Short Answer Questions for SAH Finals 2001-2004
Terms
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- Carbon
- C
- Zinc
- Zn
- Fe
- Iron
- Cobalt
- Co
- Mn
- Maganese
- Nitrogen
- N
- Ca
- Calcium
- Name two elements that prefer to form ionic bonds with other elements.
- Sodium and Potassium
- Define the 'octet' rule of atomic theory.
- Each atom is trying to get 8 electrons in its outer shell.
- Name one element that is solid at room tempreture and one that is liquid.
- Silver is solid at room tempreture and mercury is liquid.
- Calcium Carbonate
- CaCO(sub3)
- Acetone
-
O
II
CH(sub3) - C - CH(sub3) - Sulphuric Acid
- H(sub2)SO(sub4)
- Glucose
- C(sub6)H(sub12)O(sub6)
- What is the structural formula of Acetone?
-
H O H
I II I
H - C - C - C - H
I I
H H - What is the electrical charge of an electron? Where is the electron found in an atom?
- The electrical charge of an electron is -1 and the electron is found in energy levels outside the nucleous of an atom.
- In order to make a change in physical state (turning a solid into a liquid for instance), or for a chemical reaction to take place, what needs to be present? Give two examples of forms this added ingredient can take.
- A catalyst is needed and can be heat or magnesium to name two.
- What is the primary bonding prevalent in salts? Why does this type of bonding form in water?
- Ionic bonding, because of the breakdown into ions when salts are put in water and because of the compatability of polar covalent bonding and ionic bonding.
- Name three types of intermolecular forces.
- Van der Waals, Dipole and Hydrogen Bonding.
- Describe how hydrogen bonding contributes to the 'like dissolves like' rule, using an example of an artist's material.
- Hydrogen bonding is present in water it gives water the ability to dissolve sloutes that have hydrogen bonding such as gum arabic.
- If the difference between the refractive indices of a pigment and a medium is small, would you expect the pigment to be opaque or transparent?
- Transparent
- What is refraction?
- The bending of light as it passes from one medium to another.
- Visible light (400nm - 760nm) is part of the electro-magnetic spectrum. Name two other forms of radiation which are part of the electro-magnetic spectrum.
- UV and Infrared.
- Name two properties of light.
- Reflection and Refraction.
- Prussian Blue
- inorganic
- Barytes
- inorganic
- Gamboge
- organic
- Synthetic alizarin crimson
- inorganic
- Azurite
- inorganic
- Synthetic Ultramarine
- inorganic
- Copper Phthalocyanine
- organo-metallic
- Cadmium Yellow
- inorganic
- Define the class of compounds known as carbohydrates? Give two examples of artists materials that can be primarily classed as carbohydrates.
- Carbohydrates are the most abundant organic material on the earth's surface because of cellulose and and starch. Carbohydrates are built up through a combination of water and carbon dioxide. Two examples of artists materials that we primarily class as carbohydrates are paper and gum arabic.
- Certain reactions cause polymers to become more rigid, to have higher melting points and changes in solubility. This is caused by the development of a new chemical feature. What is this feature? Give one example of a painting material where this occurs.
- Crosslinks which occur in the drying of oil paints.
- Name one pigment that fades with light. Explain briefly why this occurs.
- Indigo fades with light because it undergoes steady oxidation when exposed to light.
- Name two possible features of materials which make them susceptible to degradation reactions.
- Materials composed of unsaturated hydrocarbons are susceptable to to pollutants, while materials with unstable crystaline structures such as vermillion are suceptable to darkening.
- Zn
- Zinc
- K
- Potassium
- Chromium
- Cr
- Tin
- Sn
- Mg
- Magnesium
- Helium
- He
- Ag
- Silver
- Name two elements that form covalent bonds with other elements.
- Carbon and Oxygen
- Name the three particles within an atom.
- Proton, Neutron, Electron
- Define a solution.
- A mixture that is homogenous to the molecular level.
- Briefly describe the 'like dissolves like' rule, using an example of an artist's material.
- Solvents that are chemically similar to solutes will usually dissolve them, as is the case with water and gum arabic.
- If the difference between the refractive indices of a pigment and a medium is large, would you expect the paint to be opaque or transparent.
- Opaque
- When the surface of a varnish is hazy, what is happening to the visible light hitting it?
- It is scattering.
- Which part of the electromagnetic spectrum is the most damaging to organic materials? What is the approximate wavelength band of this light?
