Chemical Change
Chemical Equations
Balancing equations (double score)
Producing useful Materials
Problems
100
From the choices select what is NOT an evidence of chemical change
a) Color change
b) Precipitate formation
c) Temperature change
d) Gas production
c) Temperature change
100
From the following chemical equation. Which are the reactants?
KMnO4 + HCl ------> KCl + MnCl2 + H2O + Cl2
KMnO4 + HCl
100
(1 min) Balance the following equation.
- K + Cl2 ---> KCl
- 2 K + Cl2 ---> 2 KCl
100
A pure substance is defined as:
a) A substance that comes from nature
b) A substance that is not mixed with other substances
c) A substances that has only one chemical element
b) A substance that is not mixed with other substances
200
Why a chemical reaction happens?
a) Because new matter is produced
b) Because new atoms are produced
c) Because new substances are produced
d) Because energy is produced
c) Because new substances are produced
200
From the following chemical equation. Which are the products?
- CuSO4 + 5 H2O -----> CuSO4 + H2O
CuSO4 + H2O
200
(2 min) Balance the following equation.
- CaCl2 + H2 ---> HCl + Ca
- CaCl2 + H2 ---> 2 HCl + Ca
200
A main advantage of a pure medicine is that it:
a) Works better
b) Is less likely to produce side effects
c) Is easier to obtain from nature
d) Is more natural
b) Is less likely to produce side effects
200
On the following graph. Pick the curve that corresponds to a reaction with a Catalyst
Red curve
300
A chemical reaction that releases energy is an ____________ while another that absorbs energy is an _____________
Exothermic - Endothermic
300
For the following equation, complete with the product that is left from among the choices:
- C6H5COOH + O2 ------> CO2 + _____
a) NO2
b) HCl
c) H2O
d) CCl4
c) H2O
300
(5 min) Balance the following equation.
- KMnO4 ---> Mn + K2O + O2
- 4 KMnO4 ---> 4 Mn + 2 K2O + 7 O2
300
It is defined as the unit of a polymer
Monomer
300
On the following graph. Pick the letter that corresponds with the activation energy of catalized a chemical reaction
B
400
In order to accelerate the rate of a reaction you can (pick the two sentences that apply):
a) Increase the temperature
b) Add a catalyst
c) Decrease the surface area
d) Decrease the temperature
a) Increase the temperature
b) Add a catalyst
400
A _______ reaction is a sealed system that keeps matter trapped
Closed System
400
(5 min) Balance the following equation.
K4Fe(CN)6 + H2SO4 + H2O ---> K2SO4 + FeSO4 + (NH4)2SO4 + CO
K4Fe(CN)6 + 6 H2SO4 + 6 H2O ---> 2 K2SO4 + FeSO4 + 3(NH4)2SO4 + 6 CO
400
Calculate the right amount of atoms for each element at the following formula
AgCl2(NH3)2
Ag: 1, Cl: 2, N: 2, H:6
500
Is the amount of energy necessary to begin a chemical reaction.
Activation Energy
500
Relate the following reactions with its correct classification.
a) Synthesis b) Decomposition c) Replacement
1. 2 Fe + 3 Cl2 --> 2 FeCl3
2. Cr2O7 + 7 H2 ----> 2 Cr + 7 H2O
3. H2CO3 ----> CO2 + H2O
1. a, 2. c, 3. b
500
(5 min) Balance the following equation:
- C6H5COOH + O2 ----> CO2 + H2O
- 2 C6H5COOH + 15 O2 ----> 14 CO2 + 6 H2O