Question 1

Which of the following is NOT a sign of a chemical reaction?

Accepted Answer

Melting of ice

Question 2

What does the symbol $$(aq)$$ represent in a chemical equation?

Accepted Answer

Aqueous, meaning dissolved in water

Question 3

Which of the following elements is DIATOMIC in its natural state?

Accepted Answer

Oxygen ($$O_2)$$

Question 4

When charcoal (carbon) burns in air, it reacts with oxygen to form carbon dioxide. Which balanced equation correctly represents this reaction?

Accepted Answer

$$C(s) + O_2$(g) \rightarrow CO_2$(g)$$

Question 5

According to the law of conservation of mass, which statement is TRUE for a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products

Question 6

Balance the following equation: $$2Al(s) + 3CuCl_2(aq) \rightarrow 2AlCl_3(aq) + 3Cu(s). $$What is the coefficient for $$CuCl_2$$?

Accepted Answer

3

Question 7

Which of the following best describes why equations must be balanced?

Accepted Answer

To ensure the number of atoms of each element is the same on both sides

Question 8

What is the balanced equation for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2(g) + O_2$(g) \rightarrow 2H_2O(l)$$

Question 9

Which of the following is a correct representation of a chemical reaction using symbols?

Accepted Answer

$$Na_2SO_4(aq) + Ca(NO_3$)_2(aq) \rightarrow 2NaNO_3(aq) + $$CaSO_4$$(s)$$

Question 10

A student observes bubbling and a temperature increase when mixing two solutions. What is the best explanation?

Accepted Answer

A chemical reaction is occurring, producing a gas and releasing energy

Question 11

Balance the following equation: $$C_3H_8 + O_2$ \rightarrow CO_2$ + H_2O. $$What are the correct coefficients?

Accepted Answer

$$1, 5, 3, 4$$

Question 12

Which of the following is a correct balanced equation for the reaction of sodium oxide with water to form sodium hydroxide?

Accepted Answer

$$Na_2O + H_2O \rightarrow 2NaOH$$

Question 13

If a chemical equation is not balanced, which law is being violated?

Accepted Answer

Law of Conservation of Mass

Question 14

Balance the following equation: $$MgBr_2$$ + $$Cl_2$$ \rightarrow $$MgCl_2$$ + $$Br_2. $$What is the coefficient for $$Cl_2$$?

Accepted Answer

1

Question 15

Which of the following is a real-world example of a chemical reaction?

Accepted Answer

Iron rusting when exposed to air

Question 16

Balance the following equation: $$C_7H_{16} + O_2$ \rightarrow CO_2$ + H_2O. $$What is the coefficient for $$O_2$$?

Accepted Answer

11

Question 17

Which of the following best describes the role of coefficients in a chemical equation?

Accepted Answer

They indicate the number of molecules or moles of each substance

Question 18

Balance the following equation: $$Sn + Cl_2$ \rightarrow $$SnCl_2$$. What is the coefficient for Sn$?

Accepted Answer

1

Question 19

Which of the following is a correct balanced equation for the combustion of butane ($$C_4H_{10}$$)?

Accepted Answer

$$2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O$$

Chemical Reactions and Balancing Chemical Equations

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