ADAPTIVE TEACHING GUIDE
Most Essential Topic #4
Lesson : Rates of Reaction
Pre-requisite Content Knowledge: Collision Theory / Chemical Reaction
Pre-requisite Skills:
● Explain Collision Theory
● Differentiate reactants from products in a chemical reaction
Pre-requisiteAssessment: Modified True or False
Pre-lesson Remediation Activity:
For students with Insufficient Level on Prerequisite Content-knowledge and/or Skill(s):
● Exercises on Collision Theory/ Chemical Equation.
For students with Fairly Sufficient Level on Prerequisite Content-knowledge and/or Skill(s):
● Reading material/video
Introduction:
The learners will about to learn Lesson #1 in Most Essential Topic #2 which is the Rate of Chemical Reaction. They are expected to finish in learning the lesson in One
and a half hours which is equivalent to one session. If they have concerns related to the lesson they may contact me through email, chat, direct message, text or call
or set an appointment for consultation face to face.
In learning the topic, they are expected to explain the effects of temperature, particle size, and concentration through Collision Theory and the effect of catalysts in a
chemical reaction.
Upon learning the lesson, the learners can apply it in doing their mini task 1 (EFAA #1). Moreover, practical applications of the concepts are experienced in their day-to-
day activities like cooking, using household substances and personal care products, and other similar activities.
The rate of reaction is the speed at which the reactants are converted into products. For a chemical reaction to occur, molecules, atoms, or ions must collide. To achieve
effective collisions, particles must possess the minimum amount of energy needed for the reaction and must collide with proper orientation. The chemical reaction
varies. Some chemical reactions happen so fast, while others take some time to reach equilibrium. This lesson helps them explore the factors affecting the rate of
reaction.
Students’ Experiential Learning
As the learners start the lesson, let them answer the questions found in the table below. Let them write their answer in the first column (Initial).
INITIAL REVISED FINAL
1.Why do we keep
most foods in the
refrigerator?
2.Why is
highly
concentrat
ed
medicationdeadly?
As they continue learning the concept, they may go back to their initial answer and may revise their answer or not. If their initial answer needs revision, then they may
fill-in the second column. If their revised answer is the final answer, then just copy it in the third column, if not then they will write their final revision on the third
column.
The learners may recall/review the Collision Theory. This theory states that for reactions to occur, molecules, atoms, or ions must first collide. Not all collisions are successful.
For collisions to be effective collisions, particles must possess the minimum amount of energy needed for the reaction and must collide with proper orientation. No reaction
will take place between two particles if they are far apart. These particles must come in contact with each other with proper orientation to break the bonds of
atoms to form new bonds. However, not all colliding particles react and form products even if they have the proper orientation. Like a candle does not burn
spontaneously even in the presence of oxygen. It needs a flame to start to burn. This suggests that the reacting
particles do not just collide but must have sufficient energy to break the bonds in the reactants and begin to form the bonds in the products. We are going to use this
Collision Theory to explain the factors affecting the rate of reaction. The rate of reaction here has something to do with the time for the reaction to occur. There
are several factors that affect the reaction rates. These factors are the Concentration, Particles Size, Temperature and Catalyst.
Concentration
Based on their experience, substances with higher concentrations have more particles available for collision. If there are more collisions, then more products would also be
formed at a certain
period.
Generally, the higher the concentration of the substance, the faster the rate of reaction.
Particle Size
The Particle Size of a substance also affects the rate of a chemical reaction. Comparing the effect of adding a clump of sugar and refined sugar to a cup of water,
learners may notice that the refined sugar would react at a faster rate than the clump of sugar with the molecules of water. This is because the surface area in contact is
greater as the size of the particles decreases. Surface area refers to how much of the particle is exposed. The bigger the surface area the more collisions between
particles will happen. The more collisions, the faster the rate of reaction.
Temperature
Next to Particle Size is Temperature. The temperature of a substance greatly affects the speed of reaction. If the temperature is increased, the rate of reaction also
increases. The molecules of a
substance become more active as the temperature increases. If the molecules are more active, then there would be more collisions between the molecules. The more
collisions, the faster is the rate of reaction.
Catalysts
Finally, we have the catalyst. The chemical reaction varies. Some reactions happen very slowly. Sometimes it would take hours and days or even more to complete such
reactions. This is the reason why catalysts are added to the reacting substances. A catalyst is a substance that speeds up the rate of reaction. However, it is not
affected by the reaction. Although it may alter the reaction, it can be recovered after the process. The catalyst lowers the activation energy required so that the
molecules of the reactants can already start colliding with each other.
After knowing the four factors affecting the rate of chemical reaction, ask the learners to explain the effects of concentration, temperature, and particle size on the
rate of reaction using the collision theory. Also, ask them to explain how a catalyst affects the reaction rate.
Check Your Understanding! (Use the Collision theory to explain the effects)
Scenario # 1: Muriatic acid is known to be a cleaning agent. It removes stains in tiled surfaces. Let us say you are asked by your mother to clean your stained lavatory
with Muriatic acid. Now, how are you going to apply the muriatic acid to remove the stain from the lavatory effectively? Are you going to dilute the muriatic acid
with water before application or not? Why?
Scenario # 2: You are preparing your hot chocolate drink. On your table you have powdered and cubed chocolate. Which chocolate are you going to use and why?
Question # 1: Why do we keep most foods in the refrigerator?
Question # 2: What are the roles that enzymes play in our body? Give a specific enzyme and its role.
Enrichment Activity!
Predict the reaction rate (Faster/Slower/thesame) and the factor affecting the rate of reaction in the following.
Assume that the substances below are reactants for different reactions. Indicate if the reaction will be slower, faster, or have the same rate.
Normal condition Changed condition Factor Reaction rate
a) 20 % HCl 5 % HCl
b) 276 K 315 K
c) 2H2O2 → 2H2O + O2 addition of iron (III) oxide
d) A cube of sugar powdered sugar
e) 5 sampalok cubes 1 sampalok cube
f) 52 g of NaOH 65 g of NaOH
g)3.68 x 1025 atoms of Li 9.25 x 1023 atoms Li
h) 500 K, 4.5% Barium 600K, 4.5% Barium
i) 48 g powdered zinc 48 g zinc pellets
j) Starch + water Starch + water + amylase
