Text A Chemistry 3.4 The Mole

Question 1

What is Avogadro’s number?

Answer 1

6.022 141 99 x 10²³

Avogadro’s number represents the number of elementary entities in one mole of a substance.

Question 2

Who is Avogadro’s law named after?

Answer 2

Amedeo Avogadro

Amedeo Avogadro was an Italian chemist who proposed the law in 1811.

Question 3

What does Avogadro’s law state?

Answer 3

Equal volumes of gases, at equal temperatures and pressures, contain the same number of molecules

This law is fundamental in understanding gas behavior and stoichiometry.

Question 4

What is the definition of a mole?

Answer 4

The amount of substance that contains as many elementary entities as exactly 12 g of carbon-12

The mole is a fundamental unit in chemistry for quantifying substance amounts.

Question 5

How many elementary entities are in one mole of a substance?

Answer 5

6.022 141 99 x 10²3

This value is known as Avogadro’s number.

Question 6

What is the symbol for the mole?

Answer 6

mol

Question 7

How many significant digits are in the most precise determination of Avogadro’s number?

Answer 7

Nine

Question 8

Fill in the blank: One mole of carbon contains _______ carbon atoms.

Answer 8

6.02 x 10²3

Question 9

Fill in the blank: One mole of carbon dioxide, CO2, contains _______ molecules.

Answer 9

6.02 x 10²3

Question 10

Fill in the blank: One mole of sodium chloride, NaCl, contains _______ formula units.

Answer 10

6.02 x 10²3

Question 11

How long would it take to go broke if you built three Calgary Towers each second?

Answer 11

Nearly 2 billion years

Question 12

How much did it cost to build the Calgary Tower?

Answer 12

$3.5 million

Question 13

What is a counting unit in everyday life?

Answer 13

Examples include dozen, pairs, six-pack

These units help simplify counting large quantities.

Question 14

How does Avogadro’s number relate to visualizing large quantities?

Answer 14

It can be related to everyday objects, like pennies covering the surface of Alberta

This helps to comprehend the vast size of Avogadro’s number.

Question 15

What is the significance of the mole in chemistry?

Answer 15

It allows chemists to group large numbers of particles into manageable amounts.

Question 16

True or False: Avogadro’s law was recognized during Avogadro’s lifetime.

Answer 16

False

Question 17

What is the numerical value of a mole in terms of particles?

Answer 17

6.02 x 10^23 particles

This number is known as Avogadro’s number.

Question 18

Why is it important to measure amounts of substances in moles?

Answer 18

It provides a convenient way to relate mass and amount of a substance.

Question 19

How can chemists determine the mass of one mole of a substance?

Answer 19

By using the relative masses of elements.

Question 20

True or False: The concept of a mole is useful in practical applications.

Answer 20

True

Question 21

Fill in the blank: A mole is defined as _______ particles.

Answer 21

6.02 x 10^23

Question 22

What do chemists use to calculate the mass of one mole of a substance?

Answer 22

Relative masses of elements.

Question 23

What is the atomic molar mass (M) of an element?

Answer 23

A weighted average of the mass of 1 mol of all naturally occurring isotopes of the element

The atomic molar mass is listed on the periodic table for each element.

Question 24

What is the atomic molar mass of iron?

Answer 24

55.85 g/mol

This means the mass of 1 mol of iron is 55.85 g.

Question 25

What is the atomic molar mass of sodium?

Answer 25

22.99 g/mol ## Footnote This means the mass of 1 mol of sodium is 22.99 g.

Question 26

How many atoms are in 1 mol of a substance?

Answer 26

6.02 × 10^23 atoms ## Footnote This is known as Avogadro's number.

Question 27

What does the element nitrogen exist as?

Answer 27

A molecule composed of two nitrogen atoms, N2 ## Footnote Therefore, 1 mol of nitrogen molecules contains 2 mol of nitrogen atoms.

Question 28

What is the molar mass of nitrogen molecules?

Answer 28

28.02 g/mol ## Footnote This is calculated as 2 x 14.01 g/mol.

Question 29

What is the formula used to determine the molar mass of a compound?

Answer 29

The chemical formula of the compound ## Footnote For example, CO2 indicates one carbon atom and two oxygen atoms.

