2.1 Foundations In Chemistry 2.1-3.4

Question 1

Isotopes

Answer 1

Atoms of the same element with different numbers of neutrons

Question 2

1 picometer

Answer 2

1 x 10^-12 m

One trillionth of a metre

Question 3

Physical and chemical properties of isotopes

Answer 3

Chemical properties stay the same because electronic configuration doesn’t change

Physical properties of the isotopes are influenced by the number of neutrons so are different (mass)

Question 4

Relative masses of p n and e

Answer 4

P 1
N 1
E 1/1800 (~0)

Question 5

Relative charges of p n and e

Answer 5

P +1
N 0
E -1

Question 6

Mass spectrometer

Answer 6

A machine that chemists can use to determine the relative atomic mass or relative molecular mass, the molecular formula, and the structure of compounds

Question 7

What does a mass spectrometer do

Answer 7

Sorts positively charged ions according to their mass and charge

Question 8

4 stages of mass spectrometry

Answer 8

Ionisation
Acceleration
Deflection
Detection

Question 9

Stage 1 Ionisation mass spectrometry

Answer 9

A sample is placed in the mass spectrometer, if it’s not already a gas it’s vaporised
The atoms or molecules diffuse into the path of electrons from the electron gun and are ionised
X(g) —> M^+(g) + e^- Or
X(g) + e^- —> X^+ (g) + 2e^-
+2 ions can be formed but are not as common as more energy is required to knock out two electrons

Question 10

Stage 2 acceleration mass spectrometry

Answer 10

A negative electric field is used to accelerate the beam of positive ions, and skits are used to narrow the beam

Question 11

Stage 3 deflection mass spectrometry

Answer 11

A strong magnetic field is used to deflect the positive beam
The amount each ion is deflected by depends on the mass to charge ratio, m/z
A small m/z ratio creates a larger deflection
By varying the magnetic field, ions of different m/z ratio can travel along the centre of the mass spectrometer

Question 12

Stage 4 detection mass spectrometry

Answer 12

When an ion reaches the detector it produces a tiny current which is noted as one ion with a specific m/z ratio
This is true for all the ions that reach the detector
Hence the proportion of each ion in the sample is recorded and the spectrum is printed

Question 13

Ar Definition

Answer 13

Average mass of an element relative to 1/12 of carbon-12

Question 14

Mr definition

Answer 14

Average mass of a molecule or compound relative to 1/12 of carbon-12

Question 15

Avogadro constant

Answer 15

The number of particles in each mole of carbon 12

6.02 x 1023 atoms

Question 16

One mole of carbon atoms has a mass of…

Answer 16

12g

Question 17

One mole of hydrogen atoms has the mass of…

Answer 17

1g

Question 18

Molar mass

Answer 18

Gives a convenient way of linking moles with mass
C = 12.0 g mol-1

Gives the mass in grams in each mol of the substance

Question 19

Molecular formula

Answer 19

The number of atoms of each element in a molecule

Question 20

Empirical formula

Answer 20

Simplest whole number ratio of atoms of each element in a compound

Question 21

Anhydrous

Answer 21

Without water

Question 22

Hydrated

Answer 22

With water

Question 23

Heating copper sulphate

Answer 23

Turns it from blue to white
The blue form contains water (hydrated copper sulphate)
The white form contains no water (anhydrous copper sulphate)

Question 24

Heating copper sulphate word equation

Answer 24

Hydrated copper sulphate <==> anhydrous copper sulphate + water

Question 25

Water of crystallisation

Answer 25

Compounds crystallised from water contain water molecules within the structure. The water is called water of crystallisation
Different compounds may contain different amounts of water of crystallisation

Question 26

What do we use to show how many molecules of water are associated with the compound (water of crystallisation)

Answer 26

We use a floating . followed by a number

Question 27

1cm3=?ml

Answer 27

1ml

Question 28

1ml=?cm3

Answer 28

1cm3

Question 29

Concentrated definition

Answer 29

A large amount of solute per dm3

Question 30

Dilute definition

Answer 30

A small amount of solute per dm3

Question 31

Weighing by difference

Answer 31

Weigh the empty wearing boat
Weigh out the desired amount onto it and record the mass (A)
Empty the weighting boat into a beaker
Reweigh the weighing boat and record its mass (B)
Do this sum B-A to work out the mass taken

Question 32

Molar gas volume

Answer 32

One mole of any gas occupies 245dm or 24000cm3 at room temperature and pressure

Question 33

1litre=?dm3

Answer 33

1dm3

Question 34

1dm3=?litre

Answer 34

1litre

Question 35

Ideal gas equation

Answer 35

pV=nRT

Pressure of gas (Pa) x volume of gas (m3) = no of moles of gaseous particles x gas constant x temp (kelvin)

Question 36

What’s the gas constant

Answer 36

8.31 J K-1 mol-1

Question 37

Absolute zero kelvin

Answer 37

-273oC

Question 38

Stoichiometry

Answer 38

In a balanced equations the balancing numbers give the ratio of the amount, in moles, of each substance
This ratio is called the stoichiometry of the reaction

Question 39

%yield

Answer 39

Actual yield / theoretical yield x 100

Question 40

Atom economy

Answer 40

Measure of how well atoms have been utilised

Mass of desires product / total mass of reactants x 100