Question Chain Thread !!! (2 Viewers)

[yorkstanham]

Question, forgot to put it with my answer.

Analyse the relationship between the position of elements in the Periodic table, and the acid-base behaviour of their oxides. (4 marks)<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

[danz90]

Question, forgot to put it with my answer.

Analyse the relationship between the position of elements in the Periodic table, and the acid-base behaviour of their oxides. (4 marks)fficeffice" /><O></O>

Far Out i just wrote a long answer to this, and then my freakin internet connection failed for some reason. Axe that.. I'm not writing it up again. LOL

Next: A sample of water contains Ca²⁺ and Mg²⁺ at the following concentrations:

[Ca²⁺] : 2.5 x 10^-4 mol.L^-1
[Mg²⁺] : 1.0 x 10^-4 mol.L^-1

Determine the hardness of the water sample in ppm.

M(CaCO₃) = 100 g.mol^-1

 

[yorkstanham]

Next: A sample of water contains Ca²⁺ and Mg²⁺ at the following concentrations:

[Ca²⁺] : 2.5 x 10^-4 mol.L^-1
[Mg²⁺] : 1.0 x 10^-4 mol.L^-1

Determine the hardness of the water sample in ppm.

M(CaCO₃) = 100 g.mol^-1

35 ppm?

 

[starf1sh]

Commercial radioisotopes are produced in nuclear reactors as well as particle accelerators.
Example: Technetium-99m is a commercial radioisotope widely used in medicine for diagnostic imaging purposes.
Molybdenum-98 is bombarded with a neutron in a nuclear reactor, to produce Molybdenum-99.
Molybdenum-99 then undergoes Beta-decay to form Technetium-99m. ( ^99m₄₃ Tc )

Transuranic elements are those which have an atomic number > 92. (ie after Uranium). These elements are usually produced in heavy ion particle accelerators. Eg. Darmstadtium-269 is produced when a Nickel-62 ion is accelearted in a particle acceleator (with the combination of electrical and magnetic fields to generatic kinetic energy) , and is bombarded into a Lead-208 ion. The nuclei of the two ions combine to form the nucleus of a Darmstadtium-269 atom.


Question: Outline a procedure you would follow to produce a standard solution of Lead ions at a concentration of 10µg/100mL , starting with a small quantity of lead nitrate crystals.

i think the first three transuranic elements are produced in nuclear reactors?

 

[danz90]

i think the first three transuranic elements are produced in nuclear reactors?

yep, thats true.

35 ppm?

Correct


Next: Compare the chemical and physical properties of Ozone and Oxygen.

 

[Azreil]

Ozone: is a blue colour, highly toxic, unstable, highly soluble, boils at a higher temperature and is a stronger oxidant.
Oxygen: is colourless, non-toxic, highly stable, generally insoluble, boils at a lower temperature and is a stronger oxidant.

Ozone forms with a co-ordinate covalent bond which is far less stable than the covalent bond both it and oxygen possess. The higher mass gives it the higher boiling point.


Explain how a buffer system works, with reference to a natural buffer system.

 

[yorkstanham]

Next: Compare the chemical and physical properties of Ozone and Oxygen.

Chemical: Ozone is far more reactive than oxygen as it is polar due to the single coordinate covalent bond which creates an uneven balance around the central atom, where as oxygen is non-polar and contains a double covalent bond. This leads ozone to being less stable than oxygen.

Ozone also has a higher solubility due to it being once again polar. Since 'like-dissolves-like' ozone readily dissolves. Oxygen however is non-polar and hence its solubility (14.6mg/L) is significantly lower than that of ozone (1050mg/L)

Physical: Ozone has both a higher melting (-193) and boiling point (-111) than that of oxygen (-219 and -183). This is due to ozone having a higher molecular mass and hence stronger dispersion forces between molecules than that of ozone. Ozone is also muchc more denser than oxygen, (2.144gL compared to 1.429g/L), this is due to the stronger intermolecular force present in the polar ozone when compared to the non-polar oxygen.


NEXT QUESTION: Describe and explain evidence for the need to monitor levels of lead ions in society.

 

[danz90]

Ozone: is a blue colour, highly toxic, unstable, highly soluble, boils at a higher temperature and is a stronger oxidant.
Oxygen: is colourless, non-toxic, highly stable, generally insoluble, boils at a lower temperature and is a stronger oxidant.

