Edexcel IAL Chemistry Unit 2 (WBIO2) / June 10th 2016

First one was 120, shape is trigonal planar.

Next one is a tetrahedral shape with an angle of 107 degrees.

What were the answers to the Multiple Choice Questions:

1. About how many peaks 1,2 dichloroethane had - I wrote 3 but not sure.
2. How many moles of Sodium Sulfate reacted - I wrote 1.00 mol but I'm pretty sure I'm wrong due to the wrong method I think I used.

Also the question that asked to draw the structure of ClO7 - how many marks was that?

Damn that was quite a hard exam!

In section c they mention some compound and why they are not used as solvent do you guys remember it ?

Molecular ion peak is 3.
IR spectra produced belonged to propanone.
Mass of Iodine 114.2g.
Percentage Uncertainty: 1%
Sodium Sulfate moles : 0.33 (not sure of the answer).
Structure of Cl2O7 : Google it. Its on wikipedia.

Paper was not that bad. What was the White solid produced at step 3? I wrote BaO.

i wrote the same BaO for stage 3
for the last question, i i did no change for titre and a smaller change for iodine
i used the first paragraph in the question were it said something about the unsaturation and iodine

These are my model answers and I cannot guarantee that all are right. They do not follow the order in which they came.MULTIPLE CHOICE: the question on mass spectrum : 29 m/e was propan-1-ol and proanal. 31 m/e was propan-1-ol. Infrared question it was propanone. The one for anthropogenic climate was CO2. The one that was polar was difluorodichloroethane. The bond angle question was sulfur hexafluoride. The one for bromide and h2so4 was H2S. The one for the maxwell distribution was moves to the left and has higher peak. The question on equilibrium. A decrease in temperature would cause an increase in the yield of CO and no change in the rate of reaction as equilibrium does not make it faster. Increase in pressure would increase rate but not yield. The one on why ethanol is more soluble than hexan-1-ol was because of london forces being more stronger than in ethanol. question on concentration of NA2so4 was 1moldm-3. The question on the number of molecular ion peaks would be 3. The one for which one would not show colour change in sodium dichromate was propanone. The question on what does magnesium give when it burns was MgO only. The one for trends of hydroxides and sulfates was hydroxides increase sulfates decreases. The one for what is the trend as group 7 is descended was a decrease and then an increase in boiling temp. The percentage uncertainty was 1percent. The one that reacts with ozone or something was difluorodichloromethane (NOT SURE WHETHER THIS WAS THE QUESTION) I don't remember two questions. If anyone does post and i will answer.Short answered: first one was trigonal planar bond angle 120the next question only asked for the bond angle which was 107. You also had to draw the structure. Reason was 1 lone pair and two bonding pairs. Lone pair repels more than bonding pairs hence causes tetrahedral bond angle to reduce.oxidation number of CL was +7the structure can be found on google.the product was HCLO4.The question on rates of reaction was as follows.Need ethanol to dissolve both AgNO3 and the halogenoalkane. Butan-1-ol formed. Also the question on ionic equation was Ag+ + Br- gives AgBr(State symbols were AQ AQ and S).The colour of the precipitate was yellow(AgI). With AgCl, aqueous and conc ammonia ppt dissolves. In AgI, yellow ppt remains. The speed was C,B,A. the polarity of the bonds does not change down the group. Hence cannot be used as a test of rates. Use bond strength. this determines the rate of reaction. The question on flame tests was yellow-red and apple green. The reason for Ca(NO3)2 was that Ca2+ ion is smaller than the barium ion. This means that Ca(2+) has more polarizing power hence polarizes the anion more. This leads to more covalent character and hence easily decomposed. To check the decomposition of anhydrous Ca(NO3)2 and the other compound, you could use over water method and ensure you have a graduated test-tube to earn the mark. Precautions were use the same amounts of both and ensure the testubes were at the same distance to avoid being unfair. The two reactions were alcohol plus nh3 gave dibutylamine and HBr. the structure was simple (C4h9)2NH. Section Cthe first one was skeletal formula which i dont remember. The reason for the higher boiling point: Both have dipole dipole forces(permanent) but one of them had more electrons and hence stronger london forces. why is ICL stored?--SO as to prevent it from decomposing(UV light reaching it) Why is ICl preferred. THis is because icl exists as I2 and Cl2 under equilibrium so more reactive. WHy is starch not needed. No iodine evolved and so no indicator needed. Colour change before starch added. Yellow to colourless. The first calc was 4x10-3 mol. The second one was 2x10-3 mol. the reacted moles were 9x10-4 mol. Use ratios. Hence with 100g it would have been 0.45 mol. Mass that reacted was 114.21g. The last question was lower iodine value, higher titre value.

