Amount of Substances

Question 1

what is the equation linking moles, mass and Mr?

Answer 1

moles = mass/mr

Question 2

what is the equation for the number of particles?

Answer 2

number of particles = moles x 6.02x10(23)

Question 3

what is the equation for calculating moles when gas volume is given(RTP)?

Answer 3

moles=volume/ 24dm3(24000cm3)

Question 4

what is the equation for ideal gas?

Answer 4

pV=nRT

Question 5

what are the units for the pV= nRT equation?

Answer 5

p=pressure(Pa)
v=volume(m3)
n=moles
R=8.314
T=temperature(Kelvin’s)

Question 6

how do you go from kPa to Pa?

Answer 6

x1000

Question 7

how do you go from cm3 to m3?

Answer 7

x10-6

Question 8

how do you go from dm3 to m3?

Answer 8

divide by 1000

Question 9

what is the equation linking moles, concentration and volume?

Answer 9

concentration = moles/ volume

Question 10

how do you do from gdm-3 to moldm-3?

Answer 10

divide by mr

Question 11

what is the equation for atom economy?

Answer 11

mass of desired product/ mass of all products x100

Question 12

what is the equation for percentage yield?

Answer 12

actual amount of product/ theoretical amount of product x100

Question 13

why is it sustainable to have a high atom economy?

Answer 13

• less chemical waste is produced
• less money wasted
• chemistry is more sustainable

Question 14

how can we improve atom economy?

Answer 14

• reduce mr of unwanted products
• find another use of the unwanted products

Question 15

why do we heat until a constant mass in water of crystallisation?

Answer 15

to make sure all of the water is removed

Question 16

what is the mole?

Answer 16

unit for amount of substance

Question 17

what is empirical formula?

Answer 17

the simplest whole number ratio of atoms of each element present in a compound

Question 18

what is molecular formula?

Answer 18

the number and type of atoms of each element in a molecule