amount of substance

Question 1

what is a mole?

Answer 1

amount of substance containing as many particles as there are C atoms in12.0g of carbon-12.

Question 2

define molar mass

Answer 2

mass of one mole of a substance
(gmol-1)

Question 3

state the ideal gas equation

Answer 3

pV=nRT

Question 4

what is Avogadro’s Constant?

Answer 4

the number of atoms in 12.0g of carbon-12
6.02 x10^23

Question 5

what is empirical formula?

Answer 5

simplest whole-number ratio of atoms of each element within a compound

Question 6

what is molecular formula?

Answer 6

the actual number of atoms of each element within a molecule

Question 7

what is the equation for the number of moles of a substance?

Answer 7

n=m/Mr
n= number of moles
m= mass
Mr= molecular mass

Question 8

what is RTP?

Answer 8

293K and 101kPa

Question 9

molar volume of any gas at RTP?

Answer 9

the volume of one mole of gas is 24.0dm3

Question 10

what is avogadro’s hypothesis?

Answer 10

equal volumes of gases at the same temp and pressure contain equal numbers of particles

Question 11

what is the equation for calculating percentage yield?

Answer 11

actual moles of products made/theoretical moles of product X 100

Question 12

what does percentage yield measure?

Answer 12

efficiency of a lab or industrial preparation

Question 13

what does atom economy measure?

Answer 13

percentage of useful products

Question 14

what is the equation for calculating number of particles?

Answer 14

number of particles = n x Na

Question 15

what is the equation for calculating molecular formula?

Answer 15

relative molecular mass/relative empirical formula mass X empirical formula

Question 16

what is molar volume?

Answer 16

• the volume of one mole of gas and is the same for all gases at the same temp and pressure
• at RTP one mole of any gas occupies 24.0 dm3

Question 17

what is the relationship between volume and temperature when moles and pressure are kept constant?

Answer 17

linear
- as volume increases, so does temp

Question 18

what is the relationship between pressure and temperature if moles and volume are kept constant?

Answer 18

linear
- as pressure increases, so does temp

Question 19

what is the relationship between pressure and volume if moles and temperature are kept constant?

Answer 19

• as pressure increases, volume decreases

Question 20

equation for calculating moles using conc and vol

Answer 20

n = cv

Question 21

what is concentration?

Answer 21

the concentration of a solution is the amount of solute (in moles) dissolved per 1 dm3 (1000cm3) of solution

Question 22

what are the assumptions made about an ideal gas?

Answer 22

• random motion
• elastic conditions
• negligible size
• no intermolecular forces

Question 23

what is stoichiometry?

Answer 23

the balancing numbers giving the ratio of the amount, in moles, of each substance in a balanced equation.

Question 24

why is the theoretical yield so hard to achieve?

Answer 24

• reaction is incomplete
• competing side reactions give different products
• loss of product in handling and purification
• reversible reaction

Question 25

what is the limiting reagent?

Answer 25

the reactant that is not in excess

Question 26

what are the benefits of a high atom economy?

Answer 26

• produce a larger proportion of desired products and few waste products
• important for sustainability, the best use of natural resources