Q: Which of the following is the correct formula to calculate the amount of required material in a reaction?

$$\dfrac{\text{Required}}{\text{Given}} \times \text{Given} = \text{Required}$$

Question 1

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

Accepted Answer

They show the relative number of moles of each reactant and product.

Question 2

Given the balanced equation $$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)}$$, how many moles of $$\mathrm{O_2$}$$ are required to completely react with 3 moles of $$\mathrm{CH_4$}$$?

Accepted Answer

6 moles

Question 3

In the reaction $$\mathrm{2\ C_5H_{18}(l) + 25\ O_2$(g) \rightarrow 16\ CO_2$(g) + 18\ H_2O(g)}$$, what is the mole ratio of $$\mathrm{O_2$} to$$ $$\mathrm{CO_2$}$$?

Accepted Answer

$$\dfrac{25}{16}$$

Question 4

Which of the following is the correct balanced equation for the combustion of methane?

Accepted Answer

$$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)}$$

Question 5

When balancing a chemical equation, which of the following must remain unchanged?

Accepted Answer

The subscripts within the chemical formulas

Question 6

A student is asked to balance the equation $$\mathrm{$$BaCl_2$$(aq) + Na_2SO_4(aq) \rightarrow $$BaSO_4$$(s) + NaCl(aq)}. $$What is the correct set of coefficients?

Accepted Answer

$$1, 1, 1, 2$$

Question 7

If 22.0 moles of $$\mathrm{C_5H_{18}}$$ are burned according to $$\mathrm{2\ C_5H_{18}(l) + 25\ O_2$(g) \rightarrow 16\ CO_2$(g) + 18\ H_2O(g)}$$, how many moles of $$\mathrm{CO_2$}$$ are produced?

Accepted Answer

176 moles

Question 8

Which statement about balancing chemical equations is correct?

Accepted Answer

The total number of atoms of each element must be equal on both sides.

Question 9

In the reaction $$\mathrm{6\ CO_2$(g) + 6\ H_2O(l) \rightarrow C_6H_{12}O_6$(s) + 6\ O_2$(g)}$$, what is the total number of oxygen atoms on the reactant side?

Accepted Answer

18

Question 10

A chemical reaction is represented as $$\mathrm{2\ Al(s) + 3\ Cl_2$(g) \rightarrow 2\ $$AlCl_3$$(s)}. If $$you start with 6 moles of $$\mathrm{Cl_2$}$$, how many moles of $$\mathrm{$$AlCl_3$$}$$ can be formed?

Accepted Answer

4 moles

Question 11

Which of the following best explains why chemical equations must be balanced?

Accepted Answer

To obey the law of conservation of mass.

Question 12

In the equation $$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)}$$, what is the ratio of moles of $$\mathrm{H_2O}$$ produced to moles of $$\mathrm{CH_4$}$$ consumed?

Accepted Answer

$$2:1$$

Question 13

A reaction is given as $$\mathrm{3\ Ba(NO_3$)_2(aq) + 2\ Na_3PO_4(aq) \rightarrow Ba_3$(PO_4$)_2(s) + 6\ $$NaNO_3$$(aq)}. $$How many moles of $$\mathrm{$$NaNO_3$$}$$ are produced when 1 mole of $$\mathrm{Ba_3$(PO_4$)_2} is $$formed?

Accepted Answer

6 moles

Question 14

Which of the following is NOT a correct step in balancing a chemical equation?

Accepted Answer

Change the subscripts within chemical formulas to balance atoms.

Question 15

If you have 10 moles of $$\mathrm{O_2$}$$, how many moles of $$\mathrm{H_2O}$$ can be produced according to $$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)}$$?

Accepted Answer

10 moles

Question 16

Which of the following best describes the physical state symbol (s) in a chemical equation?

Accepted Answer

It means the substance is a solid.

Question 17

In the reaction $$\mathrm{2\ $$KClO_3$$(s) \rightarrow 2\ KCl(s) + 3\ O_2$(g)}$$, how many moles of $$\mathrm{O_2$}$$ are produced from 4 moles of $$\mathrm{$$KClO_3$$}$$?

Accepted Answer

6 moles

Question 18

A balanced chemical equation is necessary for which of the following calculations?

Accepted Answer

Determining the mass of reactants needed for a reaction.

Question 19

Which of the following is the correct formula to calculate the amount of required material in a reaction?

Accepted Answer

$$\dfrac{	ext{Required}}{	ext{Given}} 	imes 	ext{Given} = 	ext{Required}$$

Chemical Reactions and Chemical Quantities: Equations and Stoichiometry

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