Question 30

Fill in the blank: The molar mass (M) is used to refer to the mass of 1 mol of any _______.

Answer 30

pure substance

Question 31

What units are used for molar mass?

Answer 31

g/mol

Question 32

What is the factor label method used for?

Answer 32

It is used to convert between the amount of a sample expressed in moles and the mass of the sample expressed in grams. ## Footnote The method utilizes conversion factors to change units without affecting the value.

Question 33

What is the conversion factor to change moles to grams?

Answer 33

The molar mass of the substance. ## Footnote The molar mass is expressed in grams per mole (g/mol).

Question 34

What is the molar mass of helium?

Answer 34

4.00 g/mol. ## Footnote This means that 4.00 g of helium is equivalent to 1 mol of helium.

Question 35

How do you determine the mass of 2 mol of helium?

Answer 35

Multiply 2 mol by the molar mass of helium (4.00 g/mol). ## Footnote The calculation is: mass of helium = 2 mol He x (4.00 g He / 1 mol He).

Question 36

What is the formula to convert mass to amount in moles?

Answer 36

n = m / M ## Footnote Where n is the amount in moles, m is the mass in grams, and M is the molar mass in g/mol.

Question 37

Fill in the blank: To convert from mass to amount, you use the equation n = m / _______.

Answer 37

M ## Footnote M represents the molar mass in g/mol.

Question 38

True or False: The factor label method can only be used to convert from grams to moles.

Answer 38

False. ## Footnote The method can be used to convert in both directions: moles to grams and grams to moles.

Question 39

What does 'm' stand for in the equation n = m / M?

Answer 39

Mass (g). ## Footnote 'm' is the mass of the substance in grams.

Question 40

In the conversion factor, what does 'M' represent?

Answer 40

Molar mass (g/mol). ## Footnote 'M' is the mass of one mole of the substance expressed in grams.

Question 41

What is the mass of 2 mol of H2?

Answer 41

The mass is shown in Table 3.5. ## Footnote Specific value to be referenced from Table 3.5.

Question 42

What is the mass of 1 mol of O2?

Answer 42

The mass is shown in Table 3.5. ## Footnote Specific value to be referenced from Table 3.5.

Question 43

What is the mass of 2 mol of H2O?

Answer 43

The mass is shown in Table 3.5. ## Footnote Specific value to be referenced from Table 3.5.

Question 44

Write the balanced chemical equation for the formation of sodium chloride.

Answer 44

Na + Cl → NaCl ## Footnote This represents the reaction between sodium and chlorine.

Question 45

What is the law that states the total mass of reactants equals the total mass of products?

Answer 45

Law of Conservation of Mass. ## Footnote This law applies to balanced chemical equations.

Question 46

How can coefficients in a balanced chemical equation be interpreted?

Answer 46

They can represent: * Number of particles (molecules or formula units) * Amount in moles of each substance involved ## Footnote This dual interpretation is crucial for stoichiometric calculations.

Question 47

What happens when you multiply all coefficients in a balanced chemical equation by two?

Answer 47

The equation remains balanced. ## Footnote This demonstrates the scalability of chemical equations.

Question 48

Fill in the blank: 2H2(g) + O2(g) → 2H2O ______.

Answer 48

2 molecules ## Footnote This refers to the number of molecules involved in the reaction.

Question 49

True or False: The total mass of the product is always equal to the total mass of the reactants in a balanced chemical equation.

Answer 49

True. ## Footnote This is a fundamental principle of chemical reactions.

Question 50

What does Table 3.5 illustrate about chemical equations?

Answer 50

It shows the relationship between molecules, moles, and mass. ## Footnote This table exemplifies the law of conservation of mass in chemical reactions.

Question 51

How many molecules are in 2 mol of a substance?

Answer 51

2 × 6.02 × 10^23 molecules. ## Footnote This is based on Avogadro's number.

Question 52

What is the total mass of the reactants in the example provided?

Answer 52

36.04 g. ## Footnote This refers to the sum of the masses of H2 and O2 in the reaction.

Question 53

What is the total mass of the products in the example provided?

Answer 53

36.04 g. ## Footnote This confirms the law of conservation of mass in the reaction.