Law of Conservation Flashcards
the scientific principle that matter is neither created nor destroyed during a chemical change.
Law of Conservation of Mass
a substance that is present at the beginning of a chemical reaction
Reactant
a substance that is produced during a chemical reaction
Product
a number written before a chemical formula to show how many atoms or molecules of that substance are involved in a reaction
Coefficient
a description of a chemical reaction using chemical formulas, subscripts, and coefficients
Chemical Equation
an open system is a system that can freely exchange matter and energy with its surroundings. An open system may appear to violate conservation laws because it can gain or lose matter and energy.
Open System
a system that cannot exchange matter or energy with anything outside it; No outside forces act on a closed system. Closed systems satisfy the law of conservation of energy and the law of conservation of momentum.
Closed System
Which BEST represents a balanced equation?
A. HgO —-> Hg + O2
B. 2Fe + O2 —-> Fe2O3
C. 2H2 + O2 —-> 2H2O
C. 2H2 + O2 —-> 2H2O
A 12 g sample of Mg reacts with 18 g of S. What mass of MgS is MOST LIKELY produced?
A. 6 g
B. 30 g
C. 60 g
D. 216 g
B. 30g
Which is the BEST system to use when studying the law of conservation of mass?
A. A closed system to measure the mass of the reaction
B. An open system to measure the mass of the reaction
C. A large system to give the reaction space to occur
D. A small system to closely observe the reaction
A. A closed system to measure the mass of the reaction
Which are conserved during a chemical reaction?
A. Mass and atoms
B. Volume and mass
C. Atoms and molecules
D. Molecules and volume
A. Mass and atoms
Which BEST describes a chemical reaction applying the law of conservation of mass?
A. An equation which uses energy
B. An equation which does not use energy
C. A balanced equation in which the reactants and products are equal
D. An unbalanced equation in which the reactants and products are unequal
C. A balanced equation in which the reactants and products are equal
If a student is chemically combining 4 g of H with 2 g of O, what will be the mass of the product?
A. 4 g
B. 6 g
C. 8 g
D. 10 g
B. 6 g
A chemical reaction occurs in a sealed test tube. As a result, 24 g of product are produced. Which is MOST LIKELY true?
A. The mass of the reactants was 24 grams
B. The mass of the reactants was less than 24 grams
C. The mass of the reactants was more than 24 grams
D. The mass of the reactants is not related to the 24 g
A. The mass of the reactants was 24 grams
Which products would balance the equation below?
CaCl2 + 2Li —->
A. LiCl + Ca
B. Li2Cl + Ca
C. 2LiCl + Ca
C. 2LiCl + Ca
How many copper atoms and chlorine atoms are in a molecule of CuCl2?
A. One copper atom, one chlorine atom
B. One copper atom, two chlorine atoms
C. Two copper atoms, one chlorine atom
B. One copper atom, two chlorine atoms
How does a balanced equation satisfy the Law of Conservation of Mass?
A. The total amount of mass stays the same
B. Matter is destroyed
C. One or more new substances are formed
D. The total number of atoms increases
A. The total amount of mass stays the same
Which is true of a chemical reaction?
A. Products and reactants must be balanced
B. Subscripts must be used with all products and reactants
C. Energy must be included in the beginning of the reaction
D. Coefficients must be used with all products and reactants
A. Products and reactants must be balanced
Which chemical reaction supports the law of conservation of mass?
A. H2O —-> H2 + O2
B. H2O —-> 2H2 + O2
C. H2O —-> H2 + 2O2
D. 2H2O —-> 2H2 + O2
D. 2H2O —-> 2H2 + O2
If a chemical reaction begins with 10 atoms of oxygen, how many atoms of oxygen should be in the products?
A. 10 atoms
B. 12 atoms
C. 6 atoms
D. 8 atoms
A. 10 atoms
Which is true of any physical or chemical reaction?
A. Mass increases
B. Mass decreases
C. Mass fluctuates
D. Mass is conserved
D. Mass is conserved
A compound with lithium and sulfur react with aluminum and iodine. Which BEST describes the elements in the products?
A. Lithium and iodine
B. Aluminum and sulfur
C. Aluminum, sulfur, and iodine
D. Lithium, sulfur, aluminum, and iodine
D. Lithium, sulfur, aluminum, and iodine
Ms. Davis has 100 g of Reactant X and 150 g of Reactant Y. After combining the two, how much product should she have?
A. 50 g
B. 100 g
C. 150 g
D. 250 g
D. 250 g
After a reaction, the mass of the products does not equal the mass of the reactants. What possibly happened to explain this?
A. The scale was not balanced
B. Some of the mixture spilled
C. Gas was produced and lost to the environment
D. Substances were added after the initial mass was recorded
C. Gas was produced and lost to the environment
The formula for glucose is C6H12O6. How many atoms of carbon should be present in the products if it is broken down chemically?
A. 1
B. 6
C. 12
B. 6
