NATIONAL SENIOR CERTIFICATE (NSC) GRADE 11 MID-YEAR EXAMINATION PHYSICAL SCIENCES PAPER 2 (CHEMISTRY) (NSC11-11) D B

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1 PHYHIG211 NATIONAL SENIOR CERTIFICATE (NSC) GRADE 11 MID-YEAR EXAMINATION PHYSICAL SCIENCES PAPER 2 (CHEMISTRY) (NSC11-11) D B TIME: 09H00 12H00 TOTAL: 150 MARKS DURATION: 3 HOURS DATE: 13 JUNE 2013 This question paper consists of 15 pages. ICG 1 NSC Grade 11

2 INSTRUCTIONS AND INFORMATION Read the following instructions carefully before answering the questions: 1. Write your name and student number in the appropriate spaces on the ANSWER SHEET and ANSWER BOOK. 2. Answer ALL the questions. 3. Answer SECTION A on the attached ANSWER SHEET. 4. Answer SECTION B in the ANSWER BOOK. 5. Non-programmable calculators may be used. 6. Appropriate mathematical instruments may be used. 7. Number the answer correctly according to the numbering system used in this question paper. 8. Data sheets are attached for your use. 9. Give brief motivations, discussions, et cetera where applicable. 10. Please write neatly we cannot mark illegible handwriting. 11. Any student caught cheating will have his or her examination paper and notes confiscated. The College will take disciplinary measures to protect the integrity of these examinations. 12. If there is something wrong with or missing from your question paper or your answer book, please inform your invigilator immediately. If you do not inform your invigilator about a problem, the College will not be able to rectify it afterwards, and your marks cannot be adjusted to allow for the problem. 13. This question paper may be removed from the examination hall after the examination has taken place. This question paper consists of TWO sections: Section A and Section B. Answer ALL the questions. Question Section Marks A: Multiple-choice questions 1 20 Answer the question B: SEVEN direct questions Answer ALL the questions 7 8 TOTAL MARKS: 150 ICG 2 NSC Grade 11

3 SECTION A (20 MARKS) ANSWER THE QUESTION NOTE: Answer this section on the attached ANSWER SHEET. QUESTION 1 MULTIPLE-CHOICE QUESTIONS Four possible options are provided as answers to the following questions. Each question has only ONE correct answer. Choose the answer and make a cross (X) in the block (A. D.) next to the question number ( ) on the attached ANSWER SHEET. 1.1 A hydride of nitrogen has a molar mass of 17 g.mol 1. The correct molecular formula of the hydride is: + NH 4 A. B. NO2 C. NH 3 D. HN 3 (2) 1.2 Real gasses deviate from ideal gas behaviour under conditions of: A. high pressure and low temperature. B. high pressure and high temperature. C. low pressure and low temperature. D. low pressure and high temperature. (2) 1.3 Which one of the following is a polar molecule? A. H 2 B. HCl C. PH 3 D. AsH 3 (2) 1.4 Which one of the following has the lowest boiling point? A. CH 4 B. CH 3 CH 3 C. CH 3 CH 2 CH 3 D. CH 3 CH 2 CH 2 CH 3 (2) ICG 3 NSC Grade 11

4 1.5 The formula to convert Celsius temperature(t) to Kelvin temperature(t) is: A. T = t 273 B. T = t C. T = t 100 D. T = t (2) 1.6 The pressure of a gas in a closed container is X when the temperature is Y. What will the pressure of the gas in the container be when the temperature is 2Y. A. ½X B. X C. 2X D. 4X (2) 1.7 In which one of the following is the energy required to break the bond(s) between the atoms the highest? A. H 2 B. Cl 2 C. O 2 D. N 2 (2) 1.8 The difference in electro negativity between two elements in a chemical bond is 2. The type of chemical bond is most likely: A. pure covalent. B. ionic. C. polar covalent. D. metallic. (2) 1.9 The electrons in the metallic bond are called: A. valence electrons. B. metalled electrons. C. localised electrons. D. delocalised electrons. (2) 1.10 When a pellet of sodium azide (NaN 3 ) is ignited, a rapid reaction takes place that liberates large amounts of nitrogen gas. This reaction is used in: A. airbags. B. plastic explosives. C. jet fuels. D. rock blasting. (2) [20] TOTAL SECTION A: 20 ICG 4 NSC Grade 11

5 SECTION B (130 MARKS) ANSWER ALL THE QUESTIONS INSTRUCTIONS AND INFORMATION: 1. Answer SECTION B in the ANSWER BOOK 2. The formulae and substitutions must be shown in ALL calculations 3. Round off your answer to TWO decimal places. QUESTION Define a dative covalent bond. (2) 2.2 Water reacts with a proton (H + ), Use Lewis diagrams to write a balanced chemical equation for the reaction that takes place. (5) Give the name of the product formed in Question (1) Name the shape of the product formed in Question (1) Is the O H chemical bond inside the water molecule polar covalent or pure covalent? Motivate your answer by doing and showing the necessary calculations. (4) 2.3 The graph below depicts the boiling points of the group V halides Name the bond or force present between the particles of the hydrides from PH 3 to SbH 3. (1) ICG 5 NSC Grade 11

6 2.3.2 Why do the boiling points increase from PH 3 to SbH 3? (2) Explain briefly the high boiling point of NH 3. (4) [20] QUESTION Answer the following questions about the VSEPR theory: What does the acronym VSEPR stand for? (2) What can VSEPR theory predict? (1) What is the scientific theory that is used to justify the prediction in Question 3.1.2? (2) 3.2 Complete the table below by providing the missing information. Only write down the question number and next to it the missing information. The first row in the table is an example. Number of valence electrons around the central atom The molecule s VSEPR notation The shape of the molecule An example of the molecule 2 AX 2 Linear BeF Tetrahedral AlF Explain why the bond angle in PH 3 (between P H groups) is 107,5 o but that in H 2 O (between O H groups) is 104,5 o. (3) [14] (6) ICG 6 NSC Grade 11

