Question 1

While skeleton equations provide us with a lot of information about a chemical reaction, they are not perfect. What is a major limitation to skeleton equations?

Accepted Answer

They don't tell us how much of each substance is needed for the reaction, just what is present.

Answer

They indicate what conditions under which the reaction occurs (temperature, presence of a catalyst, etc.).

Answer

They tell us the physical state of each reactant and product in the reaction.

Answer

They tell us too much information about a reaction. We only need the minimum amount of information required to know what will happen.

Question 2

The physical law that states matter cannot be created or destroyed in a chemical reaction is referred to as the ______.

Accepted Answer

law of conservation of mass

Answer

law of conservation of energy

Answer

mandate of mass management

Answer

law of conservation of momentum

Question 3

According to the law of conservation of mass, what two things are conserved during a chemical reaction?

Accepted Answer

mass and atoms

Answer

mass and protons

Answer

density and atoms

Answer

volume and atoms

Question 4

Who is credited with the discovery of the law of conservation of mass?

Accepted Answer

Antoine Lavoisier

Answer

Ernest Rutherford

Answer

JJ Thomson

Answer

John Dalton

Question 5

In order to balance chemical equations, we put ______ to the ______ of chemical formulas and symbols in a chemical equation.

Accepted Answer

coefficients, left

Answer

coefficients, right

Answer

fractions, left

Answer

decimals, right

Question 6

What must you never change when balancing chemical equations?

Accepted Answer

the subscripts for the chemical formulas

Answer

the coefficients

Answer

the order of the reactants

Answer

the charges of the ions

Question 7

How many sodium atoms are present in the following compound? Type your answer in the space below.

4 Na₃PO₄

Accepted Answer

12

Question 8

How many phosphorus atoms are present in the following compound? Type your answer in the space below.

4 Na₃PO₄

Accepted Answer

4

Question 9

How many oxygen atoms are present in the following compound? Type your answer in the space below.

4 Na₃PO₄

Accepted Answer

16

Question 10

How many oxygen atoms are present in the following compound? Type your answer in the space below.

3 Be(ClO₄)₂

Accepted Answer

24

Question 11

How many chlorine atoms are present in the following compound? Type your answer in the space below.

3 Be(ClO₄)₂

Accepted Answer

6

Question 12

Which of the following chemical equations is unbalanced?

Accepted Answer

H₂ + O₂ $\ \ \longrightarrow\ \$ 2 H₂O

Answer

2 Al + 3 Cl₂ $\ \ \longrightarrow\ \$ 2 AlCl₃

Answer

N₂ + 3 H₂ $\ \ \longrightarrow\ \$ 2 NH₃

Answer

2 KClO₃ $\ \ \longrightarrow\ \$ 2 KCl + 3 O₂

Question 13

Which of the following chemical equations is unbalanced?

Accepted Answer

NaBr + CaF₂ $\ \ \longrightarrow\ \$ 2 NaF + CaBr₂

Answer

CH₄ + 2 O₂ $\ \ \longrightarrow\ \$ 2 H₂O + CO₂

Answer

2 Na + 2 H₂O $\ \ \longrightarrow\ \$ 2 NaOH + H₂

Answer

FeCl₃ + 3 NaOH $\ \ \longrightarrow\ \$ Fe(OH)₃ + 3 NaCl

Question 14

Which of the following chemical equations is unbalanced?

Accepted Answer

H₃PO₄ + 2 KOH $\ \ \longrightarrow\ \$ 3 K₃PO₄ + H₂O

Answer

CH₄ + 4 Cl₂ $\ \ \longrightarrow\ \$ CCl₄ + 4 HCl

Answer

2 Al + 3 H₂SO₄ $\ \ \longrightarrow\ \$ 3 H₂ + Al₂(SO₄)₃

Answer

4 Fe + 3 O₂ $\ \ \longrightarrow\ \$ 2 Fe₂O₃

Question 15