Worksheets8.P.1.4 Review
Total questions: 20
Worksheet time: 20mins
One molecule of carbon dioxide (CO2) combines with one molecule of water (H2O) to make one molecule of carbonic acid. According to the Law of Conservation of Mass, how many atoms of carbon should be in the carbonic acid?
1
2
3
How many copper atoms and how many chlorine atoms are in a molecule of CuCl2?
one copper atom, one chlorine atom
one copper atom, two chlorine atoms
two copper atoms , one chlorine atom
A chemistry student combines 32 grams of one chemical and an unknown amount of another chemical in a closed system. A chemical reaction occurs and the mass of the products is 114 grams. How much of the unknown chemical was used in the reaction?
32 grams
82 grams
114 grams
What is the importance of a closed container in a chemical reaction?
to observe the mass before and after the reaction occurs
to keep any materials from interfering with the reaction
to observe the loss of mass after the reaction occurs
Which best represents a balanced equation?
Mg(s) + 2O2(g) 2MgO(s)
Mg(s) + O2(g) 2MgO(s)
2Mg(s) + O2(g) 2MgO(s)
Which best supports the Law of Conservation of Mass?
Atoms can be rearranged to keep the same mass.
Atoms can be destroyed to make a new substance.
Atoms can be rearranged to change their mass.
Which must be true if the number of atoms stays the same regardless of how they are arranged?
Their total mass must change.
Their total mass stays the same.
An open system must have been used.
The compound ammonia is composed of nitrogen and hydrogen atoms. If two atoms of nitrogen completely react with six atoms of hydrogen to form two molecules of ammonia, which best describes the number of hydrogen atoms present in the two molecules of ammonia?
two hydrogen atoms
four hydrogen atoms
six hydrogen atoms
When chemicals react in a closed container, which must be true?
The mass both before and after the reaction is the same.
The mass both before and after the reaction is variable.
The same number of compounds is present both before and after the reaction.
Which is the correct way to balance the chemical equation shown below?
Al + O2 → Al2O3
2Al + O2 → Al2O3
2Al + 3O2 → Al2O3
4Al + 3O2 → Al2O3
4Al + 3O2 → 2Al2O3
Which best explains how the chemical reaction shown below follows the law of conservation of mass?
2H2 + O2 → 2H2O
The hydrogen and oxygen molecules combine to form water.
Hydrogen and oxygen are held together by strong chemical bonds.
There are hydrogen and oxygen atoms on both sides of the equation.
The same number of hydrogen and oxygen atoms are on both sides of the equation.
What is the total number of oxygen atoms on the reactant side of the equation shown below?
CH3COOH + NaHCO3 → CH3COONa + H2O + CO2
2
3
5
7
A chemical reaction is represented by the equation below.
BeO + 2NaCl → Na2O + _______
Which substance would make the equation true and balanced?
BeO
BeCl2
Be2Cl
Which products would balance the equation below?
CaCl2 + 2Li →
LiCl + Ca
Li2Cl + Ca
2LiCl + Ca
Which best represents a balanced equation?
120 grams of carbon plus 20 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 50 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 80 grams of oxygen → 200 grams of carbon dioxide
In the equation below, suppose 11 grams of zinc react with 12 grams of hydrogen chloride to form 16 grams of zinc chloride and an unknown amount of hydrogen gas.
Zn + 2HCl → ZnCl2 + H2
Based on the Law of Conservation of Mass, how many grams of hydrogen gas will form?
1 gram
7 grams
19 grams
Which best explains why the total mass of the product(s) would be less than the total weight of the reactant(s) after a chemical reaction?
A physical change occurred.
Atoms involved in the reaction lost mass.
Precipitates were created in the new solution.
Gases were released to the atmosphere.
How does a balanced chemical equation satisfy the Law of Conservation of Mass?
During a chemical reaction, the total amount of matter stays the same.
During a chemical reaction, matter is destroyed.
During a chemical reaction, one or more new substances are formed.
During a chemical reaction, the total number of atoms increases.
Which set of coefficients will balance this chemical equation?
__PbS(s) + __O2(g) → 2PbO(s) + 2SO2(g)
1, 2
1, 3
2, 3
2, 5
Which best represents a balanced equation?
HgO --> Hg + O2
2Fe + O2 --> Fe2O3
2H2 + O2 --> 2H2O
