hkdse 2014 chemistry paper ii - hkeaa · calculations • q. 2(b) (iii) percentage of caco. 3. by...
TRANSCRIPT
![Page 1: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/1.jpg)
HKDSE 2014 Chemistry Paper II
![Page 2: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/2.jpg)
Focus areas (Last year) • Basic chemical knowledge • Number of decimal places / significant figures • Unit presented in the question • Experimental work • Calculations • Presentation • Question requirement • Misconceptions
![Page 3: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/3.jpg)
Focus areas (This year) • Basic chemical knowledge • Number of decimal places / significant figures • Unit presented in the question • Experimental work • Calculations • Presentation • Question requirement • Misconceptions
![Page 4: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/4.jpg)
Basic Chemical Knowledge
• Part (a) of ALL Sections • Expectations: – One or two sentences will do. – No detailed explanations.
![Page 5: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/5.jpg)
Basic Chemical Knowledge
• Question 1 (a): – Activation energy?
– Yeast function? Why failure at high T?
– Obtaining Vitamin C industrially?
– Chloroalkali industry: 2 important chemicals
![Page 6: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/6.jpg)
Basic Chemical Knowledge
• Question 1(a) Activation energy
• Expected: minimum energy possessed by reactant molecules to start a reaction
Version B answer
Version A answer
![Page 7: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/7.jpg)
Basic Chemical Knowledge
• Question 1(a) (ii) Yeast function? …
• Expected: Yeast provides enzyme / catalyst which will be denatured at high temperature.
> half of the candidates neglected that enzymes would be denatured at high temperature.
![Page 8: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/8.jpg)
Basic Chemical Knowledge
• Version A answer:
• Version B answer:
![Page 9: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/9.jpg)
Basic Chemical Knowledge
• Q. 1(a) (iii) Vitamin C industrially?
• Expected: To solve the problems of inadequate or shrinking supply of vitamin C.
![Page 10: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/10.jpg)
Basic Chemical Knowledge
• Q.1(a) (iii) • Version A:
• Version B:
![Page 11: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/11.jpg)
Basic Chemical Knowledge
• Q. 1(a) (iv) 2 products of chloroalkali industry?
• Expected: Any two: hydrogen, chlorine, sodium hydroxide
• BUT NOT sodium chloride
![Page 12: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/12.jpg)
Basic Chemical Knowledge
• Q.1(a) (iv) • Version A:
• Version B:
![Page 13: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/13.jpg)
Basic Chemical Knowledge
• Question 2 (a): – ccp, bcc?
– 2 structural features … liquid crystal behaviour?
– Thermoplastics vs. thermosets
![Page 14: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/14.jpg)
Basic Chemical Knowledge
• Q.2 (a) (i) ccp, fcp
• Expected:
![Page 15: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/15.jpg)
Basic Chemical Knowledge
• Version A:
![Page 16: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/16.jpg)
Basic Chemical Knowledge • Q.2(ii) 2 structural features … liquid crystalbehaviour. • Expected: – Fairly rigid molecular backbone – Benzene rings – Rod‐like or disc‐like – Polar groups
• Version A
![Page 17: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/17.jpg)
Basic Chemical Knowledge
• Q.2(a)(iii) Thermoplastics vs. thermosetting plastics • Expected: – Thermoplastics: polyvinyl chloride, polystyrene
– Thermosetting plastics: urea‐methanal
About 1/4 of the candidates were not able to distinguish between thermoplastics and thermosetting plastics
![Page 18: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/18.jpg)
Basic Chemical Knowledge
• Version A
• Version B
![Page 19: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/19.jpg)
Basic Chemical Knowledge
• Question 3(a) – Chemical test for • HCl(g) • \
C = O
/
– Drying agent for ethyl ethanoate?
![Page 20: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/20.jpg)
Basic Chemical Knowledge
• Q.3(a) (i) Test for HCl(g)?
• Expected: – Place near NH3(g) – Dense white fume is observed.
• Not asking test for HCl(aq)
![Page 21: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/21.jpg)
Basic Chemical Knowledge
• Version A
• Version B
![Page 22: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/22.jpg)
Basic Chemical Knowledge
• Q.3(a) (ii) Test for carbonyl group?
• Expected: – Add 2,4‐dinitrophenylhydrazine. – Yellow / orange / red precipitate is formed.
• Not asking for ketone group.
![Page 23: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/23.jpg)
Basic Chemical Knowledge
• Version A
• Version B
![Page 24: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/24.jpg)
Basic Chemical KnowledgeQuestion 3(a) Drying agent: CH3CO2CH2CH3 • Question 3(a) Drying agent: CH3CO2CH2CH3?
• Expected: Anhydrous magnesium sulphate
• Not asking for explanation
• Version A:
![Page 25: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/25.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions
![Page 26: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/26.jpg)
Experimental work
• Q.1(b) Given: BrO3
‐ + 6I‐(aq) + 6H+(aq) 3I2(aq) + Br‐(aq) + 3H2O(l)
(i) Initial rate?
Expected: instantaneous rate at the start of the reaction
About three quarters of the candidates were not able to explain the term ‘initial rate’.
![Page 27: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/27.jpg)
Experimental work
• Version A:
• Version B:
![Page 28: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/28.jpg)
Experimental work • Q.1(b) Given: BrO3
‐ + 6I‐(aq) + 6H+(aq) 3I2(aq) + Br‐(aq) + 3H2O(l)
(ii) Method with justification to follow theprogress of I2(aq)? Expected: Follow colour intensity of the solution as the solution changes from colourless to brown.