7 QUESTION Research shows that, under certain conditions, real gasses do not obey the relationship between volume and pressure known as Boyle s Law, but show deviations as represented by the sketch graph above. Study the graph and answer the questions below Define Boyle s Law. (2) What physical quantities are represented by the x axis and y axis respectively? (2) Write down which letter A or B in the sketch graph above best represents the relationship for an ideal gas. (1) Explain briefly how you arrived at your answer to Question (2) Explain briefly how the properties of a real gas cause deviation from ideal gas behaviour. (2) 4.2 The pressure in an empty aerosol canister which originally contained an air freshener is 108 kpa at 21 0 C. A boy throws this container of 400 cm 3 into a fire and when the temperature and volume have increased to C and 410 cm 3 respectively, it explodes. What was the pressure inside the canister the moment before it exploded? (5) ICG 7 NSC Grade 11

8 4.3 The pressure gauge on an oxygen gas cylinder which contains 2, oxygen molecules show a reading of 4, kpa. After some of the gas has been used, the gauge shows a pressure of 2, kpa. The temperature and volume do not change during the entire period. Calculate the mass of the oxygen gas that was released. (10) [24] QUESTION 5 Learners investigate the relationship between the pressure and temperature of an enclosed sample of air using the following apparatus: 5.1 What does the meter measure? (1) 5.2 What other two items of equipment, not shown in the diagram, are needed to carry out the investigation? (2) 5.3 Describe briefly how the learners should carry out the investigation. (5) 5.4 Identify the: dependant variable. (1) independent variable. (1) two variables kept constant. (2) ICG 8 NSC Grade 11

9 5.5 The results of their investigation is summarised in the table below: Temperature in 0 C Pressure in kpa Write down the name of the gas law that the learners investigated. (1) Use the values on the table and determine whether the air in the flask obeyed the gas law named in Question (4) [17] QUESTION A compound contains 52,2% carbon, 13,0% hydrogen and 34,8% oxygen Determine the empirical formula of the compound. (10) Determine the molecular formula of the compound if the compound has a molar mass of 92 g.mol -1. (5) 6.2 Two beakers X and Y contain solutions as illustrated below. The contents of X and Y is emptied into container Z. What is the concentration of sodium ions in container Z? (8) [23] ICG 9 NSC Grade 11

10 QUESTION The chemical reaction formula below shows the reaction between iron and oxygen. Fe(s) + O 2 (g) Fe 2 O 3 (s) In a reaction 224 g of iron reacts with 50 g oxygen gas Balance the above chemical equation. (3) Calculate: The number of moles of iron in the reaction. (3) The number of moles of oxygen gas in the reaction. (3) Which reactant is the limiting agent? (1) Give a reason to your answer in Question (2) Calculate the mass of Fe 2 O 3 that forms in this reaction. (4) 7.2 Nitro-glycerine is the main ingredient in explosives such as TNT and dynamite. During an explosion nitro-glycerine decomposes as follows: 4 C 3 H 5 (NO 3 ) 3 (s) 12 CO 2 (g) + 10 H 2 O(g)+ 6 N 2 (g) + O 2 (g) Calculate the total volume of gas released when 100 g of nitroglycerine decomposes at STP. (6) [22] ICG 10 NSC Grade 11

11 QUESTION 8 Study the sketches below illustrating the properties of water and answer the questions follow: 8.1 In Sketch B, 1 and 3 illustrate the menisci of water and mercury inside glass tubes What types of meniscus do water and mercury have? (2) Explain briefly how the meniscus of mercury is formed. (2) What phenomenon is illustrated by tube 2? (1) What problem is caused by the phenomenon named in Question in the walls of some houses? (1) 8.2 What property of water is illustrated by Sketch A? (1) 8.3 Explain briefly how the tight film on which the spider walks is formed. (3) [10] TOTAL SECTION B: 130 GRAND TOTAL: 150 MARKS ICG 11 NSC Grade 11

12 FOR YOUR NOTES: ICG 12 NSC Grade 11

13 GRADE 11 MID-YEAR EXAMINATION PHYSICAL SCIENCES PAPER 2 (CHEMISTRY) ANSWER SHEET Detach from your question paper and insert in your Answer Book. NAME: STUDENT NUMBER: QUESTION A B C D 1.2 A B C D 1.3 A B C D 1.4 A B C D 1.5 A B C D 1.6 A B C D 1.7 A B C D 1.8 A B C D 1.9 A B C D 1.10 A B C D [10 2 = 20] TOTAL SECTION A: 20 ICG 13 NSC Grade 11

14 ICG 14 NSC Grade 11

15 mvphysical Sciences Paper 2 (Chemistry) GRADE 11 DATA FOR PHYSICAL SCIENCES PAPER 2 (CHEMISTRY) TABLE 1: PHYSICAL CONSTANTS NAME SYMBOL VALUE Avogadro s constant N A or/of L 6,02 x mol -1 Universal gas constant R 8,31 J.K -1.mol -1 Molar gas volume at STP V m 22,4 dm 3.mol -1 Standard pressure Standard temperature p θ T θ 1,013 x 10 5 Pa 273 K TABLE 2: FORMULAE pvpvn1122tt1= c = V2pV = nrt c = Mmn = M ICG 15 NSC Grade 11