Q: Which of the following is the correct mole-mole factor between $$O_2$$ and $$Fe_2O_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$?

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

Q: How many molecules are present in 0.250 moles of $$CO_2$$?

$$1.51 \times 10$$^{23}$$ molecules$$\ (0.250 \times 6.02 \times $$10^{23}$$)$$

Q: How many atoms of oxygen are in $$0.200$$ mole of aspirin, $$C_9H_8O_4$$?

$$4.82 \times 10$$^{23}$$ atoms$$\ (0.200 \text{ mol } \times 4 \text{ mol O}/1 \text{ mol aspirin} \times 6.02 \times $$10^{23}$$)$$

Q: Which of the following reactions is an example of a combustion reaction?

$$C_2H_6(g) + 7O_2(g) \rightarrow 4CO_2(g) + 6H_2O(g) + \text{energy}$$

Question 1

Which of the following observations is NOT evidence of a chemical reaction?

Accepted Answer

Melting of ice

Question 2

What is the balanced chemical equation for the reaction of solid iron(III) oxide with hydrogen gas to produce solid iron and water?

Accepted Answer

$$Fe_2O_3(s) + 4H_2(g) \rightarrow 3Fe(s) + 4H_2O(l)$$

Question 3

Which type of chemical reaction is represented by the following equation? $$2KClO_3(s) \rightarrow 2KCl(s) + 3O_2(g)$$

Accepted Answer

Decomposition

Question 4

In the reaction $$2AgNO_3(aq) + Na_2SO_4(aq) \rightarrow Ag_2SO_4(s) + 2NaNO_3(aq)$$, what type of reaction is this?

Accepted Answer

Double replacement

Question 5

Which of the following is the correct mole-mole factor between $$O_2$$ and $$Fe_2O_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$?

Accepted Answer

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

Question 6

How many molecules are present in 0.250 moles of $$CO_2$$?

Accepted Answer

$$1.51 	imes 10$$^{23}$$ molecules$$\ (0.250 	imes 6.02 	imes $$10^{23}$$)$$

Question 7

What is the molar mass of $$C_2H_6O ($$ethanol)?

Accepted Answer

$$46.08\ g/mol$$

Question 8

A sample contains $$1.8 	imes 10$$^{24}$$ atoms of sulfur. How many moles of sulfur are present?

Accepted Answer

$$3.0$$ moles

Question 9

How many atoms of oxygen are in $$0.200$$ mole of aspirin, $$C_9H_8O_4$$?

Accepted Answer

$$4.82 	imes 10$$^{23}$$ atoms$$\ (0.200 	ext{ mol } 	imes 4 	ext{ mol O}/1 	ext{ mol aspirin} 	imes 6.02 	imes $$10^{23}$$)$$

Question 10

What is the limiting reactant when 10.0 moles of CO and 5.00 moles of $$H_2$$ react to form methanol ($$CH_3OH) $$according to $$CO(g) + 2H_2(g) \rightarrow CH_3OH(g)$$?

Accepted Answer

$$H_2$$

Question 11

Calculate the mass of $$NH_3$$ that can be formed when $$2.50$$ grams of $$N_2$$ reacts with $$2.00$$ grams of $$H_2$$ according to $$N_2(g) + 3H_2(g$$) \rightarrow 2NH_3(g)$$. (Molar masses: N_2$ = 28.02\ g/mol$$, $$H_2 = 2.02$$\ g/mol$$, NH_3$ = 17.04\ g/mol)$$

Accepted Answer

$$3.04\ g$$

Question 12

Which of the following is true about oxidation in a redox reaction?

Accepted Answer

It always involves a loss of electrons

Question 13

What is the percent yield if the actual yield of $$LiHCO_3 is$$ $$72.8$$ grams and the theoretical yield is $$142$$ grams?

Accepted Answer

$$51.3\%$$

Question 14

How much heat (in kJ) is released when nitrogen and hydrogen react to form $$50.0$$ grams of ammonia ($$NH_3) $$according to $$N_2(g) + 3H_2(g$$) \rightarrow 2NH_3(g)$$, $$\Delta H = -92.2\ kJ$$? (Molar mass NH_3$ = 17.03\ g/mol)$$

Accepted Answer

$$-135\ kJ$$

Question 15

Which of the following reactions is an example of a combustion reaction?

Accepted Answer

$$C_2H_6(g) + 7O_2(g) ightarrow 4CO_2(g) + 6H_2O(g) + 	ext{energy}$$

Question 16

Which statement best describes the law of conservation of mass?

Accepted Answer

The mass of the products is equal to the mass of the reactants

Question 17

What is the correct sequence of steps to convert grams of substance A to grams of substance B in a chemical reaction?

Accepted Answer

Grams A $$\rightarrow$$ moles A $$\rightarrow$$ moles B $$\rightarrow$$ grams B

Question 18

Which of the following is the correct molar mass for $$NaCl$$?

Accepted Answer

$$58.44\ g/mol$$

Question 19

In a single replacement reaction, which of the following is true?

Accepted Answer

One element replaces another in a compound

Chapter 7: Chemical Reactions and Quantities – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard