Hsc Marathon 2009 - Chemistry (4 Viewers)

[Pwnage101]

taking a stab-

(i)gamma emitter
(ii)water soluble. gamma emitter
(iii)able to chemically combine with certain cells, and gamma emitter, short half life
(iv)gamma emitter, short half life
(v)chemically combines with blood cells, gamma emitter
(vi)chemically combines with other elements(maybe oxygen) + reacts with smoke?
(vii)chemically combines with cells that concentrate in thyroid.

pretty unsure, tell me where i went wrong ta

describe and account for the many uses of ethanol as a solvent for polar and nonpolar substances

wouldn't (i) be a Beta emitter?

 

[bored of sc]

wouldn't (i) be a Beta emitter?

My information says either beta or gamma.

 

[scora]

wouldn't (i) be a Beta emitter?

pretty sure if it emmits gamma radiation, it can still be detected

 

[scora]

just out of curiosity, how come whenever i quote someone, their name doesn't show up

 

[Michaelmoo]

describe and account for the many uses of ethanol as a solvent for polar and nonpolar substances

Ethanol is considered an effective industrial and household solvent for both polar and non-polar substances. This property of ethanol can be understood when observing its molecular structure.

One end of the ethanol molecule consists of a Hydroxyl group (OH) and is considered a polar end . The O-H bond is considered polar as oxygen is much more electronegative than Hydrogen. Consequently, the group is able to form strong hydrogen bonding between other polar substances such as water.

On the other end, there is a non-polar ethyl group (C2H5) which is overall non-polar in nature, and consists of non polar C-C and C-H bonding (due to little difference in electronegativity). This end is able to readily attach and form dispersion forces with other non-polar molecules, thus the dissolution.

From this it can be deduced that ethanol is one of the most important solvent in the modern 20th century. With many applications such as oils, cosmetics, medicinal preparations and cleaning agents; ethanol is only the second after the universal solvent itself water.


Question
Identify one device that allows the detection of radiation and describe its operation

 

[x.Exhaust.x]

Ethanol is considered an effective industrial and household solvent for both polar and non-polar substances. This property of ethanol can be understood when observing its molecular structure.

One end of the ethanol molecule consists of a Hydroxyl group (OH) and is considered a polar end . The O-H bond is considered polar as oxygen is much more electronegative than Hydrogen. Consequently, the group is able to form strong hydrogen bonding between other polar substances such as water.

On the other end, there is a non-polar ethyl group (C2H5) which is overall non-polar in nature, and consists of non polar C-C and C-H bonding (due to little difference in electronegativity). This end is able to readily attach and form dispersion forces with other non-polar molecules, thus the dissolution.

From this it can be deduced that ethanol is one of the most important solvent in the modern 20th century. With many applications such as oils, cosmetics, medicinal preparations and cleaning agents; ethanol is only the second after the universal solvent itself water.


Question
Identify one device that allows the detection of radiation and describe its operation

Strontium-90: Strontium-90 undegoes beta decay, finding it as an extensive use in medicine and industry e.g. radioactive source for tracers and for superficial radiotherapy of some cancers.

How would you distinguish between an alkane and an alkene?

 

[Kaatie]

photographic film, radiation exposes photographic film, the amount of darkening on the film is a good indicator of the amount of radiation present

describe the effect of transition metal catalysts on the polymerisation process

 

[xxstef]

How would you distinguish between an alkane and an alkene?

when combined with bromine water (brownish in colour), alkenes will decolourise to colourless quickly, but alkanes take longer and need light.

Outline the difference between alpha, beta and gamma radiation.

 

[Kaatie]

dam got beaten. alkane has a single bond, alkene has a double bond, was that the answer you were looking for? my next question is above

 

[Kaatie]

got beaten again lol
alpha can only penetrate few cm of air
beta can only penetrate few mm or Al
gamma can only penetrade several cm of Pb

my question is above

 

[Pwnage101]

pretty sure if it emmits gamma radiation, it can still be detected

pretty sure it's Beta, like strontium-90

cause gamma would go straight through, despite a, for eg, 10 mm increase in thickness, however beta has less penetration and thus will still make it through air (unlike alpha), but will be affected by changes in thickness

(see http://science.uniserve.edu.au/school/curric/stage6/chem/isotopes.xls - search 'thickness gauge' - all the one's that show up are beta emitters)

(also, "Since you said you are measuring coating thickness, I am judging that the thicknesses are relatively small and the source is probably a beta emitter, and the most common of these is strontium-yttrium-90. If the detector is a thin window type, designed for beta measurements...." from Dose from thickness gauge radiations)

 

[jet]

Outline the difference between alpha, beta and gamma radiation.

Alpha radiation is the emission of a helium nucleus from the nucleus. It occurs for any atom above atomic number 83, or if the electromagnetic forces in the nucleus are too strong.

Beta radiation is the emission of an electron from the nucleus when a neutron is converted to a proton. This occurs when there are too many neutrons in the nucleus.

Gamma radiation is the emission of energy from the nucleus which aids in the removal of excess energy. it often accompanies other processes of radioactive decay.

Describe the conditions under which a nucleus can be unstable

 

[Kaatie]

alpha- too many protons and neutrons
beta- neutron/proton ratio too high
positron- neutron/proton ratio too low
gamma-excess energy

what is a free radical

 

[Timothy.Siu]

something with an unpaired electron which makes it very reactive.

why would you saturate the salt bridge in a galvanic cell with potassium nitrate?

 

[Kaatie]

Potassium ions (K+) and (NO3-) ions do not form insoluble precipitates with other ions, not sure if that is correct you will have to tell me if im right or wrong.

what is the general formula for an alkane and an alkyne

 

[singh.with.me]

general formulae:
alkane: C(n)H(2n+2)
alkyne: C(n)H(2n-2)
and if u want alkene: C(n)H(2n)

list all * the polyatomic ions - include charges

*(edit: the ones that we need to know)

 

[Kaatie]

OH - -1
SO4 - -2
SO3 - -2
CO3 - -2
PO4 - -3
NO3 - -1
NO2 - -1
CN - -1
NH4 - 1
HCO3 - -1
HSO4 - -1
HSO3 - -1
HPO4 - -2
H2PO4 - -1

what is a substitution reaction

 

[x.Exhaust.x]

Potassium ions (K+) and (NO3-) ions do not form insoluble precipitates with other ions, not sure if that is correct you will have to tell me if im right or wrong.

I think that's wrong. A salt bridge required for the galvanic circuit to be completed, and to maintain electrical neutrality

 

[Kaatie]

i think she was asking why postassium nitrate not another chemical not why would you use that salt bridge

 

[scora]

^ lol ,pretty sure timothy's a guy's name- so yeah.

summarise the chemistry of the fermentation process