Question Chain Thread !!! (2 Viewers)

[Undermyskin]

Um, why are they dissolved? Isn't it ice?

 

[JasonNg1025]

For the last dot point, also concentrations are like max 0.001ppm which is heck hard.

Second point, what's the equation? I've always thought it to be

2NH₄⁺ + 2e^- --> 2NH_{3 (g)} + H_{2 (g)}

2MnO_{2 (g)} + H_{2 (g)} --> Mn₂O_{3 (s)} + H₂O _(l)

But is it now Mn₂O₃ forming a hydroxide of some sort?

 

[danz90]

Um, why are they dissolved? Isn't it ice?

Probably some dry deposition bullshit lol

For the last dot point, also concentrations are like max 0.001ppm which is heck hard.

Second point, what's the equation? I've always thought it to be

2NH₄⁺ + 2e^- --> 2NH_{3 (g)} + H_{2 (g)}

2MnO_{2 (g)} + H_{2 (g)} --> Mn₂O_{3 (s)} + H₂O _(l)

But is it now Mn₂O₃ forming a hydroxide of some sort?

Yeah exactly. Manganese is a transition metal, and its oxide will form a basic solution (just like all transition metals except ZnO, which is amphoteric). And when you combine the two, you get the overall reduction equation for the dry cell:

MnO₂(s) + NH₄⁺ + H₂O(l) + e^- ---> Mn(OH)₃(s) + NH₃(aq)


I just gotta memorise the stupid reduction/oxidation equations for the button/silver oxide cell. They're so stupid.. involving freaking hydroxide ions and all, argh hate them.

 

[JasonNg1025]

I'm doing mercury oxide, is it similar

Zn_(s) + 2OH^- --> ZnO_(s) + H₂O + 2e^-

HgO_(s) + H₂O + 2e^- + --> Hg_(l) + 2OH^-

Ok I gotta go now
Cya

 

[JasonNg1025]

Which sulfur compound preserved food?

 

[qqmore]

Sulphur dioxide is used to produce sulphorous acid to preserve food such as pickles. It's low pH prevents the growth of microbes, allowing the food to stay fresher longer.

 

[Azreil]

Sulfur... dioxide? I can't remember that being in the course ><

Describe the structure of cellulose

 

[qqmore]

Can someone post up the correct oxidation/reduction reactions for DRY CELL and SILVER BUTTON cell

 

[JasonNg1025]

I think sulfuric acid "prevented the growth of microorganisms and bacteria which are sensitive to acids and cannot grow in an acidic environment"

That's what I just got from Dot Point

Cellulose (C₆H₁₂O₆) has a ring hexagonal structure made of 5 carbon atoms and an oxygen atom. There are OH and H groups above and below the ring. It has a CH₂OH group above, and in solution the ring can open forming a straight chain.

*Insert diagram here*

 

[qqmore]

Sulfur... dioxide? I can't remember that being in the course ><

Describe the structure of cellulose

Cellulose is a natural condensation polymer composed of thousands of glucose monomers. During condensation polymerisation, the beta glucose monomers link together by 1-3 glycosidic bond to form cellulose. This glycosidic bond forms when two -OH react and condense out a water molecule.

Celloluse is made up of straight and flat ribbon like strands due to the beta linkages between glucose monomers. It has a rigid structure and is a strong molecule. This is due to the close packing of the ribbons as well as the strong hydrogen bonds between hydroxide groups. It is insoluble in water due to strong hydrogen bonding.

and i would draw the diagram... just in case.

 

[danz90]

Sulfur... dioxide? I can't remember that being in the course ><

Describe the structure of cellulose

Cellulose is a natural condensatin polymer comprised of glucose monomers (up to 3000 per cellulose polymer). Adjacent Glucose monomers are positioned 180 degrees relative to each other, so bulky CH₂-OH groups do not interact with each other.
Each glucose monomer is joined by a beta-1,4-glycosidic linkage (ether linkage). Strands or polymer chains of cellulose are linked via hydrogen bonding (between polar -OH groups), permanent dipole-dipole forces, as well as dispersion forces - thus making cellulose commonly exist as tough, sturdy fibres.


EXPLAIN the term biopolymer, and identify an example.