Yes
It was about why trichloromethane and 1,1,1-trichloroethane are no longer used as solvents

What was your answer ?

instead of cba i wrote AgI, AgBr, AgCl
do you think itll be accepted?
didnt read the question properly because i was rushing it :/

For the brown bottle question I wrote "to prevent it from reacting with light". Will I get a mark for not mentioning UV?

I think I skipped that because I couldn't think of anything logical :P
what was yours? ^_^

I wrote it could react with most substances forming products idk if it makes sense 😁😁

No the hydrated salt was being decomposed in stage 1

These are my model answers and I cannot guarantee that all are right. They do not follow the order in which they came.MULTIPLE CHOICE: the question on mass spectrum : 29 m/e was propan-1-ol and proanal. 31 m/e was propan-1-ol. Infrared question it was propanone. The one for anthropogenic climate was CO2. The one that was polar was difluorodichloroethane. The bond angle question was sulfur hexafluoride. The one for bromide and h2so4 was H2S. The one for the maxwell distribution was moves to the left and has higher peak. The question on equilibrium. A decrease in temperature would cause an increase in the yield of CO and no change in the rate of reaction as equilibrium does not make it faster. Increase in pressure would increase rate but not yield. The one on why ethanol is more soluble than hexan-1-ol was because of london forces being more stronger than in ethanol. question on concentration of NA2so4 was 1moldm-3. The question on the number of molecular ion peaks would be 3. The one for which one would not show colour change in sodium dichromate was propanone. The question on what does magnesium give when it burns was MgO only. The one for trends of hydroxides and sulfates was hydroxides increase sulfates decreases. The one for what is the trend as group 7 is descended was a decrease and then an increase in boiling temp. The percentage uncertainty was 1percent. The one that reacts with ozone or something was difluorodichloromethane (NOT SURE WHETHER THIS WAS THE QUESTION) I don't remember two questions. If anyone does post and i will answer.Short answered: first one was trigonal planar bond angle 120the next question only asked for the bond angle which was 107. You also had to draw the structure. Reason was 1 lone pair and two bonding pairs. Lone pair repels more than bonding pairs hence causes tetrahedral bond angle to reduce.oxidation number of CL was +7the structure can be found on google.the product was HCLO4.The question on rates of reaction was as follows.Need ethanol to dissolve both AgNO3 and the halogenoalkane. Butan-1-ol formed. Also the question on ionic equation was Ag+ + Br- gives AgBr(State symbols were AQ AQ and S).The colour of the precipitate was yellow(AgI). With AgCl, aqueous and conc ammonia ppt dissolves. In AgI, yellow ppt remains. The speed was C,B,A. the polarity of the bonds does not change down the group. Hence cannot be used as a test of rates. Use bond strength. this determines the rate of reaction. The question on flame tests was yellow-red and apple green. The reason for Ca(NO3)2 was that Ca2+ ion is smaller than the barium ion. This means that Ca(2+) has more polarizing power hence polarizes the anion more. This leads to more covalent character and hence easily decomposed. To check the decomposition of anhydrous Ca(NO3)2 and the other compound, you could use over water method and ensure you have a graduated test-tube to earn the mark. Precautions were use the same amounts of both and ensure the testubes were at the same distance to avoid being unfair. The two reactions were alcohol plus nh3 gave dibutylamine and HBr. the structure was simple (C4h9)2NH. Section Cthe first one was skeletal formula which i dont remember. The reason for the higher boiling point: Both have dipole dipole forces(permanent) but one of them had more electrons and hence stronger london forces. why is ICL stored?--SO as to prevent it from decomposing(UV light reaching it) Why is ICl preferred. THis is because icl exists as I2 and Cl2 under equilibrium so more reactive. WHy is starch not needed. No iodine evolved and so no indicator needed. Colour change before starch added. Yellow to colourless. The first calc was 4x10-3 mol. The second one was 2x10-3 mol. the reacted moles were 9x10-4 mol. Use ratios. Hence with 100g it would have been 0.45 mol. Mass that reacted was 114.21g. The last question was lower iodine value, higher titre value.

