Predictions for Chemistry 2014 HSC? (9 Viewers)

[enigma_1]

You need one reactant in excess to ensure that they both react or something. Not too important

 

[faisalabdul16]

To shift equilibrium fwd you mean!!

i don't think you have to add more of the alkanol. All it does it shift equilibrium to the right, but it's not cost effective.

Equal volumes are used guys.

 

[enigma_1]

To shift equilibrium fwd you mean!!

Actually yes that's right!

 

[seventhroot]

. do this guys.

the answer is C


when in doubt; pick C

 

[QZP]

A

 

[zhertec]

I could have sworn that seventhroot did not do chem for HSC..but I might be wrong lol

 

[seventhroot]

I could have sworn that seventhroot did not do chem for HSC..but I might be wrong lol

why do you say that?

why can't I do chem? cos I'm black?






















I didn't do chem

 

[faisalabdul16]

A

Correct

Guys SEVENTHROOT DID NOT DO CHEMISTRY. HE IS A TROLL.

 

[photastic]

Correct

Guys SEVENTHROOT DID NOT DO CHEMISTRY. HE IS A TROLL.

Explanation please.

 

[QZP]

Industrial (Contact process): Did you guys learn about the several stages (the multiple layers of V2O5 catalyst and how each one has a dif temp condition) during the conversion of 2SO2 + O2 <--> 2SO3? Or did you learn that it was just simply in one step

 

[Speed6]

Correct

Guys SEVENTHROOT DID NOT DO CHEMISTRY. HE IS A TROLL.

His too good for chem that's y your saying this.

 

[SuchSmallHands]

Solutions containing nickel (II) ions were analysed by AAS. A standard solution of

5 ppm nickel had an absorbance of 0.200. A second solution of unknown

concentration was found to have an absorbance of 0.500.

100 mL of this second solution was reacted with excess sodium carbonate solution.

The precipitate formed was weighed and dried.

What mass of precipitate formed?

(A) 2.5 x 10^-3

(B) 1.3 x 10^-3

(C) 1.7 g

(D) 2.5 g

Got D. Tried to work out where I went wrong for a solid 10 minutes. Realised at some point I decided to swap from using milligrams to using grams. Band 6 student.

 

[seventhroot]

Correct

Guys SEVENTHROOT DID NOT DO CHEMISTRY. HE IS A TROLL.

yes I did;

umadbrO?

fail camera/10; soz

gg no re

 

[zhertec]

I think we learnt it as one step with appropriate conditions i.e. 450 degrees celsius, 1.5-2 atm and excess of oxygen.

 

[faisalabdul16]

Industrial (Contact process): Did you guys learn about the several stages (the multiple layers of V2O5 catalyst and how each one has a dif temp condition) during the conversion of 2SO2 + O2 <--> 2SO3? Or did you learn that it was just simply in one step

Several Stages -
1) Passed over catalytic bed at 450 degrees, 70% conversion
2) Passed over a second catalytic bed at 400 degrees, 97% conversion
3) Passed over third catalytic bed at 350 degrees, 99.7% conversion

 

[QZP]

Well goodluck with this Q (taken from a 2014 commercial paper):

 

[faisalabdul16]

Does anyone have any 2014 papers that they could upload or message me? Will be appreciated.

 

[seventhroot]

Does anyone have any 2014 papers that they could upload or message me? Will be appreciated.

have you done all the 2013 ones?

 

[faisalabdul16]

Well goodluck with this Q (taken from a 2014 commercial paper): View attachment 30993

The conversion of sulfur dioxide to sulfur trioxide is an equilibrium reaction, involving a fine delicate balance between a set of compromise conditions which maximise the yield at the smallest cost possible. 2SO2(g) + O2(g) (equilibrium) 2SO3(g) + heat. (catalyst = vanadium oxide). Increasing the temperature or the pressure of the reaction vessel increases the rate of reaction as it provides more kinetic energy for successful collisions between particles to occur. However, increasing temperature, causes equilibrium to shift to the left, favouring the reverse reaction, producing more of the reactants and thus a lower sulfur trioxide yield. Hence why compromise conditions of 450 degrees celsius are enforced. Increasing the pressure not only increases the rate of reaction, but also the yield because of the 3 to 2 mol ratio of gases, with equilibrium shifting to the right hand side as it contains the lesser number of moles of gas. But, due to economical reasons, cost savings and for safety, only pressures of 1-2 atmospheres are enforced in this reaction vessel. The yield of sulfur trioxide could be also increased through the removal of the product, causing equilibrium to shift to the right and produce more sulfur trioxide. One factor that industrial chemists have manipulated and enforced, to acquire maximum yield is through decreasing the temperature while subsequently passing it over catalytic beds of vanadium oxide. Chemists, pass it over a first catalytic bed at 450 degrees celsius and have a 70% conversion rate of sulfur dioxide to sulfur trioxide. Lowering temperatures increases yield however decreases the rate, but passing it over a second catalytic bed counteracts that dilemma, converting sulfur dioxide into 97% sulfur trioxide, and finally a third conversion results in 99.7% sulfur trioxide formation. These steps are necessary as it allows for maximum yield to be produced in a cheap and economically viable manner, thus leading to increased gains and profits.

 

[faisalabdul16]

have you done all the 2013 ones?

with the commercial papers yes, and like 2 selective schools, but i am limited in the number of papers i have.