EXPERIMENT NO. 5
GROUP NO. 2
LEADER: TARA FAYE BAYAS
ANN MARJORY V. CARIÑO
PEARLY RUBY CARIAGA
KRISTINE GRACE CORTEZ
JULIUS BRYAN CRUZ
Chemical reaction may proceed with a net
absorption of energy or with a net release of heat.
The energy transaction may include heat, light or
‘exothermic’ refer to the heat exchange only.
The word endothermic ("within-heating") describes a
process or reaction in which the system
absorbs energy from the surroundings in the form
of heat. Its etymology stems from the prefix endo(derived from the Greek word ένδον, endon, "within")
and the Greek word thermasi, (meaning “to heat”).
The opposite of an endothermic process is
an exothermic process, one that releases energy in the
form of heat. The term endothermic was coined
by Marcellin Berthelot.
Expressed in a Chemical Equation:
Energy + Reactants → Products
reactants have less potential energy
Energy must be input in order to raise the
particles up to the higher energy level.
Photosynthesis is an example of an endothermic
reaction. The chlorophyll and pigments in the plant
absorb the light energy from the sun's rays, as
endothermic reaction is that in which energy is
is a chemical reaction that
releases energy in the form of light
or heat. It is the opposite of an
Expressed in a chemical equation:
reactants → products + energy
reactants have more potential energy
than the products have.
extra energy is released to the
EXAMPLE OF EXOTHERMIC REACTION
Explosions are examples of exothermic reactions
as they release energy to their surroundings.
To determine the energy changes that
occur during a certain type of chemical
Graduated Cylinder, 50 mL
1.5 M Citric acid
2 M HCL
Reacting Citric Acid and Baking Soda
1. Part II
Place a 150 mL- beaker into the calorimeter as shown in the diagram.
Put 30 mL of 1.5 M citric acid into the beaker. Place the temperature
sensor into the citric acid solution. Click on “REC” button to begin
Weigh out 10.0g of baking soda on a piece of weighing paper. After
about 20 seconds have elapsed, add the baking soda to the citric acid
solution. Gently stir the mixture to ensure complete reaction
Allow the computer to record data until a minimum temperature has
been reached and temperature readings begin to increase or let the
computer automatically end it after 250 seconds.
Dispose the reaction products and rinse the cup.
Reacting Magnesium and Hydrochloric Acid
Repeat Procedure A using magnesium ribbon ( 5 cm long) instead of
baking soda and hydrochloric acid in place of citric acid 1.5 M.
HCL + Mg ribbon
Citric acid + Baking
Run no. 1
Data from: Gr. 4
1. What type of energy change is associated with
the chemical reaction between Citric Acid and
-chemical change .Endothermic Reaction
With magnesium and Hydrochloric Acid
-Heat energy. Exothermic Reaction
2. How do the experimental data support the
energy changes described?
-Through the heat that we applied , some of the
chemicals that we mixed
3.What does a negative T value indicates?
- it indicates into a colder region and it means that the
temperature goes down. Therefore the endothermic
reaction took place.
4.Described 3 ways to determine that chemical reaction
has taken place.
- when the experiment has taken place. The
experimental take reaction/ then it bring into a
Change in color
Change in odor
Change in temperature
Release of gas
5. Which reaction took place at a greater rate?
The Exothermic Reaction ( Magnesium Ribbon
and the Hydrochloric Acid ).
- Shows higher temperature .