Chem 171 Midterm 2 Refined

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Hydrogen formation by steam reforming
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CH4 +H2O-Ni->CO+3H2
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Hydrogen formation by water gas-shift reaction
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CO+H2O-Fe/Cu->CO2 +H2
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Hydrogen bond strength
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20 kJ/mol
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NaHCO3
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baking soda (bicarbonate of soda) – reacts with weak acid to form CO2 in bread
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NaCO3
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washing soda (provides carbonate in solution that precipitates Mg2+ )
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NaNO3, KNO3
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oxidizing agent in black gunpowder, also used in matches.
?25
The important reaction is:
2KNO3 + 4C -> K2CO3(s) + 3CO(g) + N2(g)
(produces lots of gas, so explosion occurs).
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Pure alkaline earths are made by..
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Dow Process. MgCl2 -> Mg2+ + 2Cl- -> Mg(s) + Cl2(g)
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thermite reactions
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(3BaO + 2Al -> Al2O3 + 3Ba) produces pure alkaline earths
(Al + Fe2O3 ->Fe + Al2O3)
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Alkali/alkaline earth metal salt differences
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many of the alkaline earth salts are not water soluble
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Mg(OH)2
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milk of magnesia. treats constipation
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MgSO4
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Epsom salts. pharmaceutical
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CaO
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quicklime, which reacts with water to give
slaked lime (Ca(OH)2). This is an inexpensive base that is used for agriculture
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concrete
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(gravel plus Portland cement). Portland cement is pellets of CaO mixed with gypsum, CaSO4-2H2O.
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Boron is mined as
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Na2B4O7•xH2O (x=10)
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Pure B can be used for
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the production of stiff, light fibers that are used in plastics
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BF3 BCl3
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(boron trihalide) is an industrial catalyst, acts as a Lewis acid
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NaBH4
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(sodium borohydride) is an important reducing agent
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Aluminum comes from
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bauxite (Al2O3•xH2O)
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Hall process
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electrolization of bauxite in the Hall process (1886) to give pure Al. Key to the Hall process is use of an alumina(Al2O3)/cryolite(Na3AlF6) mixture which gives a melt at 950°C rather than pure alumina (2050°)
for the electrolysis.
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Al2O3
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(alumina) has several crystal forms: alpha-Al2O3 is corundum, which shows up in sandpaper gamma-Al2O3 is used is chromatography for adsorption
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AlCl3 ·6H2O
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is used as a deodorant and antiperspirant (kills bacteria)
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Forms of pure C
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-Graphite (most stable, sp2 sheets)
-Graphene (single sheet)
-Diamond (tetrahedral, sp3)
-Fullerenes C60
-Nanotube
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CCl4, CHCl3, CH2Cl2
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(carbon tet, chloroform, methylene chloride) important solvents
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CF4
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Refrigerant
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CBr4
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fire extinguishing material
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SiC
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(silicon carbide or carborundum) is used as an abrasive
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Silicon: Can be made from
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SiO2 (sand) by reaction with graphite in an electric arc furnace
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By using ? it is possible to produce ultrapure Si
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zone refining
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Forms of silicon
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1. Silica (SiO2) used in making glass, ceramics
2. Silica gel (hydrated SiO2) used from chromatography media, and as a drying agent.
3. Aluminosilicates (replace Si4+ by some amount of Al3+ in silica). This has many forms, such as mica, feldspar, cements (after roasting with lime),
4. Silicone (-O-Si-O-Si-) used as lubricants and for waterproofing.
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Silicon applications
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1. Field effect transistors (discovered at Bells labs by Bardeen, Brattain, Shockley)
2. Solar cells (discovered at Bell labs by Pearson, Chapin, Fuller)
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Germanium
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is a semiconductor similar to Si, but much less important (although the first transistors were Ge)
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Tin
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Tin: produced from SnO2 by reaction with C. Used in tin cans
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Lead
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produced from PbS (galena) by oxidation, then reaction with C. Used on pipes, glazes, paint in the past, but now phased out because of toxicity. Significant uses now are in X-rays and lead-acid batteries
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Nitrogen
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Pure nitrogen is made by liquifying air, followed by fractional distillation. Its boiling temp is -196 °C, while oxygen (-183 °C) and argon (-186 °C) boil off.

Nitrogen has an oxidation number that ranges from +5 (in nitrates) to -3 (NH3 and nitrides).
N2 is a very stable substance (due to the triple bond) but nitrogen is also essential for life, and it is also actively involved in many chemical processes, so special procedures are necessary for fixing nitrogen.

