Chemistry Pop-Quiz

Shox

Paschen series, is dat on the course??

JC 2K3

Yes.

What does edta stand for?

alancork

ethylene diamine tetra-acetic acid..

Q. What's the difference between the Greenhouse Effect and the Enhanced Greenhouse Effect ( thats on the option...)

Your Man

ethylene diamine tetracetic acid? or somthing like that.

Describe how iron tablets are made into solution in the iron tablet experiment and give a reason as to why they are dissolved in H2SO4?

madnirvana

ethelenediamenetetraacetic acid

madnirvana

Your Man wrote:

ethylene diamine tetracetic acid? or somthing like that.

Describe how iron tablets are made into solution in the iron tablet experiment and give a reason as to why they are dissolved in H2SO4?

crush the tablets with mortar and pestle, Add few drops of H2So4

it adds H+ ions. prevents hydrolosys

JC 2K3

alancork wrote:

ethylene diamine tetra-acetic acid..

Q. What's the difference between the Greenhouse Effect and the Enhanced Greenhouse Effect ( thats on the option...)

You pay extra for the latter.

(I dunno, I don't do the option )

nedward

alancork wrote:

ethylene diamine tetra-acetic acid..

Q. What's the difference between the Greenhouse Effect and the Enhanced Greenhouse Effect ( thats on the option...)

The greenhouse effect is the trapping of the Sun's heat in the atmosphere.

The enhanced effect is the more than usual heat being trapped due to increased amounts of greenhouse gases in the air because of human activities.


How would you go about converting ethanoic acid to ethanal, and thence to ethanol?

Lucas10101

Reflux & Distillation for the forward one Ethanol, Ethanal and Ethanoic Acid.
Not sure about the reversed one.

Q. What's the difference between the Haber and Contact Process and under what conditions do each normally suffice at and what's formed in each process?

Your Man

Haber process is the manufacture of ammonia, ideal conditions are high pressure and low temperature but a temp of 200 atmospheres is used as HP is too costly, a high temp is used to bring the reaction to equilibruim faster.
Contact Process: the industrial production of sulphuric acid, high pressure is ideal but too costly, also a low temp is ideal but a temp of 450 degrees is used.

Distinguish between intramolecular bonding and intermolecular bonding.

JC 2K3

Intramolecular - Bonding between atoms in molecules.
Intermolecular - Bonding between molecules in substances.

Lucas10101

Distinguish between:

(i) Van Der Waals Forces
(ii) Dipole-Dipole Forces
(iii) Hydrogen Bonding

What is a dipole, how do these affect Boiling Points, if at all?

Shox

Van der waals forces: only between non polar molecules

Dipole dipole forces : Only between polar molecules

Hydrogen bonding: Type of dipole dipole force, when a hydrogen atom is bonded to a small electronegative atom of oxygen, fluorine or nitrogen


A 25cm(cubed) sample of a 2M hydrochloric acid solution is diluted to 2 lites with water. Calculate the concentration of the resulting solution?
(took this from the papers, my stoichiometry sucks)???

madnirvana

Shox wrote:

Van der waals forces: only between non polar molecules

Dipole dipole forces : Only between polar molecules

Hydrogen bonding: Type of dipole dipole force, when a hydrogen atom is bonded to a small electronegative atom of oxygen, fluorine or nitrogen


A 25cm(cubed) sample of a 2M hydrochloric acid solution is diluted to 2 lites with water. Calculate the concentration of the resulting solution?
(took this from the papers, my stoichiometry sucks)???

im not studying stoichiometry ATALL its the worst chap..:mad:


diference between ethanal and ethanoic acid?

JC 2K3

Shox wrote:

A 25cm(cubed) sample of a 2M hydrochloric acid solution is diluted to 2 lites with water. Calculate the concentration of the resulting solution?
(took this from the papers, my stoichiometry sucks)???

Lol, stoichiometry's píss, in this instance, volume is indirectly proportional to molarity.

2000/25 = 80
2/80 = 1/40 = 0.0025M

Simple

madnirvana wrote:

diference between ethanal and ethanoic acid?

Ethanal = CH3CHO
Ethanoic Acid = CH3COOH

So that means Ethanal is a methyl group bonded to a carbonyl group and Ethanoic Acid is a methyl group bonded to a carboxyl group, right?

What is the Electrochemical Series?

genericgoon

A series which arranges metals in terms of their reactivity

Expalin the electron pair repulsion theory.

bebop!

Valence Shell Electron Pair Repulsion Theory. (VSEPR)

This theory states that the shape of a molecule depends on the number of pairs of electrons in the outer shell of the atom.

The pair of electrons that are not involved in a covalent bond are called a lone pair. The total number of electron pairs around the atom of the molecule determines the shape of the molecule, since elctrons are negatively charged, pairs of electrons will repel each other and arrange themselves so that are as far apart as possible from each other.

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Q. In the experiment to produce ethyne gas, Liquid X is dropped onto solid Y to produce ethyne gas.

Name X and Y.

Lucas10101

Water = X
Calcium Carbide = Y

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Q. Name three impurities that normally exist in Calcium Carbide and how these could be removed? Give one use of Ethyne Gas?

