HSC Chemistry Question Thread

[MisterNeo]

HI,
In industrial Chemistry for the head of an anionic detergent, is it sulfate or sulfanoate? and how do these look structurally?

Also for esterification my school used a bunsen burner, which I understand we should not use for safety reasons. I was just wondering when drawing a diagram for this prac, how do we draw the heating mantle? Like does it also need a water bath, and boiling chips, and a retort stand etc?
Thanks.

In most textbooks, they have sulfonate heads. Sulfates have 4 oxygen, and the alkyl chain is bonded to an oxygen instead of the sulfur. I would use the sulfonate or benzyl sulfonate in the HSC.

When drawing the esterification reflux setup:
-If drawn with Bunsen burner, must have a water bath (safety).
-If drawn with a heating mantle, doesn't need a water bath (it has a curved base).
I've always drawn it with a Bunsen + water bath. Bunsens must not be used against the glass directly in case it cracks. it's acceptable to use a water bath with Bunsens. The retort stand holds it upright in the water bath. It also needs boiling chips.

[J.B]

In most textbooks, they have sulfonate heads. Sulfates have 4 oxygen, and the alkyl chain is bonded to an oxygen instead of the sulfur. I would use the sulfonate or benzyl sulfonate in the HSC.
(Image removed from quote.)(Image removed from quote.)
When drawing the esterification reflux setup:
-If drawn with Bunsen burner, must have a water bath (safety).
-If drawn with a heating mantle, doesn't need a water bath (it has a curved base).
I've always drawn it with a Bunsen + water bath. Bunsens must not be used against the glass directly in case it cracks. it's acceptable to use a water bath with Bunsens. The retort stand holds it upright in the water bath. It also needs boiling chips.

Thank you

[Mathew587]

Thank you

you also need to draw and specify boiling chips

[Iminschool]

For Industrial Chem, does the equilibrium constant (K) have an arbitrary unit? Or is it mol/L?

[Anjally]

Hi why does the dehydration process of ethene need a catalyst?

[Savas_P]

Hi why does the dehydration process of ethene need a catalyst?

It needs a powerful acid catalyst (sulphuric acid) to break off the C-OH and C-H bonds on the ethanol molecules.

[Iminschool]

Hi why does the dehydration process of ethene need a catalyst?

Btw its the dehydration of ethanol to produce ethene.
The dehydration of ethanol is the chemical process where the water molecule is removed from the ethanol. A strong catalyst in sulfuric acid is required as the hydroxyl functional group (OH-) is bonded strongly to the (CH3CH2) chain. Therefore the sulfuric acid is used to lower the activation energy as it provides an alternative pathway for the reaction to occur.

[Natasha.97]

Hi why does the dehydration process of ethene need a catalyst?

Hi!

A catalyst (namely concentrated H₂SO₄) is used to lower the activation energy of the reaction. As the forward reaction is exothermic, the temperature cannot be too high (Le Chatelier's Principle: the reverse reaction will be favoured), otherwise the overall yield is reduced. The catalyst also acts as a 'dehydrating agent' by absorbing water (formed alongside ethene), the forward reaction will be favoured, promoting the formation of ethene.

Hope this helps

Brown: Covered in Module 2 (The Acidic Environment)

[MisterNeo]

For Industrial Chem, does the equilibrium constant (K) have an arbitrary unit? Or is it mol/L?

They don't have units because it's a ratio of products to reactants.

[Iminschool]

They don't have units because it's a ratio of products to reactants.

I thought so, for some reason Success One had mol/L in one of their solutions

[necromantic]

Hi,
in the cathode reaction for a Lead Acid Battery, the valency of Lead changes from 4+ to 2+. How/why does this happen?

[Natasha.97]

Hi,
in the cathode reaction for a Lead Acid Battery, the valency of Lead changes from 4+ to 2+. How/why does this happen?

Hi!

The total oxidation number of a compound is 0. In this case, the oxidation number of O₂ is -4 , so to balance it out, the oxidation state of Pb = +4.
In the compound PbSO₄, SO₄ has a charge of -2 (derived from the formula H₂SO₄), so the oxidation state of Pb = +2

Hope this helps

[Dragomistress]

What is the net ionic equation for
2Al(s) + 6HCL(aq) --> 3AlCl3(aq) + 3H2(g)

[Natasha.97]

What is the net ionic equation for
2Al(s) + 6HCL(aq) --> 3AlCl3(aq) + 3H2(g)

Hi!

Balanced equation: 2Al_(s) + 6HCl_(aq) → 2AlCl_3(aq) + 3H_2(g)

Next, write it out in terms of its constituent ions:
2Al_(s) + 6H⁺_(aq) + 6Cl^-_(aq) → 2Al³⁺_(aq) + 6Cl^-_(aq) + 3H_2(g)

Cancel out the spectator ions (in this case, Chlorine has not been changed). This results in:
2Al_(s) + 6H⁺_(aq) → 2Al³⁺_(aq) +3H_2(g)

Hope this helps

[mxrylyn]

Hey,

So i'm taking notes on halogenation and the addition of halogens to ethylene, and in the formula (ethylene + bromine ----> 1,2-dibromoethane) , I don't know what the "1,2" in the dibromoethane means or is referring to.