HSC Chemistry Question Thread

[bethjomay]

If a question doesn't ask specifically for a diagram, but you have to explain something, can we do that via a diagram and still get the marks? 

[jakesilove]

If a question doesn't ask specifically for a diagram, but you have to explain something, can we do that via a diagram and still get the marks?

For sure, although my recommendation is to draw the diagram AND give a brief explanation, to be 100% sure you get all the marks. Better to be safe than sorry!

[jakesilove]

Do we have to draw all diagrams in pencil? I am worried that it will not scan well

Pencil scans fine, and if they tell you to draw diagrams in pencil, then you probably should. All I can say is that I didn't even bring pencils into my Science exams

[RuiAce]

Do we have to draw all diagrams in pencil? I am worried that it will not scan well

In science, this is what you're meant to do, as per front page of the exam. And tbh I reckon the scanning for the science papers was 10x better than that for math papers. (This is coming from someone who BOUGHT his exam responses.)

If a question doesn't ask specifically for a diagram, but you have to explain something, can we do that via a diagram and still get the marks? 

I for one do. I drew out my Gratzell cell and the structure of a soap last year in my exam.

Also, haha so many chemistree puns

[nibblez16]

Hello, I need help with determining the concentration of hcl... Can you please explain with displaying the formulas ur using too. Thank You

[sl.sarlak]

Hi I was wondering how do you know a chemistry question is a limiting reagent question? (Sorry if it's a stupid question)
thanks 

[jakesilove]

Hello, I need help with determining the concentration of hcl... Can you please explain with displaying the formulas ur using too. Thank You

We start off by figuring out how many moles of the Sodium Carbonate solution we have in the 25mL





Okay, now we need the chemical reaction between HCl and Sodium carbonate



Clearly, there is a 2:1 ratio. So, for every 1 mole of Sodium carbonate we have, we need 2 moles of HCl to neutralise. Therefore, if we have 0.0025 moles of Sodium carbonate, the amount of acid we must have added is 0.05 moles.

Now, we can figure out concentration by

[jakesilove]

Hi I was wondering how do you know a chemistry question is a limiting reagent question? (Sorry if it's a stupid question)
thanks 

Basically, if you ever have two chemicals being added together, and have no idea what's going on, it's going to be a limiting reagent question

[bethjomay]

Are there any specific buffer systems we need to know or can we just choose one and memorise it, bc I only have one at the moment?

[wesadora]

Basically, if you ever have two chemicals being added together, and have no idea what's going on, it's going to be a limiting reagent question

HAHAHAHAHAHAHA THIS.

[RuiAce]

Are there any specific buffer systems we need to know or can we just choose one and memorise it, bc I only have one at the moment?

Pick one and memorise it, cause otherwise they give you the buffer and its equation

[jakesilove]

Are there any specific buffer systems we need to know or can we just choose one and memorise it, bc I only have one at the moment?

Yep, just choose one and run with it!

[bethjomay]

Pick one and memorise it, cause otherwise they give you the buffer and its equation

Awesome, thank you! 

[nibblez16]

We start off by figuring out how many moles of the Sodium Carbonate solution we have in the 25mL





Okay, now we need the chemical reaction between HCl and Sodium carbonate



Clearly, there is a 2:1 ratio. So, for every 1 mole of Sodium carbonate we have, we need 2 moles of HCl to neutralise. Therefore, if we have 0.0025 moles of Sodium carbonate, the amount of acid we must have added is 0.05 moles.

Now, we can figure out concentration by

Thank You so much! Makes much more sense

[wesadora]

Hey Jake...what was Galvani's actual contribution to our understanding of electron transfer reactions? I mean, he did the whole 'animal electricity' thing but he was wrong. How would you justify his significance in the grand scheme of things....maybe just like, paved the way for the other scientists like Volta, but what more can you say? o.O bit of a vague guy lmao