Q: A sample contains 0.25 mol of $$Ca(NO_3$)_2. $$How many oxygen atoms are present in this sample?

$$0.25 \times 6 \times 6.02 \times 10$$^{23}$$

Q: A sample of $$CCl_4$$ contains 12.2 g. How many chlorine atoms are present in the sample? (Molar mass of $$CCl_4 = 153.8 g/$$mol)

$$\frac{12.2}{153.8} \times 4 \times 6.02 \times 10$$^{23}$$

Q: If 0.45 mol of $$BaSO_4 is $$present, how many sulfur atoms are in the sample?

$$0.45 \times 6.02 \times 10$$^{23}$$

Question 1

Which of the following is the correctly balanced chemical equation for the reaction between oxygen gas and nitrogen monoxide to form nitrogen dioxide?

Accepted Answer

$$O_2 + 2NO$$ \rightarrow 2NO_2$$

Question 2

In the reaction $$2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2$(g)$$, how many hydrogen atoms are present on the reactant side?

Accepted Answer

4

Question 3

Methanol ($$CH_3OH) $$combusts in oxygen to produce carbon dioxide and water. What is the balanced equation for this reaction?

Accepted Answer

$$2CH_3OH + 3O_2 \rightarrow 2CO_2 + 4H_2O$$

Question 4

A sample contains 0.25 mol of $$Ca(NO_3$)_2. $$How many oxygen atoms are present in this sample?

Accepted Answer

$$0.25 	imes 6 	imes 6.02 	imes 10$$^{23}$$

Question 5

What is the empirical formula of a compound that contains 40.92% C, 4.58% H, and 54.50% O by mass?

Accepted Answer

Question 6

A hydrocarbon has an empirical formula of $$CH_2$$ and a molecular weight of 56 amu. What is its molecular formula?

Accepted Answer

$$C_4H_8$$

Question 7

If 2.40 g of $$NaOH$$ reacts according to $$2NaOH(s) + CO_2$(g) \rightarrow Na_2CO_3(s) + H_2O(l)$$, how many grams of $$Na_2CO_3$$ can be produced?

Accepted Answer

1.27 g

Question 8

Which of the following is the correct molar mass of glucose ($$C_6H_{12}O_6$)?

Accepted Answer

180.0 g/mol

Question 9

A sample of $$CCl_4$$ contains 12.2 g. How many chlorine atoms are present in the sample? (Molar mass of $$CCl_4 = 153.8 g/$$mol)

Accepted Answer

$$\frac{12.2}{153.8} 	imes 4 	imes 6.02 	imes 10$$^{23}$$

Question 10

Which of the following samples contains the fewest sodium atoms?

Accepted Answer

45 g sodium fluoride

Question 11

What is the percent composition by mass of nitrogen in calcium nitrate ($$Ca(NO_3$)_2$$)? (Ca = 40.08, N = 14.01, O = 16.00)

Accepted Answer

17.1%

Question 12

A sample of methyl benzoate contains 3.75 g of carbon, 0.316 g of hydrogen, and 1.251 g of oxygen. What is the empirical formula?

Accepted Answer

$$C_8H_8O_2$$

Question 13

If 1.50 mol of Al and 3.00 mol of $$Cl_2$$ combine in the reaction $$2Al(s) + 3Cl_2(g) \rightarrow 2AlCl_3(s)$$, which reactant is limiting and how many moles of $$AlCl_3$$ are formed?

Accepted Answer

Al is limiting, 1.50 mol $$AlCl_3$$

Question 14

What is the percent yield if 2.7 g of titanium(V) chloride is produced from 6.00 g of titanium metal and excess chlorine gas? (Theoretical yield = 3.0 g)

Accepted Answer

90%

Question 15

Which of the following is the correct balanced equation for the decomposition of barium carbonate when heated?

Accepted Answer

$$BaCO_3(s$$) \rightarrow BaO(s) + $$CO_2(g$$)$$

Question 16

How many grams of $$O_2$$ are produced from the decomposition of 4.50 g of $$KClO_3$$ according to $$2KClO_3(s) \rightarrow 2KCl(s) + 3O_2(g)$$? (Molar mass $$KClO_3 = 122.55 g/$$mol)

Accepted Answer

0.59 g

Question 17

A sample of propane ($$C_3H_8) $$weighing 100 g is combusted. What mass of $$O_2 is $$consumed in the reaction?

Accepted Answer

363.8 g

Question 18

If 0.45 mol of $$BaSO_4 is $$present, how many sulfur atoms are in the sample?

Accepted Answer

$$0.45 	imes 6.02 	imes 10$$^{23}$$

Balancing Chemical Equations and Types of Chemical Reactions

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