Module 2: Amount Of Substance Atoms Ions And Compounds

Question 1

What is the structure of an atom

Answer 1

Protons and neutrons in nucleus and electrons in shells

Question 2

What is the charge of a proton

Answer 2

+1

Question 3

What is the charge of an neutron

Answer 3

0

Question 4

What the charge of an electron

Answer 4

-1

Question 5

What is the mass of a proton

Answer 5

1

Question 6

What is the mass of a neutron

Answer 6

1

Question 7

What is the mass of an electron

Answer 7

1/1836

Question 8

What is the overall charge of an atom and why

Answer 8

Neutral because the total positive charge from protons is equal to the negative charge from electrons

Question 9

Definition for a mole

Answer 9

Amount of substance containing as many particles as there are carbon atoms in exactly 12g of the C-12 isotope

Question 10

definition for relative atomic mass

Answer 10

Weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom if C-12

Question 11

Definition for relative isotopic mass

Answer 11

Weighted mean mass of an atom of an isotope when compare to 1/12th mass of an atom of C-12

Question 12

What molar mass

Answer 12

Mass mole of a substance (g mol-1)

Question 13

Definition for relative molecular mass

Answer 13

Weighted mean mass of a molecule compared to 1/12 of the mass of an atom of C-12

Question 14

What’s avogadros constant

Answer 14

Number of atom per mole of the C-12 isotope (6.02 x 10^23 )

Question 15

How do you do a reacting mass calculation when given 1 mass

Answer 15

Whilst using balanced equation and correct units
1. Mole of known (mol = mass/mr)
2. Mole of unknown (mole ratio)
3. Mass of unknown (mass = mol x mr

Question 16

What is the solid equation for moles

Answer 16

Mole= mass (g) / Mr

Question 17

What is a limiting reagent

Answer 17

Substance in reaction which runs out first

Question 18

How do you do a limiting reagent mass calculation when given 2 masses

Answer 18

Using balanced equation and correct units
1. Mol of both reagents (mol = mass/mr)
2. Find limiting reagent
3. Mol of unknown (mol ratio)
4. Mass of unknown (mass =mol x mr )

Question 19

What’s an empirical formula

Answer 19

Simplest whole number ratio of atoms present in a compound

Question 20

What molecular formula

Answer 20

Number of atoms of each element in a molecule

Question 21

How to calculate empirical formula

Answer 21

1. Table with each element
2. Write % or mass (g)
3. Find moles of each elements (mol=mass/mr)
4. Find whole number ratio (divide by smallest)
5. Formula

Question 22

What does anhydrous mean

Answer 22

Substance that contains no water molecules

Question 23

What dies hydrated mean

Answer 23

Crystalline and containing water molecules

Question 24

What is water of crystallisation

Answer 24

Water molecules that form essential part of the crystalline structure of a compound

Question 25

How do you calculate formula for a hydrated salt

Answer 25

1. Moles of anhydrous (mol=mass/mr) 2 moles of water (mol=mass/mr) 3. Ratio to find formula (empirical method)

Question 26

What is the practical for water of crystallisation

Answer 26

-mass of crucible -mass of crucible and hydrated salt -heat until constant mass (reweigh x2) -record mass -mass of anhydrous -find formula

Question 27

Equation for moles in solution

Answer 27

Moles=conc (mol dm-3) x vol (dm^3)

Question 28

Equation for moles in gas

Answer 28

Moles = vol(dm^3) / 24

Question 29

What has to be for mol = vol/24 to be true

Answer 29

Room temp of 298K and room pressure (101kPa)

Question 30

What’s the ideal gas equation

Answer 30

pV = nRT

Question 31

What’s p in pV = nRT

Answer 31

Pressure in Pa

Question 32

What’s V in pV = nRT

Answer 32

Volume in m^3

Question 33

What’s n in pV = nRT

Answer 33

Number of moles

Question 34

What’s R in pV = nRT

Answer 34

Ideal gas constant of 8.314 J mol-1 K-1

Question 35

What’s T in pV=nRT

Answer 35

Temperature in K

Question 36

How do you convert °C to K

Answer 36

+ 273

Question 37

Percentage yield equation

Answer 37

% yield = actual yield (mol of product) —————————————- ——-x 100 Theoretical yield (mol of products

Question 38

What can result in lowered percentage yield

Answer 38

-incomplete reaction -side reaction -impure substance -loss through transference

Question 39

What is atom economy

Answer 39

Measure of what proportion of a reaction are the desired product and how much is waster

Question 40

Atom economy equation

Answer 40

Mass of desired product —————————————x 100 Total mass of product

Question 41

What is true for atom economy if only 1 product

Answer 41

100% atom economy and is ideal

Question 42

What can be used to analyse different elements

Answer 42

Mass spectrometry

Question 43

What can mass spectra show

Answer 43

Relative isotopic masses and abundances

Question 44

What is on the axis for mass spectrum

Answer 44

X axis- mass/charge Y axis -%isotope abundance

Question 45

What is the equation for relative atomic mass

Answer 45

(% x isotopic mass) + ( % x isotopic mass) ——————————————————— 100