Q: How many oxygen atoms are present in $$0.150$$ mole of aspirin ($$\mathrm{C_9H_8O_4}$$)?

$$3.61 \times 10$$^{23}$$ atoms

Q: If $$2.0$$ moles of $$\mathrm{Al}$$ are present, how many atoms of $$\mathrm{Al}$$ are there? ($$1\ \mathrm{mol} = 6.02 \times 10$$^{23}$$ atoms)

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

Question 1

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

Accepted Answer

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

Question 2

A sample of water has a mass of 59.8 grams. How many moles of water are in the sample? (Molar mass of $$\mathrm{H_2O} is$$ $$18.02\ \mathrm{g/mol})$$

Accepted Answer

$$3.32\ \mathrm{mol}$$

Question 3

Which of the following reactions is a decomposition reaction?

Accepted Answer

$$2\mathrm{H_2O_2} \rightarrow 2\mathrm{H_2O} + \mathrm{O_2$}$$

Question 4

How many oxygen atoms are present in $$0.150$$ mole of aspirin ($$\mathrm{C_9H_8O_4}$$)?

Accepted Answer

$$3.61 	imes 10$$^{23}$$ atoms

Question 5

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

Accepted Answer

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

Question 6

A reaction has a $$\Delta H = -92.2\ \mathrm{kJ}. $$Which statement is true about this reaction?

Accepted Answer

The reaction is exothermic and releases heat.

Question 7

If $$2.0$$ moles of $$\mathrm{Al}$$ are present, how many atoms of $$\mathrm{Al}$$ are there? ($$1\ \mathrm{mol} = 6.02 	imes 10$$^{23}$$ atoms)

Accepted Answer

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

Question 8

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

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

Question 9

A box of table salt contains $$737\ \mathrm{g} of$$ $$\mathrm{NaCl}. $$How many moles of $$\mathrm{NaCl}$$ are present? (Molar mass of $$\mathrm{NaCl} is$$ $$58.44\ \mathrm{g/mol})$$

Accepted Answer

$$12.6\ \mathrm{mol}$$

Question 10

Which of the following is a double replacement reaction?

Accepted Answer

$$\mathrm{Na_2SO_4} + \mathrm{$$BaCl_2$$} \rightarrow \mathrm{$$BaSO_4$$} + 2\mathrm{NaCl}$$

Question 11

In a reaction, $$3.00$$ moles of $$\mathrm{CO}$$ and $$5.00$$ moles of $$\mathrm{H_2$}$$ are mixed. If the reaction is $$\mathrm{CO} + 2\mathrm{H_2$} \rightarrow \mathrm{CH_3OH}$$, what is the limiting reactant and how many moles of $$\mathrm{CH_3OH}$$ can be produced?

Accepted Answer

$$\mathrm{H_2$} is $$limiting; $$2.50$$ moles of $$\mathrm{CH_3OH}$$

Question 12

A reaction has a theoretical yield of $$100\ \mathrm{g}$$, but only $$72\ \mathrm{g} of $$product is actually obtained. What is the percent yield?

Accepted Answer

$$72\%$$

Question 13

Which of the following is a real-life example of an exothermic reaction?

Accepted Answer

A candle burning in a dark room

Question 14

How many grams of $$\mathrm{CO_2$}$$ are produced from $$32.0\ \mathrm{g} of$$ $$\mathrm{CH_4$} in $$the reaction $$\mathrm{CH_4$} + 2\mathrm{O_2$} \rightarrow \mathrm{CO_2$} + 2\mathrm{H_2O}$$? (Molar mass: $$\mathrm{CH_4$} = 16.04\ \mathrm{g/mol}$$, $$\mathrm{CO_2$} = 44.01\ \mathrm{g/mol})$$

Accepted Answer

$$87.8\ \mathrm{g}$$

Question 15

Which of the following best describes a limiting reactant in a chemical reaction?

Accepted Answer

The reactant that is used up first and limits the amount of product formed.

Question 16

Which of the following is the correct molar mass for lithium carbonate ($$\mathrm{Li_2CO_3}$$)? (Atomic masses: $$\mathrm{Li} = 6.94$$, $$\mathrm{C} = 12.01$$, $$\mathrm{O} = 16.00)$$

Accepted Answer

$$73.89\ \mathrm{g/mol}$$

Question 17

Which of the following is a single replacement reaction?

Accepted Answer

$$\mathrm{Zn} + 2\mathrm{HCl} \rightarrow \mathrm{$$ZnCl_2$$} + \mathrm{H_2$}$$

Question 18

Which of the following statements about Avogadro’s number is correct?

Accepted Answer

Avogadro’s number is $$6.02 	imes 10$$^{23}$$ and represents the number of atoms, molecules, or ions in one mole of a substance.

Question 19

A patient is exposed to carbon monoxide ($$\mathrm{CO}) $$due to incomplete combustion in a poorly ventilated room. What is the primary health risk associated with $$\mathrm{CO}$$ exposure?

Accepted Answer

CO binds to hemoglobin, reducing oxygen delivery to cells.

Chemical Quantities and Reactions: GOB Chemistry Chapter 7 Study Notes

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