I wrote BaO but then crossed it out and wrote Ba(NO3)2 because they said in the question that it the solid melts or something like that and that the BaO was left in the test tube in the last step

These are my model answers and I cannot guarantee that all are right. They do not follow the order in which they came.MULTIPLE CHOICE: the question on mass spectrum : 29 m/e was propan-1-ol and proanal. 31 m/e was propan-1-ol. Infrared question it was propanone. The one for anthropogenic climate was CO2. The one that was polar was difluorodichloroethane. The bond angle question was sulfur hexafluoride. The one for bromide and h2so4 was H2S. The one for the maxwell distribution was moves to the left and has higher peak. The question on equilibrium. A decrease in temperature would cause an increase in the yield of CO and no change in the rate of reaction as equilibrium does not make it faster. Increase in pressure would increase rate but not yield. The one on why ethanol is more soluble than hexan-1-ol was because of london forces being more stronger than in ethanol. question on concentration of NA2so4 was 1moldm-3. The question on the number of molecular ion peaks would be 3. The one for which one would not show colour change in sodium dichromate was propanone. The question on what does magnesium give when it burns was MgO only. The one for trends of hydroxides and sulfates was hydroxides increase sulfates decreases. The one for what is the trend as group 7 is descended was a decrease and then an increase in boiling temp. The percentage uncertainty was 1percent. The one that reacts with ozone or something was difluorodichloromethane (NOT SURE WHETHER THIS WAS THE QUESTION) I don't remember two questions. If anyone does post and i will answer.Short answered: first one was trigonal planar bond angle 120the next question only asked for the bond angle which was 107. You also had to draw the structure. Reason was 1 lone pair and two bonding pairs. Lone pair repels more than bonding pairs hence causes tetrahedral bond angle to reduce.oxidation number of CL was +7the structure can be found on google.the product was HCLO4.The question on rates of reaction was as follows.Need ethanol to dissolve both AgNO3 and the halogenoalkane. Butan-1-ol formed. Also the question on ionic equation was Ag+ + Br- gives AgBr(State symbols were AQ AQ and S).The colour of the precipitate was yellow(AgI). With AgCl, aqueous and conc ammonia ppt dissolves. In AgI, yellow ppt remains. The speed was C,B,A. the polarity of the bonds does not change down the group. Hence cannot be used as a test of rates. Use bond strength. this determines the rate of reaction. The question on flame tests was yellow-red and apple green. The reason for Ca(NO3)2 was that Ca2+ ion is smaller than the barium ion. This means that Ca(2+) has more polarizing power hence polarizes the anion more. This leads to more covalent character and hence easily decomposed. To check the decomposition of anhydrous Ca(NO3)2 and the other compound, you could use over water method and ensure you have a graduated test-tube to earn the mark. Precautions were use the same amounts of both and ensure the testubes were at the same distance to avoid being unfair. The two reactions were alcohol plus nh3 gave dibutylamine and HBr. the structure was simple (C4h9)2NH. Section Cthe first one was skeletal formula which i dont remember. The reason for the higher boiling point: Both have dipole dipole forces(permanent) but one of them had more electrons and hence stronger london forces. why is ICL stored?--SO as to prevent it from decomposing(UV light reaching it) Why is ICl preferred. THis is because icl exists as I2 and Cl2 under equilibrium so more reactive. WHy is starch not needed. No iodine evolved and so no indicator needed. Colour change before starch added. Yellow to colourless. The first calc was 4x10-3 mol. The second one was 2x10-3 mol. the reacted moles were 9x10-4 mol. Use ratios. Hence with 100g it would have been 0.45 mol. Mass that reacted was 114.21g. The last question was lower iodine value, higher titre value.

Hey thanks so much for this! Can I just ask, you know for the MCQ about Maxwell Distribution curve, wasn't the question about what would happen if temperature increased? Because in that case the peak would move down and right. Also for the ionic equation of Ag+I- did it say that you have to include state symbols?

It said decreased and yes you had to include state symbols.