HSC Chemistry Question Thread

[3.14159265359]

hey for industrial, how many natural replacements should you know?

[beeangkah]

OPTION TOPIC: SHIPWRECKS

Hey, does anyone know which equation needs to be memorised for the sulphate-reducing bacteria?
Is it reduction of sulphate in water or sulphate reacting with H⁺ ions?

Thanks!

[KT Nyunt]

hey for industrial, how many natural replacements should you know?

pretty much only one in a lot of depth...
You wanna know:
- An exhaustible natural resource, what it is used for and why is it running out (think of increasing demand due to increasing populations etc.)
- A synthetic material produced industrially to replace this resource
- any relevant equations for how its produced and/or a good description of the industrial process
- any further research and progress being made

[3.14159265359]

pretty much only one in a lot of depth...
You wanna know:
- An exhaustible natural resource, what it is used for and why is it running out (think of increasing demand due to increasing populations etc.)
- A synthetic material produced industrially to replace this resource
- any relevant equations for how its produced and/or a good description of the industrial process
- any further research and progress being made

I just saw this, thank you so much!

[bhavs1]

Question regarding Industrial Chem:
Is ammonia considered a raw material for the Solvay Process? Reading from two textbooks with one saying yes,the other saying "sometimes, depending on the situation"

Hi perhaps you don't need this anymore but a raw material is a necessary reagent, as such ammonia is a raw material. However, it should also be noted that it is theoretically recycled so it isn't replenished as often and perhaps that's why textbooks may not be clear??

[Dragomistress]

Hey,
During saponification, why do we use water, oil, sodium hydroxide and ethanol? What is the point of ethanol in the process?

[3.14159265359]

Hey,
During saponification, why do we use water, oil, sodium hydroxide and ethanol? What is the point of ethanol in the process?

hey I might be wrong. but we don't need ethanol. we need sodium hydroxide, fat/oil (ester--> which is a combination of an alcohol and alkanoic acid), and excess sodium chloride (brine). maybe the ethanol issued to make the ester?

[jazcstuart]

OPTION TOPIC: SHIPWRECKS

Hey, does anyone know which equation needs to be memorised for the sulphate-reducing bacteria?
Is it reduction of sulphate in water or sulphate reacting with H⁺ ions?

Thanks!

Just going to quote this again because I would also like to know the answer, anyone know? 

[3.14159265359]

Just going to quote this again because I would also like to know the answer, anyone know? 

sorry I dont do shipwrecks as my option, otherwise I wouldve helped!

[dermite]

hi!
i'd like some help on the following qn: (Industrial Chem)

Progress in chemical engineering has been driven by improved outcomes for society and the environment.

Assess this statement with reference to the production methods of sodium hydroxide and surfactants.

(8 Marks)

[Mate2425]

Hi guys which types of detergent; anionic, cationic or non-ionic detergents lather in hard water?

Thank you.

[jazcstuart]

Hi guys which types of detergent; anionic, cationic or non-ionic detergents lather in hard water?

Thank you.

Hi, I'm guessing this is from Industrial chem, I don't actually do this option topic but I was curious (it kind of relates to chem monitoring and management, plus I like chemistry!).
I would imagine that anionic soaps don't lather because the anions are attracted to the Ca and Mg cations in hard water. Not sure about non-ionic detergents.
Have a look in the notes section (https://atarnotes.com/notes/?state=3719), you should be able to find a summary!

[aadharmg]

Hi guys which types of detergent; anionic, cationic or non-ionic detergents lather in hard water?

Thank you.

Anionic detergents (other than alkyl sulfates and alkyl phosphates) DO lather in hard water. In case of soaps, the fatty acid anions combine with those cations of hard water to precipitate and form the insoluble scum. The fact that anionic detergents lather is one of the reasons they were made, as a response to the problem with soaps.

[Dragomistress]

Hey,
How do I know if a salt is acidic or basic?

[jazcstuart]

Hey,
How do I know if a salt is acidic or basic?

One way to tell is to figure out which acid/base neutralisation reaction it comes from, for example NaCl is formed in the reaction between HCl and NaOH, NaCH₃OO from NaOH and CH₃OOH etc. The acidity/basicity of the salt depend o the strength of the acid and base:

• a strong acid and strong base form a neutral salt
• a weak acid and weak base of equal strength form a neutral salt
• a strong acid and weak base form a slightly acidic salt
• a weak acid and strong base form a slightly basic salt

However if you are asked to show whether a salt is acidic or basic, you have to split it into its ions and show whether it reacts with water (I then just use the above method to check). For example using NaCH₃OO again:
Na⁺ + H₂O ---> No reaction
CH₃OO^- + H₂O <---> CH₃OOH +OH^-
This produces OH^- ions which make the salt solution basic.

It's not too hard, you may just need to practice a few times working out whether the ions in the salt would react with water. Hope this makes sense, feel free to ask if it doesn't and I'll see if I can explain