Ozone forms with a co-ordinate covalent bond which is far less stable than the covalent bond both it and oxygen possess. The higher mass gives it the higher boiling point.


Explain how a buffer system works, with reference to a natural buffer system.

A buffer system resists drastic changes to pH, when a small amount of acid or base are added. It consists of equal amounts of an acid (or base), and its conjugate base (or conjugate acid). Since both conjugates are present, by adding H⁺ and OH^-, both can be 'buffered' by the system.

A natural buffer system exists in the blood, CO₂/H₂CO₃/H⁺ + HCO₃^-

If there is excess H⁺ in the blood (acidosis), the equilibrium will shift in such a manner to remove SOME of the excess H⁺.
The following reactions will be favoured (since there is an increase in [H⁺]
H⁺ + HCO₃^- ---> H₂CO₃(aq)
H₂CO₃(aq) ---> H₂O(l) + CO₂(aq)
CO₂(aq) ---> CO₂(g)

Hence, there will be an increase in the breathing rate, to buffer the excess H⁺, in order to maintain optimal enzyme functioning.

Next: Using an example, account for the change in the oxidation state of a species in terms of loss or gain of electrons?

 

[yorkstanham]

Explain how a buffer system works, with reference to a natural buffer system.

A buffer is a system composed of a weak base and its conjugate acid or a weak acid and its conjugate base. A buffer controls the alkalinity/aciditity of a solution and resists changes of pH with the addition of small amounts of acid or base.

A natural buffer system is the H2CO3/HCO3- buffer present in human blood. This buffer is responsible for the maintaining the blood pH level between 7.35 and 7.45, fluctuations out of this range can be life threatening. When acidosis occurs the equilibrium readjusts to minimise the change:

HCO3- + H+ --> H2CO3

When alkalosis occcurs the buffer once again minimises the change ensuring the health of the individual:

H2CO3 + OH- --> HCO3- + H2O

Next Q: Explain the differences in boiling and melting points between straight chained alkanoic acids, alkanols and alkanes.

 

[adnan91]

Chemical: Ozone is far more reactive than oxygen as it is polar due to the single coordinate covalent bond which creates an uneven balance around the central atom, where as oxygen is non-polar and contains a double covalent bond. This leads ozone to being less stable than oxygen.

Ozone also has a higher solubility due to it being once again polar. Since 'like-dissolves-like' ozone readily dissolves. Oxygen however is non-polar and hence its solubility (14.6mg/L) is significantly lower than that of ozone (1050mg/L)

Physical: Ozone has both a higher melting (-193) and boiling point (-111) than that of oxygen (-219 and -183). This is due to ozone having a higher molecular mass and hence stronger dispersion forces between molecules than that of ozone. Ozone is also muchc more denser than oxygen, (2.144gL compared to 1.429g/L), this is due to the stronger intermolecular force present in the polar ozone when compared to the non-polar oxygen.


NEXT QUESTION: Describe and explain evidence for the need to monitor levels of lead ions in society.

\



Lead must be monitored in society. It is a neurotoxin that causes severe mental retardation and affects the bofies nervous system. Lead was commonly used in household paints and fuel additives thus when housholds were demolished lead may have been passed onto our waterways throught the soil. Previous to the discovery of the AAS for example Lead ions had were not found in small amounts. Today using the AAS lead ion concentrations can be measured and thus if levels are out of bounds actions can be taken out quickly to avoid any damage to life.


This is more for the industrial chem ppl: If they ask you to model the steps in the solvay tower. Can we choose any reaction. Say for example. Recovery of ammonia and CaCO3 kiln CO2 production and NaHCO3 turning into NaCO3. Btw this was a practical

 

[SkimDawg]

Explain how a buffer system works, with reference to a natural buffer system.

going through piles of notes here..
A buffer solution is a solution that contains comparable amounts of a weak acid and its conjugate base and which is therefore able to maintain an approximately constant pH even when significant amounts of strong acid or strong base are added to it.
In rain water this equilibrium produces pH of about 5.7 to 6. In rivers or lokaes where some HCO(3)- comes from dissolving salts out of the rocks around the rivers and lakes, this added HCO(3)- pushes the equilibrim below to the left and so raises pH to between 6.5 and 7.5
H2CO3 + H2O <----> H3O+ + HCO3-
To be a buffer solution there must be comparable amounts of H2CO3 and HCO3- in the solution and this means that there must be a source of HCO3- apart from the dissolved CO2. Hence lakes and rivers are only buffered if there are carbonate rocks available from which HCO3- can be formed.