- UV, 100nm-400nm
- Chalk
- inorganic
- Red Lead
- inorganic
- Alizarin Crimson
- organic
- Vermillion
- inorganic
- Azo Yellow
- organic
- Orpiment
- inorganic
- Rose Madder
- organic
- Define the chemical characteristics of the class of compounds known as proteins. Give two examples of artists' materials that can be primarily classed as protein-based.
- They are stable to oxidation. Change very little chemically under normal conditions of temperature and humidity. Moisture causes hydrolosis of the peptide linkages lowering average molecular weight, allowing bacteria and fungi to flourish. Peptide and cystine linkages are broken by UV light. Two examples of artists materials that can be primarily classed as protein-based are egg and animal glue.
- Why are double and triple bonds reactive sites?
- Because of the prescence of pi-bonds which make it easier to share electrons.
- What are the chemical 'bridges' formed between polymeric structures called? How do they affect the properties of the polymer?
- Cross links. Cross links make polymers more solid or rigid and slow movement at the molecular level.
- Give two examples of pigments that are affected by atmospheric pollution. What are the polluting agents in these cases?
- Lead white which goes black in the prescense of sulphur dioxide and where Azo Yellow is degraded by nitric oxide.
- Name the two ways paint can dry. Provide an example of an artist's material for each process.
- Linseed oil based paints is an example of a paint that dries by chemical reaction between the paint and something else. Egg tempra paints are an example of paints that dry by chemical reaction between ingredients in the paint.
- Al
- Aluminium
- Oxygen
- O
- Cu
- Copper
- Lead
- Pb
- Potassium
- K
- Hg
- Mercury
- Sulphur
- S
- Ti
- Titanium
- Name two non-metallic elements.
- Carbon and Sulphur
- Name two gaseous elements which prefer to exist as diatomic molecules.
- Oxygen and Chlorine.
- Calcium Sulphate
- CaO(sub4)S
- Iron (II) Oxide
- FeO
- Ethanol
- C(sub2)H(sub5)OH
- Lead(IV) Oxide
- PbO
- What is the electrical charge of a neutron? Where is it found in the atom?
- The charge is 0 and it is found in the nucleous.
- What is the random motion of particles called? Give an example to describe the phenomena.
- Brownian motion. Smoke in air.
- Name two types of primary bonding found in atoms and molecules.
- Ionic and Covalent.
- What type of primary bonding is prevalent in organic molecules?
- Covalent
- Name three types of intermolcular forces.
- Van der Waals, Dipole Forces and Hydrogen Bonding
- Give an example of hydrogen bonding, discussing the physical and chemical properties associated with it.
- Hydrogen bonding is present in water and gives it many of its unique properties, such as high boiling point, high surface tension and low density in its solid form.
- Describe why linseed oil will not dissolve in water and ethanol will.
- Ehthanol will dissolve in water because of the "like dissolves like rule." Ethanol, like water has polar covalent bonding, while linseed oil does not, making it dissimilar to water.
- What color would you expect to see if light is reflected at 510 nm?
- Green
- What color would you expect to see if light is absorbed at 510 nm?
- Red
- What wavelength of radiation causes the most damage to organic materials?
- UV
- Lead White
- inorganic
- Indigo
- organic
- Copper Phthacyanine
- organo-metallic
- Alizarin
- organic
- Mars Red
- Inorganic
- Gum Arabic
- carbohydrate
- Linseed Oil
- fatty acid
- Casein
- protein
- Animal Glue
- protein
- Acrylic Emulsion
- co-polymer
- Bees Wax
- Wax
- What is the chemical process of forming a dry paint film called? What are the small repeating units called.
- Polymerization and monomers.
- Methane (structural formula)
-
H
I
H - C - H
I
H - Propanol (structural formula)
-
H H H
I I I
H - C - C -C - O - H
I I I
H H H - Ethanoic Acid (structural formula)
-
CH(sub3) - C - H - C =O
I I
CH(sub)3 OH - Name a pigment that is known to slow down the drying rate of linseed oil, one that is known to cause drying cracks and one which contributes to faster drying.
- Van Dyke Brown causes drying cracks, cobalt blue speeds up drying and bitumen slows drying down.
- Name two types of degradation reactions found in paintings, give examples of artists' materials where these reactions are likely to occur.
- One type of degradation reaction is the breakdown of polymeric structures caused by free radicals. This occurs with zinc-oxide white, another type is the yellowing of linseed oil based paintings that are stored in the dark.
- Chlorine
- Cl
- Iron
- Fe
- H
- Hydrogen
- Name two metallic element.
- Silver and Gold
- Name two gaseous elements.
- Hydrogen and helium.
