HL Chemistry paper 1 and 2

[Megamind]

 

 

 

(TZ2) I'm super frustrated with the amount of silly errors I made in paper 2 (not reading the question properly, unit conversions etc.) I hope it won't have cost me a 7. I cannot remember which question this was, probably 9, but we had to work out the bond angle of SF4. I got the shape right but I never learnt or came across bond angles for see saw shapes so I guessed 107. What did you guys get for that?

I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon?

Shared pair of electrons closer attracted to carbon due to its higher electro negativity though I squeezed that last bit in right at the end, may not get the mark. Regarding the percentage error, I got 60 but I used 0.05 not 0.025 mol to work out delta H (the first of my silly mistakes!!) I believe the correct answer is around 20%.

 

For the delta T I wrote 6 degrees, which I only noticed the last 5 min. But with that I got 22%, so 20% sounds about right... Hopefully I only lose the one point on the delta T but get the points with ECF

 

 

 

I got Del T = 5.2 C? Did you extrapolate the line of best fit from the max temperature on to the y axis and use that temperature reading or directly use the highest reading on the graph (and then subtracting from the same initial reading)? 

 

Also what were your major sources of error? I wrote heat loss to the environment, and use of a styrofoam cup to minimize heat loss. 

[Runner22909]

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

[sam1996]

(TZ2) I'm super frustrated with the amount of silly errors I made in paper 2 (not reading the question properly, unit conversions etc.) I hope it won't have cost me a 7. I cannot remember which question this was, probably 9, but we had to work out the bond angle of SF4. I got the shape right but I never learnt or came across bond angles for see saw shapes so I guessed 107. What did you guys get for that?

I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon?

Shared pair of electrons closer attracted to carbon due to its higher electro negativity though I squeezed that last bit in right at the end, may not get the mark. Regarding the percentage error, I got 60 but I used 0.05 not 0.025 mol to work out delta H (the first of my silly mistakes!!) I believe the correct answer is around 20%.

Well I wrote that it was dative covalent bond but Im not sure wHy I wrote it

I thought about it but decided not to. Was a slightly odd question anyway and two marks I believe, so I'm sure you'll bag one

[dorianb]

 

 

 

 

(TZ2) I'm super frustrated with the amount of silly errors I made in paper 2 (not reading the question properly, unit conversions etc.) I hope it won't have cost me a 7. I cannot remember which question this was, probably 9, but we had to work out the bond angle of SF4. I got the shape right but I never learnt or came across bond angles for see saw shapes so I guessed 107. What did you guys get for that?

I said the same thing. 107 for one and <120 and<180 for the other one.both had a lone pair. What did you writr for the question were they asked about the covalent bond between hydrogen and carbon?

Shared pair of electrons closer attracted to carbon due to its higher electro negativity though I squeezed that last bit in right at the end, may not get the mark. Regarding the percentage error, I got 60 but I used 0.05 not 0.025 mol to work out delta H (the first of my silly mistakes!!) I believe the correct answer is around 20%.

 

For the delta T I wrote 6 degrees, which I only noticed the last 5 min. But with that I got 22%, so 20% sounds about right... Hopefully I only lose the one point on the delta T but get the points with ECF

 

 

 

I got Del T = 5.2 C? Did you extrapolate the line of best fit from the max temperature on to the y axis and use that temperature reading or directly use the highest reading on the graph (and then subtracting from the same initial reading)? 

 

Also what were your major sources of error? I wrote heat loss to the environment, and use of a styrofoam cup to minimize heat loss. 

 

I wrote 6, but you are right, it was 5.2, but only noticed that right before the end... And I used 30 cm^3 as the volume of HCl, as that was when the temperature was at its highest - I didnt get what they wanted us to do with the line

[dorianb]

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

Looks about right.. I didnt extrapolate, and used the volume where the temperature was the highest - so 30 cm^3... 

[2to10]

(TZ1) For paper 1, what was the answer to what would change the Kc value. I put C (increase in concentration) but I'm not sure.

There was another question where there was two arrows. It went something like hydrocarbon -- X -- CH3CH2NH2 and said find x? Does anyone remember it.

 

For paper 2, I remember doing 6 and 8 for section B.

 

I wasn't sure about the economic need for catalyst in the contact process on question 6? 

Left a whole pH question blank even though I knew the ph = pKa - [weak acid]/[base]

[Ossih]

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly  

[ketone]

 

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

 

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

[Runner22909]

This is what I think: The temperature stopped rising after 27 mL because there was nothing left to neutralize; the reaction went to completion when 27 mL of NaOH reacted with 25 mL of HCl. This is why the slope of the graph decreased in between 25 to 30 mL. Therefore the mass used should be 27 + 25 because these were the masses involved in the reaction.

[sam1996]

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

It said 1 mol of hydrogen gas and the answer was D, I am 100% sure because I was aware of these questions after getting them wrong all the time in past papers. Also, I do actually remember the first question on paper 2 said "determine the volume by drawing lines on the graph" because that instruction probably saved me.

[ketone]

 

 

 

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

It said 1 mol of hydrogen gas and the answer was D, I am 100% sure because I was aware of these questions after getting them wrong all the time in past papers. Also, I do actually remember the first question on paper 2 said "determine the volume by drawing lines on the graph" because that instruction probably saved me.

 

 

This is what I think: The temperature stopped rising after 27 mL because there was nothing left to neutralize; the reaction went to completion when 27 mL of NaOH reacted with 25 mL of HCl. This is why the slope of the graph decreased in between 25 to 30 mL. Therefore the mass used should be 27 + 25 because these were the masses involved in the reaction.

Thanks for your explanation. This affects part (b) of it too. Hope ECF applies. 

[Baller97]

 

 

 

 

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

It said 1 mol of hydrogen gas and the answer was D, I am 100% sure because I was aware of these questions after getting them wrong all the time in past papers. Also, I do actually remember the first question on paper 2 said "determine the volume by drawing lines on the graph" because that instruction probably saved me.

 

 

This is what I think: The temperature stopped rising after 27 mL because there was nothing left to neutralize; the reaction went to completion when 27 mL of NaOH reacted with 25 mL of HCl. This is why the slope of the graph decreased in between 25 to 30 mL. Therefore the mass used should be 27 + 25 because these were the masses involved in the reaction.

Thanks for your explanation. This affects part (b) of it too. Hope ECF applies. 

 

It better Or we're screwed for that question hahah

[ketone]

 

 

 

 

 

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

It said 1 mol of hydrogen gas and the answer was D, I am 100% sure because I was aware of these questions after getting them wrong all the time in past papers. Also, I do actually remember the first question on paper 2 said "determine the volume by drawing lines on the graph" because that instruction probably saved me.

 

 

This is what I think: The temperature stopped rising after 27 mL because there was nothing left to neutralize; the reaction went to completion when 27 mL of NaOH reacted with 25 mL of HCl. This is why the slope of the graph decreased in between 25 to 30 mL. Therefore the mass used should be 27 + 25 because these were the masses involved in the reaction.

Thanks for your explanation. This affects part (b) of it too. Hope ECF applies. 

 

It better Or we're screwed for that question hahah

 

that was a tricky one, btw did u know the answer for paper 1 question 2 abt combustion? I filled in B. 

[sam1996]

Here's my calculation for TZ2, Q1 on P2, if I recall correctly:

 

By drawing a best fit line, I got 27 mL (which is logical because the temperature stopped rising at some point between 25 and 30 mL, because there was nothing left to neutralize with);

temperature change was 5.2 by calculating the difference between the initial and highest reading;

 

Q = mcT

m = (27 + 25) mL = 52 g

c = 4.18

T = 5.2

 

Q = 1130.3 J

n = 0.025 mol

 

H = Q/n = -1130.3 / 0.025 = -45200 J = -45.2 J

 

Percentage error = (58-45.2)/58 = ±22%

 

I also wrote heat loss to environment, and conduct the experiment in a thermal insulator to minimize heat loss.

 

I got this exactly

really 27 ml? i thought it should be 30ml lol, as it was the highest temp? yet I know it it is that simple, IB wont even tell us to draw a line though.

 

Btw, for TZ2 pp1, I didt rmb clearly if it is 1 mol of hydrogen atoms or 1 mol of hydrogen gas. if its atoms then ans shud be C .

It said 1 mol of hydrogen gas and the answer was D, I am 100% sure because I was aware of these questions after getting them wrong all the time in past papers. Also, I do actually remember the first question on paper 2 said "determine the volume by drawing lines on the graph" because that instruction probably saved me.

 

This is what I think: The temperature stopped rising after 27 mL because there was nothing left to neutralize; the reaction went to completion when 27 mL of NaOH reacted with 25 mL of HCl. This is why the slope of the graph decreased in between 25 to 30 mL. Therefore the mass used should be 27 + 25 because these were the masses involved in the reaction.

Thanks for your explanation. This affects part (b) of it too. Hope ECF applies.

It better Or we're screwed for that question hahah

that was a tricky one, btw did u know the answer for paper 1 question 2 abt combustion? I filled in B.

It was the one with 3y/4, whichever one that was

[mhelof]

SOOOO I answered numbers 7 and 10 in Section B... annnnd I didn't solve the last page (from number 10) because I didn't see it.. Great. 

So, how was the Chemistry paper. I was in TZ2 I think, and the paper 1 was quite hard to be honest

Let's hope the grade boundaries go low this year

 

I answered 7 and 10 as well : ) 

 

Oh, I actually thought that P1 was quite easy (but maybe it's just my feeling!). However, don't you think that there was a mistake in the spontaneity question?

[Baller97]

Guys... I have a feeling we all screwed up pretty bad in one way or another. Let's hope the grade boundaries drop ....alot.

How was paper 3 though??

[ketone]

Guys... I have a feeling we all screwed up pretty bad in one way or another. Let's hope the grade boundaries drop ....alot.

How was paper 3 though??

I did option A and B. Difficulties are similar to past years I think.

[mhelof]

I did option B and E... they were alright I think. Better than other papers : )

[ketone]

I did option B and E... they were alright I think. Better than other papers : )

 what did you get for question of the comparing structures of ketone and aldosterone? 

[mhelof]

 

I did option B and E... they were alright I think. Better than other papers : )

 what did you get for question of the comparing structures of ketone and aldosterone? 

 

Ketone and aldosterone? Did you mean cholesterol and aldosterone?