Moles

Question 1

Definition of Relative atomic mass (Ar)

Answer 1

average mass of the naturally occurring isotopes of the element relative to the mass of 1/12 of an atom of carbon-12

Question 2

Definition of relative molecular mass (Mr)

Answer 2

mass of a molecule of the compound relative to 1/12 of an atom of carbon-12

Question 3

Why are relative atomic masses “on average”?

Answer 3

weighted average of the naturally occurring isotopes of the element.

Question 4

Definition of relative formula mass

Answer 4

When compound contains ions, it is the mass of the formula unit relative to the mass of 1/12 of an atom of carbon-12

Question 5

How to find the number of molecules in a molecule?

Answer 5

mol x avagadro’s number

Question 6

How to find mol of specific atoms in a molecule?

Answer 6

mol x how many of that atom

Question 7

how to find number of specific atoms in a molecule?

Answer 7

number of molecules x however many of that atom.

mol of atoms x avagadro’s number

Question 8

How to find percentage composition of a compound?

Answer 8

Find Mr
Divide amount of specific atom by the Mr.
x by 100.

Question 9

Definition of empirical formula

Answer 9

the simplest whole number ratio of the elements present in a compound

Question 10

definition of molecular formula

Answer 10

the actual number of atoms of each element present in a molecule of the compound

Question 11

How to balance equations?

Answer 11

metals
non-metals
carbon
hydrogen
oxygen

Question 12

What is the relationship between atom economy and the amount of waste?

Answer 12

Inverse relationship – lower atom economy, more waste.

Question 13

What are the assumptions of an ideal gas?

Answer 13

consists of particles in constant, random motion.
Particles have no volume.
No force exists between particles (except when they collide)
All collisions between particles and between particles and the wall of the container are perfectly elastic (no change in total kinetic energy of colliding particles)

Question 14

When do gases deviate most from ideal behaviour?

Answer 14

at high pressure and low temperature

Question 15

What is avagadro’s law?

Answer 15

equal volumes of ideal gases measured at the same temperature and pressure contain the same number of molecules

Question 16

What is 0°C in Kelvin?

Answer 16

273.15K

Question 17

What is 0K in °C?

Answer 17

-273.15°C

Question 18

What is the relationship between pressure and volume? (Boyle’s law)

Answer 18

volume of a fixed mass of an ideal gas is inversely proportional to its pressure at constant temp.

Question 19

Draw graph of PV

Answer 19

|
|
|
<_______________

(curve not touching sides)

Question 20

Draw graph of P 1/V

Answer 20

(Diagonal from origin)

Question 21

Draw graph of PV vs P

Answer 21

(horizontal from middle of PV)

Question 22

What is the relationship between volume and temperature? (Charles’ Law)

Answer 22

volume of fixed mass of ideal gas directly proportional to temp in Kelvin.

Question 23

Draw graph of V vs T (in °C and K)

Answer 23

(K diagonal at origin)
(°C diagonal from -273.15°C)

Question 24

What is the relationship between Pressure and temperature (Gay-Lussac’s Law)

Answer 24

fixed mass of ideal gas at constant volume, pressure is directly proportional to its absolute temp

Question 25

What are the units of PV=nRT

Answer 25

P: Nm^-2 or Pa
V: m^3
T: K

Question 26

1m^3 = ____dm^3

Answer 26

1000dm^3

Question 27

1m^3 = _____cm^3

Answer 27

1000000cm^3