![Page 29: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/29.jpg)
Experimental work
• Version A:
• Version B:
![Page 30: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/30.jpg)
Experimental work
• Q.3(c)(i) Experimental steps for purifying sample T containing organic acid as impurity by using NaHCO3(aq) and pentane?
Expected: T + pentane + NaHCO3 in a separating funnel. Shake. Collect the organic layer and carry out fractional distillation.
![Page 31: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/31.jpg)
Experimental Work
• Version A:
• Version B:
![Page 32: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/32.jpg)
Experimental work
• Version B:
![Page 33: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/33.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions
![Page 34: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/34.jpg)
Calculations • Question 1 (b) Order determination
Expected: Initial rate directly proportional to [BrO3
‐(aq)] Order = 1
![Page 35: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/35.jpg)
Calculations • Version A:
• Version B:
![Page 36: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/36.jpg)
Calculations • Q. 1(b) (iv) (1)
2
3
1084.11030.2
20.010.0
)30.0)(17.0()15.0)(17.0(
2rateinitial 1rateinitial
y Expected
![Page 37: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/37.jpg)
Calculations • Version A:
![Page 38: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/38.jpg)
Calculations • Version B:
![Page 39: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/39.jpg)
Calculations • Q.1(b)(iv) (2) Trial 1: initial rate w.r.t. BrO3
‐(aq)?
Expected: Initial rate of consumption of BrO3
‐(aq) = 2.30 x 10‐3 x 1/3 = 7.67 x 10‐4 mol dm‐3 s ‐1
![Page 40: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/40.jpg)
Calculations • Version A:
• Version B:
![Page 41: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/41.jpg)
Calculations • Q. 2(b) (iii) Percentage of CaCO3 by mass? • Expected: Amount of CaC2O4 formed in step 6 = 2.374/128.1 = 0.01853 mol
Mass of CaCO3 in limestone sample = 0.01853 (100.1) = 1.855 g Percentage of CaCO3 by mass = 1.855 (100)/2.025 = 91.6%
About half of the candidates were not able to calculate the percentage of CaCO3 by mass as they wrongly calculated the formula masses of calcium carbonate and calcium oxalate as they were not familiar with the chemical formulae for these two compounds
![Page 42: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/42.jpg)
Calculations • Version A:
![Page 43: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/43.jpg)
Calculations • Version B:
![Page 44: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/44.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions
![Page 45: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/45.jpg)
Presentation
• 3 (c) (ii) Interpretation of IR spectrum + given information
![Page 46: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/46.jpg)
Presentation
• (1) negative test with Tollen’s Reagent ???
• (2) strong absorption peak at 1730 cm‐1 ???
• (3) Absence of some important peaks ???
![Page 47: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/47.jpg)
Presentation • Expected: • (1) negative test with Tollen’s Reagent
no aldehyde group • (2) strong absorption peak at 1730 cm‐1
presence of C=O with (1), ketone group present
• (3) Absence of some important peaks 2070 – 2250 cm‐1: no CC group 1610 – 1680 cm‐1: no C=C group 3230 – 3670 cm‐1: no –OH group
About three‐quarters of the candidates failed to identify the functional group that may be present in T.
![Page 48: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/48.jpg)
Presentation
• Version A:
![Page 49: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/49.jpg)
Presentation
• Version B:
![Page 50: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/50.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions
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Question requirement • 1 (c) (vi) … a lot of natural nitrate mines. … success of the Haber process … led to some impacts… Suggest one impact. • Expected:
The mining work was no longer profitable / mining work might be closed / it could lead to a high unemployment rate
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Question requirement • Version A:
• Version B
![Page 53: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/53.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions
![Page 54: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/54.jpg)
Misconceptions • 1 (c) (v) One design to increase the overall conversion percentage of nitrogen?
Expected: reuse unreacted reactants recycle the reactants removing ammonia from the product mixture
Some wrongly suggested: “dissolving ammonia in water ”.
![Page 55: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/55.jpg)
Misconceptions • Version A:
• Version B:
![Page 56: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/56.jpg)
Misconceptions • Q.2(c) (i) moulding method?
• Expected: Blow moulding About two‐thirds of the candidates provided wrong answers: compression moulding
• Version A:
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Misconceptions • Q.2(c) (ii) 2 common types of PE
• Expected: High density polyethene & Low density polyethene
Two‐thirds of candidates provided answers: PVC / PS / PP as types of PE
• Version A:
![Page 58: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/58.jpg)
Misconceptions • Q.2(c) (iv) Given: PLA
• (1) structure of lactic acid
• Expected:
• Version A:
About two‐thirds drew incorrect structures.
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Misconceptions • 3(c) (iii) mass spectrum of T, strong peaks at 43 and 91; parent peak : 134. m/z = 43 & m/z 134???
Expected: 43 : [CH3CO]+
134: [C7H7COCH3]+
Some candidates did not aware these species are positively charged.
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Misconceptions • Version A:
• Version B:
![Page 61: HKDSE 2014 Chemistry Paper II - HKEAA · Calculations • Q. 2(b) (iii) Percentage of CaCO. 3. by mass? • Expected: Amountof CaC. 2. O. 4. formed in step 6 = 2.374/128.1 = 0.01853](https://reader036.vdocuments.us/reader036/viewer/2022071107/5fe1955a4ef82f2ef10c4058/html5/thumbnails/61.jpg)
Focus areas • Basic chemical knowledge
• Experimental work
• Calculations • Presentation
• Question requirement • Misconceptions