Q: How many molecules are present in 0.250 moles of $$\mathrm{CO_2$}$$?

$$1.51 \times 10$$^{23}$$ molecules

Q: How many hydrogen atoms are present in 0.205 moles of $$\mathrm{NH_3$}$$?

$$3.70 \times 10$$^{23}$$ atoms

Question 1

Which of the following observations is NOT typically evidence of a chemical change?

Accepted Answer

A change in state from solid to liquid with no new substance formed

Question 2

Which of the following best describes the law of conservation of mass as it applies to chemical reactions?

Accepted Answer

The total mass of the reactants equals the total mass of the products

Question 3

Balance the following equation: $$\mathrm{P_4$(s) + Br_2$(l) \rightarrow $$PBr_3$$(g)}$$

Accepted Answer

$$\mathrm{P_4$(s) + 6Br_2(l) \rightarrow 4PBr_3(g)}$$

Question 4

How many molecules are present in 0.250 moles of $$\mathrm{CO_2$}$$?

Accepted Answer

$$1.51 	imes 10$$^{23}$$ molecules

Question 5

What is the molar mass of potassium dichromate, $$\mathrm{K_2Cr_2O_7}$$?

Accepted Answer

$$294.2\ \mathrm{g/mol}$$

Question 6

A sample contains $$1.8 	imes 10$$^{24}$$ atoms of sulfur. What is the mass of sulfur in grams? (Molar mass of S = 32.07 g/mol)

Accepted Answer

$$95.9\ \mathrm{g}$$

Question 7

Which of the following is a decomposition reaction?

Accepted Answer

$$2\mathrm{$$KClO_3$$(s) \rightarrow 2KCl(s) + 3O_2(g)}$$

Question 8

How many moles of $$\mathrm{NaCl}$$ are in a 737 g box of table salt? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$12.6$$ moles

Question 9

Which of the following reactions is a combustion reaction?

Accepted Answer

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

Question 10

In the reaction $$\mathrm{4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)}$$, how many moles of Fe are needed to react with 12.0 moles of $$\mathrm{O_2$}$$?

Accepted Answer

$$16.0$$ moles

Question 11

Which of the following is the correct mole-to-mole conversion factor for the reaction $$\mathrm{2Fe(s) + 3S(s) \rightarrow Fe_2S_3(s)}$$?

Accepted Answer

$$\dfrac{1\ \mathrm{mol}\ Fe_2S_3}{2\ \mathrm{mol}\ Fe}$$

Question 12

A glass of water contains 250. g of water. How many moles of water are in the glass? (Molar mass of $$\mathrm{H_2O} = 18.02 g/$$mol)

Accepted Answer

$$13.9$$ moles

Question 13

Which of the following is an example of an exothermic reaction?

Accepted Answer

Combustion of propane in a grill

Question 14

Which reactant is oxidized in the reaction $$\mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)}$$?

Accepted Answer

$$\mathrm{Zn(s)}$$

Question 15

How many hydrogen atoms are present in 0.205 moles of $$\mathrm{NH_3$}$$?

Accepted Answer

$$3.70 	imes 10$$^{23}$$ atoms

Question 16

Given the reaction $$\mathrm{N_2$(g) + 3H_2(g) \rightarrow 2NH_3(g)}$$, how many grams of $$\mathrm{NH_3$}$$ can be produced from 2.50 g of $$\mathrm{N_2$}$$ and 3.00 g of $$\mathrm{H_2$}$$? (Molar masses: $$\mathrm{N_2$} = 28.02 g/$$mol, $$\mathrm{H_2$} = 2.016 g/$$mol, $$\mathrm{NH_3$} = 17.03 g/$$mol)

Accepted Answer

$$3.04 g$$

Question 17

Which of the following statements about limiting reactants is TRUE?

Accepted Answer

The limiting reactant determines the maximum amount of product that can form

Question 18

Which of the following is the correct interpretation of the coefficients in the balanced equation $$2\mathrm{Ag(s) + S(s) \rightarrow Ag_2S(s)}$$?

Accepted Answer

2 moles of Ag react with 1 mole of S to form 1 mole of $$\mathrm{Ag_2S}$$

Chapter 7 – Chemical Reactions and Quantities: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard