HSC Chemistry Question Thread

[hanaacdr]

Oxygen reacts with hydrogen explosively under high temperatures, so the ingoing gas stream must be monitored so all oxygen is removed before it enters the reaction vessel! The 1:3 ratio for N:H maximises efficiency of conversion into ammonia, because a buildup of excess gas will take up space in the vessel and also pose a risk of explosion.

THANK YOU!

[Kekemato_BAP]

Are metal hydroxides salts? I get mixed answers whenever I google it..

[arunasva]

Someone help me. Pleeze.

[Kekemato_BAP]

Someone help me. Pleeze.

Hi, do you have the full question?
This question would be done by first calculating the moles of SO2 from the data of the question, then multiplying by 24.79mol/L to get volume of gas.
It depends on the rest of the question.

[jakesilove]

Are metal hydroxides salts? I get mixed answers whenever I google it..

Hey! This is where definitions fail us; in Chemistry, it's not always helpful to lump something in under a particular definition. However, we can come to some sort of answer if we try hard enough!

A salt is just an ionic compound, containing an anion and a cation. Strictly, therefore, a metal hydroxide is NOT a salt. There is no 'anion', but rather a compound which we could call the 'anion'. So, by stretching the definition a bit, I would be more than happy to call a metal hydroxide a salt, claiming that the -OH is the anion.

The real question to ask yourself is this; is determining that a metal hydroxide is a salt helpful in any way? Definitions help us to easily describe a substance, and describing NaOH as a metal hydroxide is plenty (although a strong base would be better!).

Overall, I would say that the answer is no, but you could probably convince some chemists to the contrary.

[Wren]

Hey I was just wondering does it matter which reagent is added in excess in esterification or can it just be any?

[jakesilove]

Hey I was just wondering does it matter which reagent is added in excess in esterification or can it just be any?

I can't imagine it really matters, as the reaction won't go to completion anyway! I would just add plenty of both

[RuiAce]

Hey I was just wondering does it matter which reagent is added in excess in esterification or can it just be any?

I can't imagine it really matters, as the reaction won't go to completion anyway! I would just add plenty of both

Usually the alkanoic acid is added in excess.

Two reasons:
1. The excess is easy to neutralise. It's hard trying to eliminate excess alkanol
2. Only one is added in excess to force the equilibrium further than otherwise. If the concentrations of both are increased then the effect of LCP isn't as significant.

[Wren]

Usually the alkanoic acid is added in excess.

Two reasons:
1. The excess is easy to neutralise. It's hard trying to eliminate excess alkanol
2. Only one is added in excess to force the equilibrium further than otherwise. If the concentrations of both are increased then the effect of LCP isn't as significant.

Thanks guys

[bsdfjnlkasn]

Hey there,

I've just started chemical monitoring and management and was wondering if we were required to know the 3 steps of the Haber process?

1.   Preparing the reactants
2.   The reaction vessel
3.   Condensing the NH3 (g) to liquid ammonia, ready for distribution

We haven't covered them at school but since there is such a big focus on it, it just seemed strange that we just identified simple things to do with the reaction and the monitoring aspects of how ammonia is produced. I mean great if we don't have to because that's less to memorise but if we do, then it'd be good to know because we completely skipped over it in class.

Thank you!! 

[jakesilove]

Hey there,

I've just started chemical monitoring and management and was wondering if we were required to know the 3 steps of the Haber process?

1.   Preparing the reactants
2.   The reaction vessel
3.   Condensing the NH3 (g) to liquid ammonia, ready for distribution

We haven't covered them at school but since there is such a big focus on it, it just seemed strange that we just identified simple things to do with the reaction and the monitoring aspects of how ammonia is produced. I mean great if we don't have to because that's less to memorise but if we do, then it'd be good to know because we completely skipped over it in class.

Thank you!! 

You definitely DON'T need to know about any of those things! The curriculum focuses very specifically on certain aspects of the Haber process, but leaves out the vast majority. That's because the interesting Chemistry occurs during the actual process, rather than during the practical elements required to distribute the product. So, it's good that you have the broader picture in mind, but you don't need to know it in any great detail.

[RuiAce]

I just 'knew' that it was condensed to water for point 3 and nothing about point 1.

However there's a bit more to know about the reaction vessel
- Importance of 3:1 H:N ratio
- Effect of impurities
  - Inert impurities such as argon
  - Reactive impurities such as oxygen

There's also the delicate glassware but that's under LCP and the pressure stuff.

[beau77bro]

theres seems to be a very heavy amount of content on the actual steps of the haber process, is it essential to know all of it? conquering talks about how they remove certain products and things that might impede the reaction. but where do all these steps fit in the actual syllabus? sorry if im a bit vague but just abit unsure. thanks

[RuiAce]

theres seems to be a very heavy amount of content on the actual steps of the haber process, is it essential to know all of it? conquering talks about how they remove certain products and things that might impede the reaction. but where do all these steps fit in the actual syllabus? sorry if im a bit vague but just abit unsure. thanks

Impurities definitely matters.

The monitoring of the Haber process is certainly a part of the course. If you increase the pressure by adding impurities then all you're doing is slowing the reaction down, and you definitely need to know about this. Increasing the pressure by adding something like Argon does not shift the equilibrium any way because you're actually hindering both the forward and reverse reactions.

You also need to know that you definitely do not want any reactive impurities either like oxygen. Reactions involving oxygen are quite explosive and would potentially break the delicate glassware (which leads to a whole chain of complications you should be able to figure out yourself).

Relevant syllabus dot point as addressed on easychem

[Nicko912]

Hi quick question ( Daniell cell ),

If I were to mix Cu(NO₃)₂ solution in a single beaker with ZnSO₄ solution with a copper and zinc electrode in the single beaker, what are two predictions why the cell won't work? ( wire and load is still present )