Chemical Reaction Lab Report - IPSE FPMIPA UPI Assignment
CHEMICAL REACTION
LAB REPORT
A.
Date
Tuesday, the 25th of October 2016
B.
Objectives
1. To
classify type of chemical reactions.
2. To identify chemical change characteristics.
C. Theoritical Background
Chemical changes
occur when bonds are broken and/or formed between molecules or atoms. This
means that one substance with a certain set of properties (such as melting
point, color, taste, etc) is turned into a different substance with
difference
properties. Chemical changes are frequently harder to reverse than physical
changes.
Observations
that help to indicate chemical change include:
1. Temperature
changes (either the temperature increases or decreases).
2. Light
is given off.
3. Unexpected
color changes (a substance with a different color is made, rather than just
mixing the original colors together).
4. Bubbles
are formed (but the substance is not boiling – you made a substance that is a
gas at the temperature as the
beginning materials, instead of a liquid).
5. Different
smell or taste.
6. A
solid forms if two clear liquids are mixed (look for floaties – technically
called a
precipitate).
In
a chemical change, new substances are formed. In order for this to occur, the
chemical bonds of the substances
break, and the atoms that compose them separate and rearrange themselves into
new substances with new chemical bonds. When this process occurs, we call it a
chemical reaction. A chemical reaction
is the process which one or more substances are changed into one or more new
substances.
Chemical reactions are classified
into types to help us analyze them and also to help
us predict what the products of the
reaction will be.
1.
Combination
Reactions
A Combination reaction is one in
which two or more reactants combine to make one type of product.
General equation: A + B →
AB
Combination reactions occur as a
result of two or more simpler elements or molecules combining to form a more
complex molecule. Look at the example below. Here two elements (hydrogen and
oxygen) are combining to form one product (water).
Example: 2 H2(g) + O2(g) → 2 H2O(l)
2.
Decomposition
Reactions
When one type of reactant breaks down
to form two or more products, we have a
decomposition reaction. The best way
to remember a decomposition reaction is that for all reactions of this type,
there is only one reactant.
General Equation: AB → A
+ B
Look at the example below for the
decomposition of ammonium nitrate to dinitrogen oxide and water.
Example: NH4NO3
→ N2O + 2 H2O
3.
Displacement
Reactions
In displacement reactions, one
element reacts with one compound to form products. The single element is said
to replace an element in the compound when products form. Metal elements will
always replace other metals in ionic compounds or hydrogen in an acid. Nonmetal
elements will always replace another nonmetal in an ionic compound.
General equation: A + BC
→ B + AC
Consider the following examples.
Zn(s) + Cu(NO3)2(aq)
→ Zn(NO3)2(aq) + Cu(s)
4.
Metathesis
Reactions
For metathesis reactions, two ionic
compound reactants will react by having the cations exchange places, forming
two new ionic compounds. The key to this type of reaction, as far as
identifying it over the other types, is that it has two compounds as reactants.
General equation: AB + CD
→ AD+ CB
For example, when solutions of silver
nitrate and sodium chloride are mixed, the following reaction occurs:
AgNO3(aq) +
NaCl(aq) → AgCl(s) + NaNO3(aq)
5.
Combustion
Reactions
In a combustion reaction, oxygen
reacts with another substance to produce carbon
dioxide and water. This is what happens
when fuel burns. Combustion
reactions usually have the same products, CO2 and H2O, and one of its reactants
is always oxygen. In other words, the only part that changes from one
combustion reaction to the next is the actual hydrocarbon that burns. The
general equation is given below.
General equation: CxHy
(hydrocarbon) + O2 → CO2 + H2O
Look at the reaction for the
combustion of octane, C8H18, below. Octane has 8 carbon atoms hence the prefix
“oct”.
Example: 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
D.
Materials
and Apparatuses
§ Materials
:
1. Zn, Cu, Mg wires
2. K₂CrO₄ solution
3. HCl solution
4. CuCO₃
solid
5. Ca(OH)₂
solution
6. Pb (NO₃)₂ solution
§ Apparatuses
:
1. Beaker glass 8. Stand
2. Test tube holder 9. Graduated cylinder
3. Spatula 10. Matches
4. Crucible tongs 11. Pipette
5. Test tubes 12. Rubber Stopper
6. Sand paper 13. Methylated Burner
7. Clamps 14. Glass tube
E.
