HSC 2012-2015 Chemistry Marathon (archive) (3 Viewers)

[Drsoccerball]

re: HSC Chemistry Marathon Archive

Has anyone seen any HSC questions asking about an experiment of galvanic cells?

Theres been a few

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

I got one in my chem trial, so I don't see any reason there shouldn't be one in the HSC

We had two choices and we didn't have to pick a galvanic cell...

 

[Ekman]

re: HSC Chemistry Marathon Archive

We had two choices and we didn't have to pick a galvanic cell...

What? I don't think you are talking about the same question as I am. Because the question was about testing metals, and if you didn't talk about galvanic cells, well im not sure how you would get the marks. In fact the marking criteria were talking about galvanic cells, there wasn't any choice about it...

The only choice you had to make is whether you put down a qualitative or quantitative method for the testing. (I put both in the exam, I had a little extra time)

 

[BlueGas]

re: HSC Chemistry Marathon Archive

I got one in my chem trial, so I don't see any reason there shouldn't be one in the HSC

What was the question like?

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

What? I don't think you are talking about the same question as I am. Because the question was about testing metals, and if you didn't talk about galvanic cells, well im not sure how you would get the marks. In fact the marking criteria were talking about galvanic cells, there wasn't any choice about it...

The only choice you had to make is whether you put down a qualitative or quantitative method for the testing. (I put both in the exam, I had a little extra time)

I did galvanic cell but the girl coming first in chem who got full marks used the idea of displacement reaction to determine which metals more reactive which is what you were suppose to do. (Since the question said no additional chemicals can be used)

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

What was the question like?

It gave four random metals and asked to develop a procedure to determine which one was more reactive.

 

[BlueGas]

re: HSC Chemistry Marathon Archive

It gave four random metals and asked to develop a procedure to determine which one was more reactive.

So how would you develop a procedure to answer this question?

 

[el_manu]

re: HSC Chemistry Marathon Archive

I did galvanic cell but the girl coming first in chem who got full marks used the idea of displacement reaction to determine which metals more reactive which is what you were suppose to do. (Since the question said no additional chemicals can be used)

What does that even mean?

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

So how would you develop a procedure to answer this question?

Well what i did was use a galvanic cell with the highest oxidising agent which i picked to be chlorine. Then i said connect the galvanic cell to a galvanometer and the one that produces the highest value is more reactive etc... And i lost 2 marks for not giving quantities of liquid and also because my experiment wasnt "safe" since it said in the question "outline a safe experiment...

 

[BlueGas]

re: HSC Chemistry Marathon Archive

What does that even mean?

In a metal displacement reaction, the more reactive metal will displace the less reactive metal.

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

In a metal displacement reaction, the more reactive metal will displace the less reactive metal.

What does that mean though?

 

[Librah]

re: HSC Chemistry Marathon Archive

Guys, i know you have your pride n what not, but there's no shame in using the internet that you or you local library has paid for http://lmgtfy.com/?q=displacement+reaction.

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

Guys, i know you have your pride n what not, but there's no shame in using the internet that you or you local library has paid for http://lmgtfy.com/?q=displacement+reaction.

haha. lol.
You saved me typing two words. THX!

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

Which Hydrocarbons are gases at room temperature?

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

Which Hydrocarbons are gases at room temperature?

Usually the ones with less carbons and hydrogens have a higher probability of being gases at room temperature.

 

[Ekman]

re: HSC Chemistry Marathon Archive

Which Hydrocarbons are gases at room temperature?

Id say that due to the lack of hydrogen bonding, and because of the weak dispersion forces, hydrocarbons would have lower melting a boiling points. And as drsoccerball said, smaller chain hydrocarbons are more likely to be gases, and this ties back into the point about having weaker dispersion forces, due to their lower molecular weight.

 

[Mr_Kap]

re: HSC Chemistry Marathon Archive

Id say that due to the lack of hydrogen bonding, and because of the weak dispersion forces, hydrocarbons would have lower melting a boiling points. And as drsoccerball said, smaller chain hydrocarbons are more likely to be gases, and this ties back into the point about having weaker dispersion forces, due to their lower molecular weight.

Thx.

So like C1 to C5 Hydrocarbons then?

 

[BOS Secret Service]

re: HSC Chemistry Marathon Archive

Describe the structure of cellulose, relating to its properties.

Cellulose is a condensation polymer and a biopolymer made of B-Glucose monomer units, which flip upside down every second glucose. Due to hydrogen bonding present within the molecule, cellulose is insoluble because the intermolecular forces cannot be easily broken. Because ever second glucose unit is flipped upside down, a reasonably linear molecule is produced, increasing the density and strength of the molecule.

 

[Study_like_a_nerd]

re: HSC Chemistry Marathon Archive

Does the water molecule only have hydrogen bonding intermolecular forces or does it also have dipole dipole forces - some websites say it does and some say it doesn't so I'm a bit confused. I originally though water doesnt have dipole dipole forces because its a symmetrical molecule...

 

[Drsoccerball]

re: HSC Chemistry Marathon Archive

Does the water molecule only have hydrogen bonding intermolecular forces or does it also have dipole dipole forces - some websites say it does and some say it doesn't so I'm a bit confused. I originally though water doesnt have dipole dipole forces because its a symmetrical molecule...

both