Pre-Laboratory Question: Investigating Chemical Reactions Balance each of the fo
ID: 933302 • Letter: P
Question
Pre-Laboratory Question: Investigating Chemical Reactions
Balance each of the following equations, and classify each of the reactions by type.
Reaction Equation
Type of Reaction
1.
KClO3
KCl
+
O2
2.
Na
+
O2
Na2O2
3.
KI
+
Pb(NO3)2
KNO3
+
PbI2
4.
Cu
+
AgNO3
Cu(NO3)2
+
Ag
5.
C3H8
+
O2
CO2
+
H2O
+
Heat
6.
Zn
+
HCl
ZnCl2
+
H2
Laboratory Questions
Activity 1: Synthesis Reaction
Describe all of the signs that indicated a chemical reaction occurred.
Describe the temperature change that occurred during this reaction. Is heat required or produced during the reaction?
Describe any other changes that were observed in the steel wool. What reaction might create such a change?
Write a balanced equation for the reaction of the steel wool with oxygen. Be sure to include heat energy in the reaction.
Activity 2: Decomposition Reaction
What gases could be produced from decomposing hydrogen peroxide?
Which gas was produced?
Write a balanced equation for the decomposition of hydrogen peroxide.
Activity 3: Single-Replacement Reaction
What gases could be produced from hydrochloric acid (HCl)?
Which gas was produced?
Write a balanced equation for the reaction of magnesium with hydrochloric acid.
Why did you need to tilt the splint at a 45-degree angle?
a. Write a balanced equation for the reaction initiated by the burning splint.
b. Classify the reaction initiated by the burning splint.
Activity 4: Double-Replacement Reaction
Describe the reaction of sodium bicarbonate and vinegar.
Refer to the section in the Background titled, “Standard Tests Gaseous Products.” Use a flaming splint and a glowing splint to identify the gas above the liquid in the cup. Write the name and formula of the gas in the space provided.
Write a balanced chemical equation for this double-replacement reaction.
One of the two products of this reaction is carbonic acid (H2CO3), which immediately forms water and the gas you identified after exposure to the flaming and glowing splints. Write a balanced equation showing the decomposition of carbonic acid.
Activity 5: Combustion Reaction
Explain why water appears on the inside of the glass test tube.
Write a balanced equation for the combustion reaction.
Activity 6: Precipitation Reaction
Write a balanced equation for the precipitation reaction.
Which product in the above reaction is the precipitate?
Discussion Questions
Predict the product(s) of the following equations. Balance the equations, and classify each of the reactions by type.
Equation
Type of Reaction
1.
Pb(NO3)2 + Na2CO3
2.
C4H10
+
O2
3.
Zn + CuSO4
4.
CaCO3
Heat
5.
Na
+
H2O
6.
Ca
+
O2
7.
MgSO4
+
LiOH
8.
Al
+
NiSO4
9.
SO2 + H2O
10.
HgO
Heat
Reaction Equation
Type of Reaction
1.
KClO3
KCl
+
O2
2.
Na
+
O2
Na2O2
3.
KI
+
Pb(NO3)2
KNO3
+
PbI2
4.
Cu
+
AgNO3
Cu(NO3)2
+
Ag
5.
C3H8
+
O2
CO2
+
H2O
+
Heat
Explanation / Answer
Answers for Balanced equations and classification of each of the reactions by its type.
2 KClO3 (s) --------> 2 KCl (s) + 3O2 (g)…………………………………….Decomposition Reaction
2 Na (s) + O2 (g) --------> Na2O2 (s)…………………………………………Synthesis Reaction
2 KI (aq) + Pb(NO3)2 (aq) --------> 2 KNO3 (aq) + PbI2 (s)…………….. ...Double-Replacement Reaction
Cu(s) + 2 AgNO3 (aq) --------> Cu(NO3)2 (aq) + 2 Ag (s)………………. ...Precipitation Reaction
C3H8 (g) + 5 O2 (g) --------> 3 CO2 (g)+ 4 H2O (g) + Heat……………… ..Combustion Reaction
Zn (s) + 2 HCl (aq) --------> ZnCl2 (aq) + H2 (g) ………………………….. Single-Replacement Reaction
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Answers for Laboratory Questions:
Activity 1: Synthesis Reaction:
Reaction of steel wool with oxygen.
A large amount of heat is supplied by burning pure oxygen and then steel wool burns and changes to iron oxide. Following is the balanced equation of the reaction.
4 Fe (s) + 3 O2 (g) ==> 2 Fe2O3 (s)
Activity 2: Decomposition Reaction:
Oxygen is produced in the decomposition reaction of H2O2. Below is the balanced equation of the decomposition of H2O2:
2H2O2 (l) =======> 2H2O (l) + O2 (g)
Activity 3: Single-Replacement Reaction:
Balanced equation for the reaction of magnesium with hydrochloric acid
Mg (s) + 2 HCl (aq) --> MgCl2 (aq) + H2 (g)
As can be seen from the above equation hydrogen is produced upon reaction of magnesium
metal with hydrochloric acid.
Holding splint at 45o is important as it allows better supply of oxygen for the burning splint.
The reaction initiated by the burning splint can be classified as combustion reaction.
Activity 4: Double-Replacement Reaction
Na2CO3 (aq) + 2 CH3COOH (l) ------> 2 CH3COO-Na+ (aq) + H2CO3 (g)
H2CO3 (g) ---------> H2O (l) + CO2 (g)
The final gas generated upon reaction of sodium carbonate with vinegar (acetic acid) is carbon
dioxide and extinguishes the burning wooden splint.
Activity 5: Combustion Reaction
Example for a combustion reaction:
C3H8 (g) + 5 O2 (g) --------> 3 CO2 (g)+ 4 H2O (g) + Heat
A combustion reaction uses oxygen to burn the fuel and emits carbon dioxide gas and water
vapour. This is the reason for appearance of water on the inside of the glass test tube.
Activity 6: Precipitation Reaction
The following reaction is an example for precipitation reaction from the above reactions.
2 KI (aq) + Pb(NO3)2 (aq) --------> 2 KNO3 (aq) + PbI2 (precipitate)
Answers for Discussion Questions:
1. Pb(NO3)2 (aq) + Na2CO3 (aq) ----- PbCO3(s) + 2 NaNO3 (aq) ………......Precipitation Reaction
2. 2 C4H10 (g) + 13 O2 (g) ---------------> 8 CO2 (g)+ 10 H2O (l)+ Heat…..........Combustion Reaction
3. Zn(s) + CuSO4 (aq) --------------> ZnSO4 (aq) + Cu (s) ………………….....Redox Reaction
4. CaCO3 (s)+ Heat ------------> CaO (s) + CO2 (g)...………………………….....Decomposition Reaction
5. 2 Na (s) + 2 H2O (l) ----------------> 2 NaOH (aq) + H2 (g).………………........Combustion Reaction
6. 2Ca (s)+ O2 (g)----------------------> 2CaO (s)……………………………….......Combustion Reaction
7. MgSO4 (aq) + 2 LiOH(aq)---> Mg(OH)2 (s) + Li2SO4 (aq) ……...…................Double-Replacement Reaction
8. 2 Al (s)+ 3 NiSO4 (aq) ------------------> Al2(SO4)3 (aq) + 3 Ni(s)……...............Redox Reaction
9. SO2 (g)+ H2O (l)-------------------> H2SO3 (aq) …………………………………...Synthesis Reaction
10. 2HgO (s) + Heat --------------> 2Hg(l) + O2 (g)………………………………….....Decomposition Reaction
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