 

[Azreil]

Can someone post up the correct oxidation/reduction reactions for DRY CELL and SILVER BUTTON cell

Zn(s) -> Zn2+(aq) + 2e-
NH4+(aq) + MnO2(s) + H2O(l) + e- -> Mn(OH)3 + NH3

Zn + 2OH- -> ZnO + H2O + 2e-
Ag2O + H2O + 2e- -> 2Ag + 2OH-

 

[qqmore]

Biopolymers are polymers created naturally occuring biomass such as cellulose. They have superior properties than normal synthetic polymers are they are biodegradable, renewable and biocompatible.

An example of a biopolymer is cellulose or starch. However, there have been developments to produce biopolymers such as PHB (aka biopol) to be used in industry and medicine.

EDIT:// forgot to explain the term polymer - A long chained molecule formed from thousands of monomers.

 

[danz90]

Can someone post up the correct oxidation/reduction reactions for DRY CELL and SILVER BUTTON cell

These are the one's I'm using:

DRY CELL

Oxidation: Zn(s) ---> Zn²⁺ + e^-

Reduction: MnO₂(s) + NH₄⁺ + H₂O(l) + e^- ---> Mn(OH)₃(s) + NH₃(aq)

SILVER BUTTON CELL

Oxidation: Zn(s) + 2OH^- ---> ZnO(s) + H₂O(l) + e^-

Reduction: Ag₂O(s) + H₂O(l) + e^- ---> 2Ag(s) + 2OH^-

 

[qqmore]

damnit they are so hard to remember =S


QUESTION: Discuss the need for alternative sources presently obtained from petrolchemical industry.

 

[Azreil]

EXPLAIN the term biopolymer, and identify an example.

A biopolymer is a polymer that is created from a monomer of natural origins. For example, poly(3-hydroxy-butanoate) is a biopolymer formed from the monomer 3-hydroxy-butanoate, created by the bacteria alcalignes eutrophus. [insert diagram of polymer's structure--(OCH3-CH2-CO)n]. This biopolymer is similar to the synthetic polymer nylon as it is fireproof, hardwearing, soft and able to hold dye, however is also biodegradable and renewable.

Describe the structure of a membrane filter and evaluate it's effectiveness at sanitising water.

 

[JasonNg1025]

Reduction: MnO2(s) + NH4+ + H2O(l) + e- ---> Mn(OH)3(s) + NH3(aq)

I have

2NH₄⁺ + 2e^- --> 2NH₃ + H₂

2MnO₂ + H₂ --> Mn₂O₃ + H₂O

And so

2MnO₂ + 2NH₄⁺ + 2e^- --> 2NH₃ + Mn₂O₃ + H₂O

Hmm they look different...

 

[JasonNg1025]

Describe the structure of a membrane filter and evaluate it's effectiveness at sanitising water.

A membrane filter consists of polymer sheets folded or wound around a central core. This is inside a sealed container. Water is pumped into the container until the water pressure forces the water through the polymer sheets (filters) into the central core where it flows out as clean water, leaving undissolved and even dissolved solids behind.

It is effective in sanitising water as the polymer pores are much smaller than current filters. There are 3 levels of filtration - microfiltration, filtering up to 200nm in diameter, ultrafiltration, filtering up to 100nm in diameter and nanofiltration, which has pore size 1nm. Nanofiltration can even filter ions with the right coating. This can allow for much cleaner drinking water. However, these filters are very expensive. They also require constant maintenance as pores can clog and must be regularly washed

 

[Tha Wishkah]

Chemists have solutions.

amidoinitrite

 

[danz90]

EXPLAIN the term biopolymer, and identify an example.

A biopolymer is a polymer that is created from a monomer of natural origins. For example, poly(3-hydroxy-butanoate) is a biopolymer formed from the monomer 3-hydroxy-butanoate, created by the bacteria alcalignes eutrophus. [insert diagram of polymer's structure--(OCH3-CH2-CO)n]. This biopolymer is similar to the synthetic polymer nylon as it is fireproof, hardwearing, soft and able to hold dye, however is also biodegradable and renewable.

Describe the structure of a membrane filter and evaluate it's effectiveness at sanitising water.

A membrane filter usually is comrpised of a thin-polymer (such as teflon, perhaps) which has microscopic pores, which range from diameters such as 0.001 microns to 0.1 microns. These microscopic pores trap particles such as bacteria, turbidity etc. Membrane filters used in micro and nanofiltration are quite effective at sanitising water, as they can remove almost ALL bacteria from the water supply, as well as fungi and parasites. However, more advanced filters and smaller pore sizes would be required to trap viruses. Hence, membrane filters are very effective at sanitising water, only if very small pore-sizes are used to trap ALL pathogens.

State the preferred IUPAC name of the following haloalkane:

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