3.1.2 Amount of a Substance

Question 1

Define Relative atomic Mass (Ar)

Answer 1

The average mass of an atom of an element relative to 1/12th of a carbon atom

Question 2

Define Relative Molecular Mass (Mr)

Answer 2

The average mass of a molecule relative to 1/12th of a carbon atom

Question 3

What is Avogadro’s constant (as a number)?

Answer 3

6.022 × 10^23

Question 4

What does Avogadro’s constant represent?

Answer 4

The number of particles in a mole

Question 5

What is formula for concentration?

Answer 5

Concentration= Moles/Volume

Question 6

What is the Ideal gas equation?

Answer 6

pV=nRT

pressure (Pa) × Volume (m^3) = number of moles × gas constant × temperature (K)

Question 7

How to calculate Kelvins from Celsius

Answer 7

Celsius + 273 = Kelvins

Question 8

What is the empirical formula?

Answer 8

The simplest whole number ratio of atoms of each element in each compound

Question 9

What is the molecular formula?

Answer 9

The actual number of atoms of each element in a compound

Question 10

How to find out the molecular formula from the empirical formula?

Answer 10

Molecular formula = n × Empirical formula

Question 11

How to calculate n in formula to find out molecular formula?

Answer 11

Molar ratio of Molecular mass/ Molar ratio of Empirical mass

Question 12

What is the difference between a Full equation and an Ionic equation?

Answer 12

Full equation show everything meanwhile ionic equations only show the ions involved in the reaction (leaving out spectator ions)

Question 13

What is formula for percentage economy?

Answer 13

Percentage economy = Mr of desired product/ Mr of all reactants × 100

Question 14

What are Economic advantages for society and industry of developing chemical processes with high atom economy?

Answer 14

• Reduced Waste disposal Costs
• Lower Raw Material Costs

Question 15

What are Ethical advantages for society and industry of developing chemical processes with high atom economy?

Answer 15

• Conserves finite resources
• Less Toxic by-products protects human and animal life

Question 16

What are Environmental advantages for society and industry of developing chemical processes with high atom economy?

Answer 16

• Less waste and less harmful by-products means less pollution

Question 17

What is the equation for percentage yield?

Answer 17

Actual Yield/Theoretical Yield

Question 18

What is the used of Balanced equations?

Answer 18

They can be used to calculate masses and gas volumes