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Industrial process to make ammonia is..
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the Haber process, and it involves the reaction N2 + 3H2 ->3NH3 (performed at high temperature and pressure and with an iron catalyst).This produces 1.6 x 1010 kg of ammonia each year, and the ammonia that is produced is used in fertilizer, polymers, explosives and many other applications.
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Important nitrogen compounds
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1. NH3 (of course)
2. NH4NO3 explosive and fertilizer
3. NaN3 (sodium azide) This decomposes into Na and N2 when shocked. Used in air bags.
4. NO2 (nitrogen dioxide), NO (nitric oxide), N2O (nitrous oxide) These oxides of nitrogen show up in many places in modern life. NO2 is a component of smog, NO is used in biology for signaling, N2O is an anesthetic.
6. HNO3 (nitric acid), HNO2 (nitrous acid), HNO (hyponitrous acid) HNO3 is a strong acid that is used in making fertilizer. HNO2 is used in making nitrites (preservative)
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Phosphorous made from
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Ca3(PO4)2 by heating with C and sand
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The stable form of P is
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P4 (white phosphorous) ignites spontaneously in air. This changes into red phosphorous (chains of linked P4 tetrahedra) when heated in the absence of air. red phosphorous is less reactive, but still can be used in the striking surfaces in matchbooks.
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Phosphorous compounds
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1. PH3 (phosphine) poisonous gas used in organic chemistry
2. PCl3 and PCl5 used in the synthesis of pesticides, oil additives, flame retardants. 3. H3PO4 (phosphoric acid) used in soft drinks, detergents.
4. Superphosphate (fertilizer) is a mixture of CaSO4 and Ca(H2PO4)2
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The most important use of As
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GaAs lasers for CD players. Similarly InSb is another laser system. GaAs is also used in electronics applications as an alternative to Si
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Oxygen produced by
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fractional distillation of liquid air. Primarily used in steel manufacturing
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The other form of On is ozone
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O3. This is important in the stratosphere, being produced by photodissociation of O2 (O2 ->O + O followed by O + O2 -> O3), and serving to remove near UV light from solar radiation.
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Pure sulfur is
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S8, and it occurs in both monoclinic and rhombic forms
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Important sulfur compounds include:
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1. H2S
2. SO2, SO3
3. H2SO3, H2SO4 (the most heavily produced chemical – 4×1010 kg – in USA), used in production of fertilizer, petrochemicals, dyes, detergents.
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Fluorine produced by
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electrolysis of KF. It is a colorless gas (F2) that is highly reactive.
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CaF2 is an essential component of
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bone, including teeth. Not as soluble as chlorides
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Compounds include:
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1. SF6
2. UF6 (used for making nuclear reactor fuel)
3. HF the only weak acid of the hydrogen halides, used for etching of electronic components in the electronics industry.
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Chlorine manufactured from
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electrolysis of NaCl
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Cl2 is
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a pale yellow-green gas, used as an oxidizing agent. Chlorine can have oxidation numbers from -1
to +7.
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Compounds include:
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1. HCl (hydrochloric or muriatic acid) HCl is stomach acid.
2. HClO4 perchloric acid (rocket fuel)
HClO3 chloric acid,
HClO2 chlorous acid,
HClO (hypochlorous acid) active ingredient in Chlorox
CCl3 industrial solvent
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CCl4
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Chlorinated polymers (PVC)
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Bromine produced from
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chlorine via 2Br- + Cl2 -> Br2 + 2Cl- (red-brown liquid)
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Important compounds
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1. HBr
2. Same acids as with Cl.
(Used to make fire retardants)
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Iodine produced from
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2I- + Cl2 -> I2 + 2Cl- I2 is a black solid with a purple vapor.
It is also used in organic chemistry. It is essential for life (thyroid)
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Important compounds:
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1. HI (used for organic iodides)
2. Same acids as with Cl.
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Says that the ability of an element to be oxidized is ordered as follows
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Electromotive Series
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Rare gasses
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All monoatomic.

All produced by fractional distillation except He and Rn

He comes from natural gas wells in Texas

Rn is found naturally in the ground as a result of radioactive processes

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Helium is used for
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cryogenics, for blimps, for He-Ne lasers.
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Neon, krypton, xenon are used for
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lighting.
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Argon is used for
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welding in inert atmospheres.
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Krypton and xenon are used
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to make excimer lasers (shortest wavelength commercially available lasers)
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Colloid :
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particles (1 nm to 1) suspended in a solvent
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Aerosol
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Solid in gas (smoke)
Liquid in gas (fog)
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Sol/gel
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Sol: Solid in liquid (behaves like liquid) nanoparticles in solution

Gel: Solid in liquid (behaves like solid) hairproducts

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Emultion/Solid emultion
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emultion: liquid in liquid (salad dressing/mayo)

solid emultion: liquid in solid (ice cream)

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foam/solid foam
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foam: gas in liquid (shaving cream)
solid foam: gas in solid (insulation)
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Lanthanide Contraction
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Electrons move faster closer to nucleus due to stronger coulombic interaction between electrons/nucleus. Faster moving objects (fractions of speed of light) have more mass due to relativity…move closer to nucleus

