy, several factors involve
How factors affect rate of reaction according to collision theory
• Size of reactant for solid reactant• Temperature of reactant mixture• Concentration of solution reactant• Presence of catalyst
How Collision theory explain factor of size of solid reactant
• The smaller the size of reactant, the larger the total surface area
• Frequency of Collisions between particles increase
• Frequency of Effective collisions between particles increase
• Therefore rate of reaction also increase
How Collision theory explain factor of concentration
• The higher the concentration of reactant solution, the higher the number of particles per unit volume
• Frequency of Collisions between particles increase
• Frequency of Effective collisions between particles increase
• Therefore rate of reaction also increase
How Collision theory explain factor of temperature
• The higher the temperature of reactant solution, the higher the kinetic energy of particles
• Frequency of Collisions between particles increase
• Frequency of Effective collisions between particles increase
• Therefore rate of reaction also increase
Collision theory explain factor of catalyst
• Presence of catalyst provide an alternative path
• This alternative path has a lower activation energy
• More colliding particles can overcome this lower activation energy
• Frequency of Effective collisions between particles increase
• Therefore rate of reaction also increase