Q: How many atoms are present in 2.00 moles of sodium (Na)?

$$1.20 \times 10$$^{24}$$ atoms

Q: A 59.8 g sample of water contains how many molecules of water? (Molar mass $$H_2O = 18.02\ g/mol)$$

$$2.00 \times 10$$^{24}$$ molecules

Question 1

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

Accepted Answer

Dissolving salt in water

Question 2

What is the correct balanced equation for the reaction of aluminum with iron(III) oxide to produce iron and aluminum oxide?

Accepted Answer

$$2Al(s) + 3FeO(s) \rightarrow 3Fe(s) + Al_2O_3(s)$$

Question 3

How many atoms are present in 2.00 moles of sodium (Na)?

Accepted Answer

$$1.20 	imes 10$$^{24}$$ atoms

Question 4

What is the molar mass of potassium dichromate, $$K_2Cr_2O_7$$? (K = 39.10 g/mol, Cr = 52.00 g/mol, O = 16.00 g/mol)

Accepted Answer

$$294.20\ g/mol$$

Question 5

A sample contains 29.0 g of sodium chloride ($$NaCl). $$How many moles of $$NaCl$$ are present? (Molar mass $$NaCl = 58.44\ g/mol)$$

Accepted Answer

$$0.496$$ moles

Question 6

Which of the following best describes the law of conservation of mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products

Question 7

How many moles of oxygen atoms are in 1 mole of $$H_2SO_4$$?

Accepted Answer

4 moles

Question 8

Given the balanced equation: $$2Fe(s) + 3S(s) \rightarrow Fe_2S_3(s)$$, what is the mole ratio of Fe to $$Fe_2S_3$$?

Accepted Answer

$$2:1$$

Question 9

Which of the following statements about oxidation and reduction is TRUE?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons

Question 10

A 36.0 g sample of glucose ($$C_6H_{12}O_6$) is dissolved in water. How many moles of glucose are present? (Molar mass C_6H$$_{12}$$O_6 = 180.16$$\ g/mol$$)

Accepted Answer

$$0.200$$ moles

Question 11

Which of the following is the correct mole-to-mole factor for the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s) to $$convert moles of $$O_2 to $$moles of $$Fe_2O_3$$?

Accepted Answer

$$\frac{2\ moles\ Fe_2O_3}{3\ moles\ O_2$}$$

Question 12

If 5.0 moles of $$O_2$$ react according to $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$, how many moles of $$Fe_2O_3$$ are produced?

Accepted Answer

$$3.3$$ moles

Question 13

Which of the following best describes the role of Avogadro's number in chemistry?

Accepted Answer

It is the number of particles in one mole of a substance

Question 14

Which of the following reactions is an example of an oxidation-reduction (redox) reaction?

Accepted Answer

$$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$

Question 15

How many moles of hydrogen atoms are in 2 moles of $$C_2H_6$$?

Accepted Answer

12 moles

Question 16

A 59.8 g sample of water contains how many molecules of water? (Molar mass $$H_2O = 18.02\ g/mol)$$

Accepted Answer

$$2.00 	imes 10$$^{24}$$ molecules

Question 17

Which of the following is the correct set of coefficients to balance the equation: $$Fe_2O_3(s) + C(s) \rightarrow Fe(s) + CO_2$(g)$$?

Accepted Answer

2, 3, 4, 3

Question 18

Which of the following best describes reduction in a biological system?

Accepted Answer

Gain of electrons or hydrogen atoms

Question 19

If 0.50 moles of $$MgCl_2$$ react with excess $$Na_3PO_4$$ according to $$2Na_3PO_4(aq) + 3MgCl_2(aq) \rightarrow Mg_3$(PO_4$)_2(s) + 6NaCl(aq)$$, how many moles of $$Mg_3$$($$PO_4)_2$ will be formed?

Accepted Answer

$$0.17$$ moles

Chapter 7: Chemical Reactions and Quantities – Study Notes

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