Question 1

Which of the following best describes the Law of Conservation of Matter as it applies to chemical reactions?

Accepted Answer

The total number of atoms of each element must be the same on both sides of a balanced chemical equation.

Question 2

Given the unbalanced equation $$\mathrm{C_3H_8} + \mathrm{O_2$} \rightarrow \mathrm{CO_2$} + \mathrm{H_2O}$$, what are the correct coefficients to balance the equation?

Accepted Answer

$$1, 5, 3, 4$$

Question 3

Which of the following is a double replacement reaction?

Accepted Answer

$$\mathrm{$$AgNO_3$$} + \mathrm{NaCl} \rightarrow \mathrm{AgCl} + \mathrm{$$NaNO_3$$}$$

Question 4

A student is asked to balance the equation $$\mathrm{Al} + \mathrm{O_2$} \rightarrow \mathrm{Al_2O_3}. $$What is the correct set of coefficients?

Accepted Answer

$$4, 3, 2$$

Question 5

Which statement about subscripts and coefficients in chemical equations is correct?

Accepted Answer

Coefficients are placed in front of compounds to balance equations.

Question 6

In the reaction $$\mathrm{2KClO_3} \rightarrow 2KCl + 3O_2$$, how many moles of oxygen gas are produced from 4 moles of potassium chlorate?

Accepted Answer

6 moles

Question 7

Which of the following reactions is a combustion reaction?

Accepted Answer

$$\mathrm{C_2H_6} + 3.5O_2 \rightarrow 2CO_2 + 3H_2O$$

Question 8

A student mixes 2.00 moles of hydrogen gas with excess nitrogen gas according to the reaction $$\mathrm{N_2$} + 3H_2 \rightarrow 2NH_3. $$How many moles of ammonia are produced?

Accepted Answer

1.33 moles

Question 9

Which of the following best describes a single replacement reaction?

Accepted Answer

One element replaces another in a compound.

Question 10

In the balanced equation $$\mathrm{2Al} + 3S \rightarrow Al_2S_3$$, how many moles of sulfur are required to react with 4 moles of aluminum?

Accepted Answer

6 moles

Question 11

A redox reaction involves:

Accepted Answer

The transfer of electrons between species.

Question 12

If 0.75 moles of $$\mathrm{$$AlCl_3$$}$$ are produced in the reaction $$Al + 3Cl_2 \rightarrow 2AlCl_3$$, how many grams of $$\mathrm{$$AlCl_3$$} is $$this? (Molar mass of $$\mathrm{$$AlCl_3$$} is 133.34 g/$$mol)

Accepted Answer

$$56.7 g$$

Question 13

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

Accepted Answer

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

Question 14

In the reaction $$\mathrm{Zn} + 2HCl \rightarrow $$ZnCl_2$$ + H_2$, what type of reaction is this?

Accepted Answer

Single replacement

Question 15

Which of the following is true about balancing chemical equations?

Accepted Answer

You should only change the coefficients to balance the equation.

Question 16

A student wants to produce 6.0 moles of $$\mathrm{CO_2$}$$ from the combustion of propane ($$\mathrm{C_3H_8}). $$How many moles of propane are required? ($$\mathrm{C_3H_8} + 5O_2 \rightarrow 3CO_2 + 4H_2O)$$

Accepted Answer

2.0 moles

Question 17

Which of the following is the correct oxidation number for oxygen in $$\mathrm{H_2SO_4}$$?

Accepted Answer

$$-2$$

Question 18

In the reaction $$\mathrm{2AgNO_3} + \mathrm{Cu} \rightarrow 2Ag + Cu(NO_3$)_2$$, what is the mole ratio of $$\mathrm{$$AgNO_3$$} to$$ $$\mathrm{Ag}$$?

Accepted Answer

$$2:2$$

Question 19

A student starts with 5.0 grams of hydrogen gas ($$\mathrm{H_2$}) $$and reacts it with excess oxygen to produce water. How many moles of water are produced? ($$\mathrm{H_2$} + \frac{1}{2}O_2$ \rightarrow H_2O$$; molar mass of $$\mathrm{H_2$} is 2.02 g/$$mol)

Accepted Answer

2.5 moles

Stoichiometry and Balancing Chemical Equations – Study Notes

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