Rod's Chemistry 3/4 Questions Thread

[Rod]

Hey guys,

can someone please clear up my redox terms;

Oxidation: Loss of electrons

Reduction: Gain of electrons

Oxidised: Has lost electrons

Reduced: Has gained electrons

Oxidant: Gains electrons from another substance and increases oxidation number of previous substance

Reductant: Loses electrons from another substances and reduces oxidation number

Thanks

[Rod]

Oxidation - loss of electrons

Oxidised - compound that undergoes oxidation and loses electrons

Reductant - compound that loses electrons

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Reduction - gain of electrons

Reduced - compound that undergoes reduction and gains electrons

Oxidant - compound that gains electrons

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I think I've got it now. Got so confused argh.

[Yacoubb]

All the above is correct Rod.

[Rod]

Need some help here;

So bonds that hold the tertiary structure of a protein are covalent bonds, hydrogen bonds, ion-dipole forces and dispersion forces. Why are covalent bonds apparently the 'most important' bond that makes the tertiary structure?

Thanks

[lzxnl]

Covalent bonds, the strongest attractions in a protein, make up the primary structure. Without a primary structure, any discussion of tertiary structure is moot.

[Rod]

Covalent bonds, the strongest attractions in a protein, make up the primary structure. Without a primary structure, any discussion of tertiary structure is moot.

Thanks heaps man

[Rod]

Covalent bonds, the strongest attractions in a protein, make up the primary structure. Without a primary structure, any discussion of tertiary structure is moot.

Also another question;
I've been getting the starch vs cellulose to make bio ethanol questions wrong.

This is what I know;

In order to make bio ethanol (a biofuel) you need to start off with some simple sugars and then convert it to ethanol (can be done via fermentation). These simple sugars can be broken down from starch and cellulose.

Differences between is obviously starch would be easier to break down as plants use starch as storage, and would break starch down to get glucose for energy. On the other hand cellulose is used as structure by plants, so it would be harder to break down to simple sugars for ethanol production.

Apparently in refineries, all they have to do is add amylase to starch to break it down to glucose, then it can be used for fermentation to make ethanol. Cellulose is apparently much more complex. When cellulose is broken down, other sugar molecules excluding glucose are produced, they are harder to covert to ethanol and so makes the process slower and inefficient.

So obviously, due to efficiency and time starch would be better to use.

Could you please add any other information that I have missed? I've gotten three questions related to this stuff wrong.

Thanks

[Rod]

Can anyone confirm the stuff I wrote above? ^^

Another question:

Apparently dilute sulphuric acid and magnesium oxide reaction is as follows;

Mgo + 2h+ -> mg2+ + h20

don't really get it, help appreciated,

Rod

[Rishi97]

Can anyone confirm the stuff I wrote above? ^^

Another question:

Apparently dilute sulphuric acid and magnesium oxide reaction is as follows;

Mgo + 2h+ -> mg2+ + h20

don't really get it, help appreciated,

Rod

Is this got to do with redox? If yes, this is the half equation. Give me more detail and I'll try to help you.

[nhmn0301]

Can anyone confirm the stuff I wrote above? ^^

Another question:

Apparently dilute sulphuric acid and magnesium oxide reaction is as follows;

Mgo + 2h+ -> mg2+ + h20

don't really get it, help appreciated,

Rod

MgO is basic oxide. Hence, it is able to dissociate in water and form OH-, OH- + H+ -> H20. Correct me if I'm wrong.

[lzxnl]

The oxide ion is a ridiculously powerful base; the pKa of its conjugate acid, hydroxide ion, is like 36 or something.
So oxide is protonated once to form hydroxide, which is itself still a strong base, so that reacts with more acid.

[Rod]

Me needs some help pls

A haemoglobin has four iron atoms. When analysed, the haemoglobin has 0.33% of iron by mass. What is the molecular mass of a haemoglobin molecule?

Thanks

[lzxnl]

Let's consider one mole of haemoglobin. There are four iron atoms, which means 55.8*4 = 223.2 g accounted for. This is 0.33% of the molecule's mass, so 100% of the molecule's mass is how much?

[Rod]

Let's consider one mole of haemoglobin. There are four iron atoms, which means 55.8*4 = 223.2 g accounted for. This is 0.33% of the molecule's mass, so 100% of the molecule's mass is how much?

So it would be 223.2 x 303

=67636 g ......... I got up to here and was stuck :\. How is this even possible..


Another question Nliu!

What is the exact point of rinsing the burette and pipette with the solutions which they will deliver? And also rinse the volumetric flask and with distilled water?

Thanks again

[lzxnl]

So it would be 223.2 x 303

=67636 g ......... I got up to here and was stuck :\. How is this even possible..


Another question Nliu!

What is the exact point of rinsing the burette and pipette with the solutions which they will deliver? And also rinse the volumetric flask and with distilled water?

Thanks again

Firstly you need to rinse them with water to clean the burette and pipette. Then, as there's water of a lower solute concentration than your solution, if you just immediately use that burette or pipette, you'll find that your burette or pipette solution delivered will be slightly diluted by this water.

You rinse all equipment with water to ensure their hygiene. Volumetric flasks, however, are going to have water added to them anyway; it doesn't matter if you rinse them with more water.