- Name an element which is liquid at room tempreture.
- Mercury
- What two types of bonding can one find within a molecule.
- Ionic and covalent.
- Give one example of each type of bonding, decribing the physical and chemical properties associated with each type of bonding.
- Metallic bonding is seen in brass and is an extremely strong type of bonding. In it, positively charged ions push so close together that electrons form a cloud, some hug the nucleous, but many are free in the valence shell. This accounts for metals' reactivity and maleability. Covalent bonding is seen in water where electrons are shared between elements. Covalent bonds are relativly weak and create subtances with low boiling and melting points that do not conduct electricity and do not have crystalline structures. Ionic bonds are relatively strong bonds as can be seen in NaCl table salt. This is due to the attraction between posative cations and negatvie anions present in all ionic bonds. As a result ionic bonds have high boiling and melting points and conduct electricty in water, where they seperate into ions.
- Describe the principle of "like dissolves like." Give one example.
- A solute with similar composition to s a solvent will probably dissolve in that solvent. Such as ethanol dissolving in water.
-
Organic molecules composed of many repeating units (monomers) are called?
Give one example from paintings - polymers, alkyd paints
- Certain reactions cause polymers to become more rigid and have higher melting points. These polymers have become? Give one example from a painting.
- Cross linked. Drying oil paints form cross links, creating a paint film.
- Which wavelengths cause the most damage to organic materials and why?
- UV, because UV light aids in the creation of free radicals within organic materials which break up double bonds, causing problems in the paint film.
- What color would you expect to see if light is reflected at 555 nm?
- Yellow
- What color would you expect to see if light is absorbed at 555 nm?
- Dark Blue
- Describe diffusion and give one example.
- Diffusion is the movement of fluid from an area of high concentration to an area of low concentration which occurs until equilibrium is reached. An example is when dye is added to water.
- Why does hydrogen bonding make water such a unique solvent?
- Because hydrogen bonding is the strongest form of intermolecular forces allowing water to decrease the ability of molecules of solute to precipitate out of the solution.
- What is the difference between a compound and a mixture?
- A compound is compsed of different kinds of atoms that are chemically bonded, wheras a mixture is a physical combination that can be no more homogenous then the molecular level.
- Mineral pigments appear colored for several reasons, name two.
- Because that are often transition metals in ligend fields and because they participate in charge transfers.
- What is a hydrocarbon? Give two examples of hydrocarbons which are associated with paintings.
- A hydrocarbon is an element consisting of hydrogen and carbon. Two examples associated with paintings are stoddard solvent and bitumen.
- Why are double and triple bonds so reactive?
- Because of the prescense of pi-bonds, making electrons easy to share.
- What is the difference between an alcohol and an aldehyde?
- Aldehydes are formed by the partial oxidation of primary alcohols.
- What is the difference between methanoic acid and ethanoic acid?
- Both are carboxylic acid form of methanol and ethanol respectivly. Menthanolic acid is HCOOH and Ethanolic Acid is CH(sub3)COOH.
- Formula for alkanes.
- C(subn)H(sub2n+2)
- Acetic Acid
- CH(sub3)COOH
- Carbonic Acid
- H(sub2)CO(sub3)
- Hydrochloric Acid
- HCl
- Nitric Acid
- HNO(sub3)
- Ethane
- C(sub2)H(sub6)
- Benzene
- 6 conjugated carbon atoms single bonded to hydrogen atoms
- acetic/carboxylic acid
-
O
II
CH(sub3) - C - OH - high frequency
- short wavelength
- short wavelength
- high frequency
- wavelength of 100 to 400nm
- UV
- wavelength of 400 to 700nm
- visible
- wavelength of 750 to 1000nm
- infrared
- violet (wavelength)
- 400-420nm
- dark blue (wavelength)
- 420-450nm
- blue-green (wavelength)
- 450-490nm
- green (wavelength)
- 490-520nm
- yellow-green (wavelength)
- 530-545nm
- yellow (wavelength)
- 545-580nm
- orange (wavelength)
- 580-630nm
- red (wavelength)
- 630-720nm
- violet 400-420nm
- yellow-green 530-545
- yellow-green 530-545
- violet 400-420nm
- red 630-720nm
- green 490-530nm
- green 490-530nm
- red 630-720nm
- blue green 450-490
- orange 580-630nm
- orange 580-630nm
- blue green 450-490
- yellow 545-580nm
- dark blue 420-450nm
- dark blue 420-450
- yellow 545-580nm
- pollutants
- NO(sub2) and SO(sub2)