Ethyne has three bonds in the C2H2, and is extremely unsaturated. Benzene C6H6 has many double bonds which also should make it unsaturated but is found to be very unreactive. Both are soluble in Cyclohexane but are insoluble in water. C2H2 makes Bromine colourless.

(i) Distinguish between Saturation and Unsaturation?
(ii) Why is Benzene so reactive if it has conditions for unsaturation?
(iii) How is Benzene normally represented as drawn?
(iv) Why are they insoluble in water?
(v) Why does Bromine go colourless and what's this a test for?
(vi) Would Iodine dissolve Methylbenzene? Give the property of Iodine that justifies your answer? Name a suitable substance that gives the opposite result to that obtained in part 1 of question (vi).

madnirvana

Q. Name three impurities that normally exist in Calcium Carbide and how these could be removed? Give one use of Ethyne Gas?

calcium Sulfide, Calcium phosphide, calcium nitride..
removed by bubbling through soln of copper sulfate .


Use = welding and cutting

Ethyne has three bonds in the C2H2, and is extremely unsaturated. Benzene C6H6 has many double bonds which also should make it unsaturated but is found to be very unreactive. Both are soluble in Cyclohexane but are insoluble in water. C2H2 makes Bromine colourless.

(i) Distinguish between Saturation and Unsaturation?
if turns bromine water yellowish red turns colourless +> its unsaturated.
forms a soln dibromeothanol


(ii) Why is Benzene so reactive if it has conditions for unsaturation?
because of electron clowds and pi bonds..
i am not very sure with this one.


(iii) How is Benzene normally represented as drawn?
circle in a hexagon

(iv) Why are they insoluble in water?
hydrogen bonding


(v) Why does Bromine go colourless and what's this a test for?
unsaturation.....


(vi) Would Iodine dissolve Methylbenzene?
yes/// both non polar ?


Give the property of Iodine that justifies your answer?
non polar?


Name a suitable substance that gives the opposite result to that obtained in part 1 of question
i dunnoconfused:

Lucas10101

Electronegativity is defined as the relative attraction that the shared pair of electron have for the covalent bonds in an atom. Atomic Radius is defined as half the distance between two nuclei of atoms that are joined by a single covalent Bond. Ionisation Energy is the defined as the energy to remove the most loosely bound electron from a neutral gaseous atom.

Q.
(i) What unit is Ionisation Energy measured in?
(ii) Account for the changes in Atomic Radii going across a period?
(iii) Account for for the changes in Electromegativity values going down a group?
(iv) Going down a group, account for the Reactivity of Group 1 in the Periodic Table?

( 30 Marks LCH Sample Paper)

remus808

I don't think I could answer more than one or two of the questions in this whole thread.

How screwed am I?

nedward

Lucas10101 wrote:

Q.
(i) What unit is Ionisation Energy measured in?
(ii) Account for the changes in Atomic Radii going across a period?
(iii) Account for for the changes in Electromegativity values going down a group?
(iv) Going down a group, account for the Reactivity of Group 1 in the Periodic Table?

( 30 Marks LCH Sample Paper)

i. kJ mol^-1
ii. Atomic radii increase due to an increase in nuclear charge, and no increase in the screening effect of inner electrons.
iii. Electronegativity decreases due to new shells being created, leading to increased atomic radius, and the screening effect of inner electrons.
iv. These elements are reactive due to the stability of the noble gas configuration of their ions. This makes them reactive, as they want to lose their outer electrons. Reactivity increases down the group, due to the screening effect and new shells being created.

I hate those types of question-so woolly.


Anyway, what reagents would youse doorty lookin doortboords use to determine the presence of sulphate ions in a solution of sulfuric acid?

Your Man

barium chloride added to a salt of either sulphate/sulfite and water, solution then turns cloudy indicating the presence of the ions.

State 5 properties of catalyts

nedward

Specific to a reaction.
Unchanged chemically by a reaction.
May speed up or slow down a reaction.
In a reversible reaction, catalyse both the forward and the backward reaction to the same extent.
Had to check the last one---small amounts needed!


Five factors affecting the rate of a chemical reaction.


EDIT Catalyst poisons, right?

bebop!

Temperature
Nature of Reactants
Concentration
Particle Size
Catalysts

Q. What is Chromatography?

nedward

bebop! wrote:

Temperature
Nature of Reactants
Concentration
Particle Size
Catalysts

Q. What is Chromatography?

It is a separation technique based on a mobile phase moving in contact with a selectively absorbent stationary phase.


What is organic synthesis?

bebop!

nedward wrote:

What is organic synthesis?

The Process of making organic compounds from simpler starting materials.


What are Oxidation Numbers?

genericgoon

nedward wrote:

ii. Atomic radii increase due to an increase in nuclear charge, and no increase in the screening effect of inner electrons.

I assume you meant decrease.

pilchard

bebop! wrote:

What are Oxidation Numbers?

The charge an atom has or appears to have in a compound.

Define activation energy?

HungryJoey

Oh great, I have to do chemistry on Tuesday with the flu :mad: I'll more then likely still have it then. How on earth did I manage to catch it and especially at this time of the year.

Hj