Colour By Design

Question 1

Atomic emssion spectra

Answer 1

Laser microspectral analysis (LMA) is used to produce a type of emission spectrum to analyze pigment samples

Question 2

Attaching dyes to fabrics:
Direct dyes 
Acid dyes 
Other dyes 
Fibre-reactive dyes

Answer 2

Direct dyes - attach to cotton via h bonding
Acid dyes attach to protein fibers eg silk via ionic bonds
Other dyes attach to fabrics using a mordant - this forms a complex, linking fibre and dye together
Fibre reactive dyes - strong covalent bonds with cotton fabrics.

Question 3

Stronger the bond between fabric and dye…

Answer 3

The more colour fast the dye will be

Question 4

Oils and fats are naturally occurring ________ of _______ and ______

Answer 4

Triesters
Propane-1,2,3-triol (glycerol)
And long-chain carboxylic acids

Question 5

Fatty acids are the ______ in fats and oils

Answer 5

Carboxylic acids

Question 6

Fatty acids facts and bits

Answer 6

Even number of carbons (16/18)
Unbranched carbon chain
Can be saturated (only C-C) or unsaturated (mix of both or just C=C)

Question 7

Triesters from largely saturated fatty acids are _____ as there is better packing of the molecules resulting in stronger intermolecular bonds
Largely unsaturated are ___

Answer 7

Solids or fats

Liquids or oils

Question 8

Hydrolysis of esters

Answer 8

Broken down to sodium salt of the fatty acid (soap) and glycerol by heating with dilute NaOH.
IF FREE ACID IS REQUIRED TREAT SODIUM SALT WITH dilute HCL

Question 9

Hydrogenation of unsaturated oils

Answer 9

Addition of H, using a nickel catalyst and the correct conditions produces more saturated solid fat. Not all c=c bonds are saturated so gives spreadable fat, still polyunsaturated. Eg of heterogenous catalysis

Question 10

Molecules that only absorb UV light and transmits all others

Answer 10

Appear colourless as our eyes can’t detect uv

Question 11

Conjugated system

Answer 11

Has alternate C=C bond to C-C. benzene rings and N=N bonds can also be part of conjugate system

Question 12

Absorption of uv or visible light causes ______

Answer 12

Electronic transitions - electrons move to higher energy levels and the molecules become excited

Question 13

Many unsaturated and conjugated systems absorb uv and visible light. The delocalised electrons —-

Answer 13

In these systems require less energy to become excited compared with electrons in single bonds

Question 14

UV - visible spectroscopy

Answer 14

Spectrometer scans a range of wavelengths of both UV and visible light. Instrument produces a spectrum.
Features of spectrum:
X axis shows wavelength measured in nano meters (1nm = 1X10^-9 m)
Y axis shows intensity of absorption, usually no units
Overall shape is important not individual peaks

Question 15

Interpreting spectrum from uv spectroscopy absorption

Answer 15

Find wavelength at which absorption is greatest - known as delta max. Colour of solution will be complimentary to this.

Question 16

Absorption is more intense and the wavelength of delta max increases for..

Answer 16

Organic molecules with large delocalised systems

Question 17

Reflectance spectra

Answer 17

Used for analyzing a substance that cannot be easily made into a solution. Uv and visible light is shine on the surface and and any reflected light is collected. Used for old paintings. Opposite to absorption spectra.

Question 18

Chromatography is a method…

Answer 18

Of separating and identifying the components of a mixture

. Eg components that make up old paintings.

Question 19

Chromatography depend on

Answer 19

equilibrium a set up between stationary phase and mobile phases. Components with a higher affinity for the stationary phase move more slowly.

Question 20

In G.L.C the stationary phase is _____

Mobile phase is _____

Answer 20

S- A non volatile liquid coated on the surface of finely divided solid particles. This material is packed inside a long thin column, which is coiled inside an oven.

Mobile phase - Unreactive carrier gas and carries mixture through the column.

Question 21

Examples of inert carrier gases

Answer 21

Nitrogen and noble gases

Question 22

How does a g.l.c record data

Answer 22

As each component emerges form the Column, a peak is recorded on the chromatogram. The area under each peak is proportional to the amount of that component mixture. Time that a component takes to emerge is called the retention time.

Question 23

Simplest aren’t is…

Answer 23

Benzene, C6H6, flat hexagonal structure with a bond angle of 120 degrees

Question 24

Arenas are

Answer 24

Hydrocarbons that contain benzene rings. Their names always end in -Ene, meaning they’re unsaturated.

Question 25

Who’s structure Is single - bond - single etc

Answer 25

Kekules

Question 26

Do arenes react with bromine water?

Answer 26

No as they don’t have any c=c bonds, the bonds are delocalised.

Question 27

Nitrous acid is unstable and made when needed by

Answer 27

Reacting NaNO2 with dilute HCL (aq)

Question 28

Diazonium ion general formula

Answer 28

R-N+=N

Bond between N is 3

Question 29

When are diazonium ions stable

Answer 29

When aromatic and even these must be made under temperatures of 5 degrees

Question 30

Diazotisation reaction -

Answer 30

formation of benzenediazonium ion
Conditions and reactants-
Phenylamine, dilute HCL and sodium nitrate (III) at temperature lower than 5 degrees.

Question 31

Diazonium ions are

Answer 31

Weak electrophiles, they will attack phenols and aromatic amines (coupling agents) as both are electron rich rings

Question 32

Coupling reaction

Answer 32

Formation of an -N=N- bond product is an azo compound. Between coupling agent and benzenediazonium ion

Question 33

Azo compound general formula

Answer 33

R-N=N-R, compounds with R groups are aryl groups are most stable.

Question 34

Uses of azo compounds

Answer 34

Aromatic azo compounds make excellent fade-resistant dyes. By attaching different functional groups to the chromophore, properties of molecule are modified.

Question 35

Transition metals and colour

Answer 35

Electrons in the D orbitals can be excited. When transition metal ion is surrounded by ligands the d orbitals ar split into two different energy levels.
Electrons in lower energy levels can be excited to the higher. The excitation energy required corresponds to absorption of visible light.

Question 36

Factors that could affect the excitation energy and therefore affect the colour :

Answer 36

Type of ligand
Shape of complex -octahedral or tetrahedral
Coordination number of complex
Charge on central transition metal ion

Question 37

In an isolated transition metal ion…

Answer 37

All the d orbitals and any electrons in them have the same energy

Question 38

If the d sub shell is empty or full

Answer 38

Transition metal ion is colourless

Question 39

Chromophore -

Answer 39

Part of the molecule responsible for any colour.

Is an extended delocalised system of electrons obtaining unsaturated groups