Procedure
and Observation
|
No. |
Procedure |
Observation |
|
1. |
§ A
piece of copper and magnesium wire are scrubbed until they are shiny. § The
copper wire is held using crucible tongs, it’s placed in the hottest part of
a burner flame for 1-2 minutes. § The
change and appearance caused by burning are noted. (Magnesium wire is done
with the same procedure). |
§ The copper
and magnesium wires become shiny after it was scrubbed. § When
the magnesium is burned, it’s bit a white light and there are also some
sparks, it is melted and burned into black-white ashes. § When
the copper is burned, it changes color from orange to black, however it doesn’t
melt. |
|
2. |
§ 5 mL
of 1 M HCl(aq) is poured into a dry tes tube. A small piece of
zinc metal is added into the acid. § The
change and appearance are noted. § A
quantity of gas resulted is collected into a test tube containing water using
one-hole rubber and gass tube. (Mg wire is used to do the same procedure). |
§ The
small piece of Mg metal is dissolved into the HCl, it generates gas (proved by the existence of bubbles in the
other tube). When the experiment is conducted, the HCl solution radiates
heat. § The
small piece of zinc metal is not dissolved into the HCl but there are some
bubbles on it surface. However, there is no bubbles in the other tube. |
|
3. |
§ 2 mL
K2CrO4(aq) is poured to a test tube. § 10
drops of Pb(NO3)2(aq) are added to the test tube. § The
result is observed and noted. |
§ When
the Pb(NO3)2 is added into K2CrO4,
it generates a precipitate and it stays on the bottom of the test tube. |
|
|
§ 2
spatulas full of CuCO3 are placed in a large test tube. It covered
using a one-hole rubber stopper. The glass tube is inserted into the stopper. § 5 mL
of limestone Ca(OH)2 is placed into a small test tube. It is
connected to the test tube containing CuCO3. § The
test tube containing CuCO3 is heaten. The change and the
appearance is noted. |
§ When
the CuCO3 is being heaten, it’s slowly changes color from green to
black. While on the other test tube, the Ca(OH)2 solution become
turbid, bubbles are also founded there. |
F.
Data Analysis
§ Procedure
1
The
balanced equation that occurs: 2 Mg(s) + O2(g) → 2 MgO(s)
Reactans:
Mg(s) and O2(g)
Products:
MgO(s)
§ Procedure
2
The
balanced equation that occurs: Zn(s) + 2 HCl(aq) → ZnCl2(aq)
+ H2
Reactans:
Zn(s) and HCl(aq)
Products:
ZnCl2(aq) and H2
§ Procedure
3
The
balanced equation that occurs: K2CrO4(aq) + Pb(NO3)2
→ PbCrO4(s) + 2 KNO3
Reactans:
K2CrO4(aq) and Pb(NO3)2
Products:
PbCrO4(s) and 2 KNO3
§ Procedure
4
The
balanced equation that occurs: CuCO3(s) → CuO(s) + CO2(g)
Reactans:
CuCO3(s)
Products:
CuO(s) + CO2(g)
The
balanced equation that occurs: Ca(OH)2(aq) + CO2(g) →
CaCO3(s) + H2O(l)
Reactans:
Ca(OH)2(aq) and CO2(g)
Products: CaCO3(s) and H2O(l)
G.
Discussion
§ In
the first lab the magnesium reacted with the flame by producing magnesium
oxide. This is an example of combination. It follows the synthesis formula of A + B → AB or (in the case of the lab) 2Mg
+ O2 → 2MgO. We can always identify a combination reaction because there
is only one product of the reaction. The chemical change characteristic that
occur in this case is the color changes of Mg (into black-white ashes) and Cu
(from orange into black).
§ Based
on the theoritical background, the second lab is a type of displacement
reactions because when one element trades places with another element in a
compound which is based on General equation: A + BC → B + AC (in the case of
the lab) Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2.
The chemical change characteristic that occur in this case is conducted bubbles
so it is forming the hydrogen gas.
§ In
the third lab is an example of metathesis reaction because two ionic compound
reactants will react by having the cations exchange places, forming two new
ionic compounds. It follows to the formula AB + CD → AD+ CB (in the case of the
lab) K2CrO4(aq) + Pb(NO3)2 → PbCrO4(s)
+ 2 KNO3. The chemical change characteristic that occur in
this case is precipitate, which is stays on the bottom of the test tube.
§ Based on the theoritical background, the fourth lab is a type of decomposition and metathesis reaction. This could be classified based on the formula of decomposition AB → A + B (in the case of the lab) CuCO3(s) → CuO(s) + CO2(g). The best way to remember a decomposition reaction is that for all reactions of this type, there is only one reactant. Also the formula of metathesis formula AB + CD → AD+ CB (in the case of the lab) Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l). Metathesis reaction could be formed because when the anions and cations of two different molecules switch places, forming two entirely different compounds. The chemical change characteristics that occur in this case are the changes colour and conducted the bubbles.
H.
Conclusion
The experiment is about chemical reaction which is succeeded proved us the type of chemical reaction and chemical change characteristics based on the theoritical background. Many kinds of chemical reaction in our life so we can directly observed it in laboratory activity which can make us to classify the type of reaction and determine the chemical change.
I.
References
Poulsen, Tracy. 2010. Introduction to Chemistry. United States: Create Space.
0 Response to "Chemical Reaction Lab Report - IPSE FPMIPA UPI Assignment"
Posting Komentar