Question 1

Which of the following is NOT a sign that a chemical reaction has occurred?

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

According to the law of conservation of mass, which statement is true for a balanced chemical equation?

Accepted Answer

The total mass of reactants equals the total mass of products

Question 5

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

Accepted Answer

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

Question 6

When sodium oxide reacts with water, what is the balanced chemical equation?

Accepted Answer

$$Na_2O + H_2O \rightarrow 2NaOH$$

Question 7

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

Accepted Answer

They indicate the number of molecules or moles of each substance

Question 8

A student writes the equation $$H_2$$ + $$O_2$$ \rightarrow H_2O$$. What is wrong with this equation?

Accepted Answer

It is not balanced; there are not enough oxygen atoms on the product side

Question 9

Balance the following equation: $$Al + $$CuCl_2$$ \rightarrow $$AlCl_3$$ + Cu$$

Accepted Answer

$$2Al + 3CuCl_2 \rightarrow 2AlCl_3 + 3Cu$$

Question 10

Which of the following is a correct representation of the reaction when charcoal (carbon) burns in air?

Accepted Answer

$$C + O_2$ \rightarrow CO_2$

Question 11

Which of the following equations is balanced?

Accepted Answer

$$2Na + Cl_2$ \rightarrow 2NaCl$$

Question 12

What is the balanced equation for the reaction of magnesium chloride with bromine to form magnesium bromide and chlorine gas?

Accepted Answer

$$MgCl_2$$ + $$Br_2$$ \rightarrow $$MgBr_2$$ + $$Cl_2$$

Question 13

Which of the following is a correct balanced equation for the formation of water from hydrogen and oxygen?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 14

If $$C_7H_8O_2$$ combusts in oxygen to form $$CO_2$$ and $$H_2O$$, what is the balanced equation?

Accepted Answer

$$C_7H_8O_2 + 9O_2 \rightarrow 7CO_2 + 4H_2O$$

Question 15

Which of the following is a correct statement about diatomic elements?

Accepted Answer

They exist as molecules containing two atoms in their natural state

Question 16

What is the balanced equation for the reaction of sodium sulfate with calcium nitrate to produce sodium nitrate and calcium sulfate?

Accepted Answer

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

Question 17

Which of the following is a correct balanced equation for the reaction: $$KClO_3$$ \rightarrow KCl + $$O_2$$?

Accepted Answer

$$2KClO_3 \rightarrow 2KCl + 3O_2$$

Question 18

Which of the following is a correct balanced equation for the reaction: $$Fe + HCl \rightarrow $$FeCl_2$$ + H_2$?

Accepted Answer

$$Fe + 2HCl \rightarrow $$FeCl_2$$ + H_2$

Chemical Reactions and Balancing Chemical Equations: Study Notes

Study Guide - Practice Questions