Chemistry Predictions/Thoughts (2 Viewers)

[hughjanus_]

The reason that a Keq value of 0.53 is incorrect is due to the fact that you can’t do 0.1 - [BrCH2COOH](aq) to calculate [BrCH2COOH](octanol). This is because of the keyword “an AQUEOUS solution of 0.1M bromoacetic acid is shaken with an equal volume of octan-1-ol. This means that the concentration of bromoacetic acid in the entire solution is 0.05 M. Thus, instead of calculating the concentration of bromoacetic acid in water this way, you must instead replace [BrCH2COOH](aq) in the Ka expression with (0.1 - 9.18*10^3 - x) where x is [BrCH2COOH](octanol).

Because the concentration of bromoacetic acid in octanol and in water are not contributing to a singular molarity, it isn’t possible to do a simple 0.1 - [BrCH2COOH](aq) to solve the question.

 

[appleali]

guys i only answered mc but i think i got full marks can i state rank?

 

[potpal]

u like it rough dont u, slow and hard

yeah no fr i don’t know what’s up with me, maybe im secretly a masochist

 

[femboys4life]

i thought it depends on ur whole hsc mark, which includes internals- otherwise wouldnt there be like 50-60 ppl all tied on 100 for chem/mx1/mx2?

but how do those ppl who internally are like 20th end up state ranking where everyone ahead of them doesnt like u always hear those stories

 

[femboys4life]

yeah no fr i don’t know what’s up with me, maybe im secretly a masochist

that makes 2 of us bbg my dms r free anytime

 

[GAHHHHHHHHHHHHHHHHHHHHHHH]

have answers been posted yet?

 

[Ishi081]

have answers been posted yet?

no I dont think so

 

[Ishi081]

what did people say for 27 - the barium and lead question

 

[Bobweo]

What was the answer for Q2(cycad leaching stuff) and 17(titration curve, identify acid) for MCQ?

 

[leclerc16]

what did people say for 27 - the barium and lead question

barium and lead precipitate with the sulfate so its invalid

 

[leclerc16]

What was the answer for Q2(cycad leaching stuff) and 17(titration curve, identify acid) for MCQ?

i put B for 2 and C for 17

 

[Bobweo]

Same, but why did Q2 option B say low solubility toxin, I thought cycasin was highly soluble?

 

[ManifestationIsKey]

Same, but why did Q2 option B say low solubility toxin, I thought cycasin was highly soluble?

Lol I was hesitant putting B as well because I thought that was contradictory, but ended up putting it anyway.

 

[herbimycin]

surely someone has solutions up by now?

 

[thericemanhypothesis]

The reason that a Keq value of 0.53 is incorrect is due to the fact that you can’t do 0.1 - [BrCH2COOH](aq) to calculate [BrCH2COOH](octanol). This is because of the keyword “an AQUEOUS solution of 0.1M bromoacetic acid is shaken with an equal volume of octan-1-ol. This means that the concentration of bromoacetic acid in the entire solution is 0.05 M. Thus, instead of calculating the concentration of bromoacetic acid in water this way, you must instead replace [BrCH2COOH](aq) in the Ka expression with (0.1 - 9.18*10^3 - x) where x is [BrCH2COOH](octanol).

Because the concentration of bromoacetic acid in octanol and in water are not contributing to a singular molarity, it isn’t possible to do a simple 0.1 - [BrCH2COOH](aq) to solve the question.

But the alcohol and water don't mix so wouldn't you not consider the entire volume? Just the halves that go to the water and alcohol respectively

 

[lawnmower&pencilcase]

For question 36 - the calculating the enthalpy of reaction between HCL and NaHCO3 - does the mass include the 14.7g NaHCO3 and the mass of the solution? do you also have to minus the CO2 produced?

 

[Bobweo]

For question 36 - the calculating the enthalpy of reaction between HCL and NaHCO3 - does the mass include the 14.7g NaHCO3 and the mass of the solution? do you also have to minus the CO2 produced?

I added mass of HCL and carbonate for mass of solution.

 

[farenheit_541]

For question 36 - the calculating the enthalpy of reaction between HCL and NaHCO3 - does the mass include the 14.7g NaHCO3 and the mass of the solution? do you also have to minus the CO2 produced?

idk- i didnt, but i think it works out to like 4 g of Na in the solution at the end, so its not like its insignificant

 

[shoulfer]

surely someone has solutions up by now?

surely

 

[help2024]

Do we have to add the mass of the solid?