 

[yorkstanham]

This is more for the industrial chem ppl: If they ask you to model the steps in the solvay tower. Can we choose any reaction. Say for example. Recovery of ammonia and CaCO3 kiln CO2 production and NaHCO3 turning into NaCO3. Btw this was a practical

Yeah pretty sure we can, we did both the carbonation with ammonia and the carbonating tower using dry ice

 

[adnan91]

Yeah pretty sure we can, we did both the carbonation with ammonia and the carbonating tower using dry ice

Can you explain them too me plz i just wanna compare. Because u know how some steps have more than one reaction going on. And im not too sure if we can just model ONE reaction not the whole thing

 

[danz90]

A buffer is a system composed of a weak base and its conjugate acid or a weak acid and its conjugate base. A buffer controls the alkalinity/aciditity of a solution and resists changes of pH with the addition of small amounts of acid or base.

A natural buffer system is the H2CO3/HCO3- buffer present in human blood. This buffer is responsible for the maintaining the blood pH level between 7.35 and 7.45, fluctuations out of this range can be life threatening. When acidosis occurs the equilibrium readjusts to minimise the change:

HCO3- + H+ --> H2CO3

When alkalosis occcurs the buffer once again minimises the change ensuring the health of the individual:

H2CO3 + OH- --> HCO3- + H2O

Next Q: Explain the differences in boiling and melting points between straight chained alkanoic acids, alkanols and alkanes.

Straight-chained alkanoic acids and alkanols have higher boiling and melting points than alkanes, since they have polar functional groups (such as -OH and C=O and COOH). As a result, these polar functional groups, molecules of alkanoic acids and alkanols are joined by intermolecular forces such as hydrogen bonding, permanent dipole-dipole forces, while molecules of alkanes are bonded simply by weaker dispersion forces. Hence, greater energy is required to break (for boiling pt) or weaken(for melting pt) intermolecular forces between molecules of alkanoic acids, and alkanols, in comparison to alkanes. Therefore, alkanoic acids and alkanols have higher bpts and mpts than alkanes.

Alkanoic acids contain an extra polar C=O (carbonyl) bond within their molecules, in addition to a polar hydroxy group, which is present in alkanols. As a result, alkanoic acids are slightly more polar than alkanols, thus leading to stronger permanent dipole-diple forces, and more extensive hydrogen bonding between molecules of alkanoic acids, than the intermolecular forces in alkanols. Hence, greater energy is required to weaken and break intermolecular forces in alkanoic acids, than in alkanols, hence the higher boiling and melting points in alkanoic acids, than alkanols.

Describe the recent discovery of a named transuranic element.

 

[johnnydepp]

Assess the impact of the process of polymerisation on the environment and society.
this one's a toughie

 

[yorkstanham]

Next: Using an example, account for the change in the oxidation state of a species in terms of loss or gain of electrons?

Cu + H<SUB>2</SUB>SO<SUB>4 </SUB>* CuSO<SUB>4</SUB> + SO<SUB>2</SUB> + H<SUB>2</SUB>O
Initially copper's oxidation state is 0, since it is an element. However once reacted with concentrated sulfuric acid it has been reduced and hence the oxidation state has changed from 0 to 2.

 

[danz90]

Can you explain them too me plz i just wanna compare. Because u know how some steps have more than one reaction going on. And im not too sure if we can just model ONE reaction not the whole thing

we modelled the step where ammoniacal brine is carbonated, producing NaHCO₃.

As a source of CO₂, we just had a conical flask with marble chips, added HCl, which then released CO₂(g). This was attached to a delivery tube, which bubbled CO₂(g) into the ammoniacal brine. This modelled that particular step in the solvay process.

We then placed the carbonated ammoniacal brine into the fridge for a few hours. After that, we saw a thin layer of white precipitate at the bottom of the brine solution. We carefully decanted the liquid, leaving the white solid at the bottom. We poured a few drops of HCl over the solid, and observed bubbling. THis confirmed that NaHCO₃ was produced.

 

[danz90]

Assess the impact of the process of polymerisation on the environment and society.
this one's a toughie

who can be f'ed writing another long response. lol

 

[johnnydepp]

who can be f'ed writing another long response. lol

dot points will do

 

[SkimDawg]

Here's one for fun. Identify this molecule, and its effects on society (hint: 60's). Sorry couldnt make it smaller lol.