RVHS_H2_CHEM_P3 Prelim

River Valley High School 9647/03/PRELIM/11 [Turn overPreliminary Examination 2011 RIVER VALLEY HIGH SCHOOL YEAR 6 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS 6 CENTRE NUMBER S INDEX NUMBER H2 CHEMISTRY 9647/03 Paper 3 Free Response 12 September 2011 2 hours Candidates answer on separate paper. Additional Materials: Answer Paper Graph Paper Cover Page Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class, Centre number and index number on all the work you hand in. Write in dark blue or black pen on both sides of paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer any four questions. Begin each question on a fresh sheet of paper. A Data Booklet is provided. Do not write anything on it. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the examination, fasten all your work securely together, with the cover page on top. _______________________________________________________________________________ This document consists of 11 printed pages.

2 River Valley High School 9647/03/PRELIM/11 [Turn overPreliminary Examination 2011 Answer any four questions. 1 Nitrogen is one of the most abundant elements on earth. It is present in many molecules that find applications in chemistry and biology, such as ammonia, haemoglobin and amino acids. (a) During the combustion of ammonia, it reacts to form nitrogen gas and water vapour as seen in the equation below: 4NH3(g) + 3O2(g)  2N2(g) + 6H2O(g) (i) Using relevant data from the Data Booklet , calculate the enthalpy change of the reaction. (ii) Given that the theoretical value of enthalpy change of reaction is 1267 kJ mol-1, explain why the calculated value is different. (iii) State, with reason, the sign of the entropy change of the reaction. Hence, explain if the above reaction is spontaneous. (iv) Rank the four gases of NH 3, O 2, N 2 and H 2O in order of increasing deviation from ideal behaviour. Explain your answer. [8] (b) Haemoglobin is red pigment in blood responsible for carrying oxygen from the lungs to the cell of the body. The molecule consists of a Fe 2+ ion, a porphyrin ring system and a complex protein known as globin. The structure of haemoglobin is given below. (i) Describe the quaternary structure of haemoglobin. (ii) It was found that one molecule of haemoglobin combines with four molecules of oxygen. If 2.00 g of haemoglobin combines with 3.06 cm 3 of oxygen at 37.0 °C and 98.7 kPa, what is the molar mass of haemoglobin? State any assumptions you made in your calculations. (iii) The actual molar mass of haemoglobin is 6.90 x 10 4 g mol-1. Based on your working in (ii), suggest, with r