Chemical Equations

Knowledge about what products are produced in a chemical reaction is obtained by:

A. Inspecting the chemical equation
B. Balancing the chemical equation
C. Laboratory analysis
D. Writing a word equation

C. Laboratory analysis

Which observation does NOT indicate that a chemical reaction has occurred?:

A. Formation of a precipitate
B. Production of a gas
C. Evolution of heat and light
D. Change in total mass of substances

D. Change in total mass of substances

A solid produced by a chemical reaction in solution that separates from the solution is called:

A. A precipitate
B. A reactant
C. A molecule
D. The mass of the product

A. A precipitate

After the correct formula for a reactant in an equation has been written, the:

A. Subscripts are adjusted to balance the equation
B. Formula should not be changed
C. Same formula must appear as the product
D. Symbols in the formula must not appear on the product side of the equation

B. Formula should not be changed

What is the small whole number that appears in front of a formula in a chemical reaction?:

A. A subscript
B. A superscript
C. A ratio
D. A coefficient

D. A coefficient

To balance a chemical equation, it may be necessary to adjust the:

A. Coefficients
B. Subscripts
C. Formulas of the products
D. Number of products

A. Coefficients

According to the law of conservation of mass, the total mass of the reacting substances is:

A. Always more than the total mass of the proudcts
B. Always less than the total mass of the products
C. Sometimes more and sometimes less than the total mass of the products
D. Always equal to the total mass of products

D. Always equal to the total mass of the products

A chemical equation is balanced when the:

A. Coefficients of the reactants equal the coefficients of the products
B. Same number of each kind of atom appears in the reactants and in the products
C. Products and reactants are the same chemicals
D. Subscripts of the reactants equal the subscripts of the products

B. Same number of each kind of atom appears in the reactants and in the products

How would oxygen be represented in the formula equation for the reaction of methane and oxygen to yield carbon dioxide and water?

A. Oxygen
B. O
C. O2
D. 03

C. O2

Which of the following is a formula equation for the formation of carbon dioxide from carbon and oxygen?:

A. Carbon plus oxygen yields carbon dioxide
B. C + O2 --> CO2
C. CO2 --> C + O2
D. 2C + O --> CO2

B. C + O2 --> CO2

For the formula equation 2Mg + O2 --> 2MgO, the word equation would begin:

A. Manganese plus oxygen...
B. Molybdenum plus oxygen...
C. Magnesium plus oxygen...
D. Heat plus oxygen...

C. Magnesium plus oxygen

In an equation, the symbol for a substance in water solution is followed by:

A. (l)
B. (g)
C. (aq)
D. (s)

A. (l)

A chemical formula written over the arrow in a chemical equation signifies:

A. A byproduct
B. The formation of a gas
C. A catalyst for the reaction
D. An impurity

C. A catalyst for the reaction

Which coefficients correctly balance the formula equation NH4NO2(s)-->N2(g)+H2O9(l)?:

A. 1, 2, 2
B. 1, 1, 2
C. 2, 1, 1
D. 2, 2, 2

B. 1, 1, 2

After the first steps in writing an equation, the equation is balanced by:

A. Adjusting the subscripts to the formula(s)
B. Adjusting coefficients to the smallest whole-number ratio
C. Changing the products formed
D. Making the number of reactants equal to the number of products

B. Adjusting coefficients to the smallest whole-number ratio