Radius for Period 6 much smaller than expected for Period 6

More stable (reactivity decreases)

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Stereo isomers
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arise when atoms are permuted in a complex but all the bonds are the same. Possibilities are geometrical isomers and optical isomers. Geometrical isomers arise when the molecule is superimposable on its mirror image. Optical isomers are compounds that are mirror images.
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OH2
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aqua
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NH3
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ammine
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NO
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nitrosyl
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CO
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carbonyl
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(en)
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ethylene diamine (K2)
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(dien)
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diethylene triamine (K3)
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(ox)
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oxalato (K2)
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(EDTA)
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K6
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Scandium
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chemistry is similar to Al, with +3 oxidation number. Not useful as a metal because it reacts with water. However it is used as an alloy to strengthen Al.
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Titanium
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+4 oxidation number is dominant in compounds. Ti metal is used in aircraft (light weight). TiO2 (rutile) is white paint, also an important semiconductor, and as a photocatalyst (splitting water). BaTiO3 is piezoelectric (distorts shape when charged).
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Vanadium
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+5 oxidation number. V is used as an alloy in steel. V2O5 is an oxidant, used as a catalyst in H2SO4 production.
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Chromium
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+3, +6 oxidation numbers. It is the red color of ruby in Al2O3. +3 state is essential for life (required for insulin to work, although the mechanism and the connection with diabetes is not known). Chromium is available in foods (certain meats, mushrooms, wheat germ, broccoli) and it is available is dietary supplements. +6 state is carcinogenic when airborne. This was featured in “Erin Brokovitz”. Cr metal used in steel (stainless is 12% Cr in Fe), and for plating. CrO2 is a ferromagnetic material used in tapes. Na2Cr2O7 is an oxidizing agent.
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Manganese
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+2, +4, +7 oxidation numbers. Responsible for the color of amethyst. Used as a strengthening alloy in steel. MnO2 is key component of batteries. KMnO4 is an oxidizing agent.
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Iron
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+2, +3 oxidation numbers. 5.6% of the earth’s crust. 3g in the body, mostly as hemoglobin. Used in steel.
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Cobalt
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+2, +3 oxidation numbers. Present in vitamin B12. Used in steel. Magnets contain Fe, Ni, Co, Al.
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Nickel
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+2, +3 oxidation numbers. Alloy in steel. Nickels are 75% Cu (because Ni is relatively rare).
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Copper
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+1, +2 oxidation numbers. 0.0007% of earth’s crust. Cu replaces Fe for oxygen transport in some animals. Used in bronze (10% Sn, 5% Pb, 85% Cu), brass (60% Cu), pennies.
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Zinc
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+2 oxidation number. 0.007% of earth’s crust. Present in many enzymes. Galvanized metal is zinc coated. Used in batteries.
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Steel manufacturing
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The important part involves the reduction of iron ore (Fe2O3 and FeO) to Fe by CO.

Limestone is added to convert impurities (silicates, aluminosilicates) into a molten mixture called slag that can be removed.
The iron that is made in a blast furnace is called pig iron. This has high carbon content, which makes the iron brittle.
To convert this into steel, the carbon is oxidized by adding oxygen and limestone, and then metals (Co, Ni, Mo, Mn, etc) are added.

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Iron in biology
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Hemoglobin, myoglobin (oxygen transport)

Oxygen binds to heme group to complete octahedron

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Copper in biology
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oxygen transport in octopus (hemocyanin)
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Zinc in biology
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carbonic anhydrase (hydrolyze CO2 to make HCO3-), carboxypeptidase (hydrolyzes peptides in digestion), alcohol dehydrogenase (converts alcohol to aldehyde)
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Molybdenum in biology
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nitrogenase is a Fe/Mo protein (nitrogen fixation)
This is part of the nitrogenase complex that also includes reductase (an Fe protein)

N2 +8e- +16ATP+16H2O

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gadolinium in biology
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magnetic resonance contrast agent (high spin)
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Nickel in biology
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urease, hydrogenase
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Cobalt in biology
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Vitamin B12. This compound contains the only C-Co bond in biology
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Alkali metals made by
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Down’s process: NaCl -> Na + Cl2
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t
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Col 1 + O2
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Li/Na/K form oxides -> M2O
Na w/ excess O2 form peroxides-> M2O2
Rb/Cs/Fr form superoxides -> MO2
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Col 1 + H2O
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M + H20 -> MOH + H2
reactivity increases as movement down column
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Col 1 + H2
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Form hydrides, MH…metal hydrides in water leave metal hydroxides, hydrogen bubbles out
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Col 2 + O2
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form oxides -> MO
Not Be
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Col 2 + H2O
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Form metal hydroxides -> M(OH)2
Not Be
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Col 2 + H2
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Form metal hydroxides, MH2

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