1.4/1.5 The mole & ideal gas

Question 1

relative atomic mass

Answer 1

Relative atomic mass, A, is the weighted average mass of one atom of an element relative to the 1/12 the mass of an atom of carbon-12.

Question 2

molar mass

Answer 2

The mass of a mole of a substance (g/mol)

Question 3

Percentage Yield

Answer 3

The experimental yield as a percentage of the maximum theoretical yield (expt/theo x 100)

Question 4

empirical formula

Answer 4

formula obtained by experiment, showing the simplest whole number ratio of atoms of each elements in a particle of a substance

Question 5

molecular formula

Answer 5

the actual number of atoms of elements in a compound

Question 6

concentration

Answer 6

amount of solutes per unit of volume of solutions

Question 7

room temperature and pressure

Answer 7

One mol of any gas occupies 24000 cm3 (24L) at r.t.p (298K/25C and 1atm/100kpa)

Question 8

Standard temperature and pressure

Answer 8

One mol of any gas occupies 22700 cm3 (22.7L) at s.t.p (273K/0celsius and 1atm/100kpa)

Question 9

When is real gases similar to the ideal gas?

Answer 9

Real gases closely approximate ideal gases when they are at low pressure (increases distance) and high temperature
(more random motion). Overall, reduces effectiveness of intermolecular attractive forces.

Question 10

pressure

Answer 10

particles colliding on the walls / boundaries of the container

Question 11

Ideal gas

Answer 11

1.no volume
2. no intermolecualr foce except when they collids
3. Gas particles are in a state of continuous random motion
4. Collisions are perfectly elastic (no loss of kinetic energy)
5. Absolute temperature is proportional to Kinetic Energy of the particles

Question 12

real gas

Answer 12

1. volume
2. intermolecular force
3. attractive force between the particle and the wall

Question 13

units for volume of gas

Answer 13

1000cm3=1dm3
100dm3=1m3

Question 14

Boyles law

Answer 14

for fixed mass/moles of any gas at a constant temperature. its volume is inversely proportional to its pressure

Question 15

Draw the graphs of Boyles law

Answer 15

Question 16

Charles Law

Answer 16

for fixed mass/moles of any gas at a constant temperature. its volume is inversely proportional to its pressure

Question 17

Draw the graph of Charles law

Question 18

avogadros consant

Answer 18

The mole is the Sl unit of amount
of substance. One mole contains
exactly 6.022 x 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA.

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Question 19

How do you convert grams to number of particles?

Answer 19

Question 20

Relative formula mass

Answer 20

Relative formula mass, Mr, is the sum of the weighted average of the atoms of an element ina formula unit relative to 1/12 of an atoms o carbon12

Question 21

mols formula

Answer 21

Question 22

Calculating empirical formula

Answer 22

For empirical formula, first divide percentage mass or mass by RAM, then divide by the smallest one

Tip: Case 1: percentage composition given➟assume 100 then convert to grams

Question 23

Describe the procedure for magnesium oxide experiment

Answer 23

1) Weigh the crucible with the lid (mass 1) and then the magnesium inside the crucible with the lid (mass 2).

2) heat the crucible until you see no further reaction. Oxygen has reacted with magnesium to make magnesium oxide

3)Turn off the Bunsen burner and allow the apparatus to cool.

4) Re-weigh the crucible with the lid containing the product (mass 3)

Question 24

What are limitations to the magnesium oxide experiment

Answer 24

1) Soot
2) magnesium oxide & magnesium nitrate production

Question 25

Combustion analysis

Answer 25

Question 26

water of crystallization

Answer 26

fixed ratio of molecules of water, known as water of cristallyzation, within the crystalline structure of the compound. The water of cristallyzation can be driven off by heating, and the change in mass used to calculate the ratio of water molecules to the anhydrous salt.

Question 27

limiting reagent

Answer 27

Step 1) Find number of mols of each reactant
step 2) Divide by the mol coefficient
step 3) Compare to determine the smallest number as the limiting reagent

Question 28

Avogadro’s law

Answer 28

Equal volumes of all gases, when measured at the same temperature and
pressure (STP), containing an equal number of particles.

Question 29

Gay Lussac law

Answer 29

For fixed mass/moles of any gas at a constant volume, its pressure is directly proportional to the temperature

Question 30

The combined gas law

Answer 30

Question 31

universal gas constant

Answer 31

Constant 𝑃𝑉/T is directly proportional to the fixed mass of the gas, or the
number of moles, n, introducing the constant, R

Pa x M3/molk = 8.31 Pa M^3 mol-1 K-1
kPa x dm^3 / molK = 8.31 kPa dm^3 mol-1k-1

Question 32

Density ideal gas equation

Answer 32

Question 33

molar mass ideal gas equation

Answer 33

Question 34

ideal gas equation

Answer 34

-P: Pressure in kilopascals (kPa) In IB convert to Pa
- V: Volume decimeters cubed (dm3) In IB convert to m3
- n: Number of moles
- T: Temperature in kelvin
- R: 8.31 (Universal gas constant)

Question 35

molar volume

Answer 35

The volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure

Question 36

volume of a gas at STP

Answer 36

Question 37

molar concentration equation

Answer 37

Question 38

dilution equation

Answer 38

Question 39

Adding solution method given concentration and volume of two solutions

Answer 39

calculate the new amount of mols by adding the number of moles from each individual solution, then find the new volume

Question 40

Avogadros equation

Answer 40

Question 41

Explain the graph

Answer 41

a. PV/nRT=1: The real gas behaves like ideal gas at low pressure and high temperature. The gases deviates at high pressure and low temperature.

b. PV/nRT>1: the volume of the gas particle is not negligible ➡ When pressure is higher than ideal gas, there are more collision with the wall as percentrage of volume of gas decreased

c. PV/nRP<1: there is attractive forces betwen the particle ➡ When the pressure is lower than ideal gas, there is attractive forces from other particles reducing the frequency of collision with the wall

Question 42

Draw the charles graph

Answer 42

Question 43

Draw Boyles graph

Answer 43