Edexcel Jun 2013 (R) Paper 2 Q23

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SECTION C Answer ALL the questions. Write your answers in the spaces provided. 23 Nanorockets have generated a lot of excitement due to their potential uses in the medicinal field, such as in the delivery of drugs around the body. Some bacteria have the ability to move at speeds of 100 times their body length per second. Scientists in one study made nanorockets that reached speeds of up to 200 times their length per second. These scientists made their rockets on a nano scale (109) from nanotubes with platinum coated on the inside as a catalyst. The fuel used to power these tiny rockets was hydrogen peroxide, H2O2, which forms water and oxygen gas when undergoing decomposition. Other forms of nanotechnology are already being used. For example, some sun creams use nanoparticles of titanium(IV) oxide which form an invisible protective layer against UV radiation. (a) Write an equation for the catalytic decomposition of hydrogen peroxide. State symbols are not required. (b) Draw a dot and cross diagram to show the electronic configuration of the oxygen gas produced in the breakdown of the hydrogen peroxide (only outer electrons should be shown). (c) Suggest a dot and cross diagram for the hydrogen peroxide molecule in which each oxygen atom is covalently bonded to one hydrogen atom (only outer electrons should be shown). (1) (1) (2) 16 *P42983A01620*<br /> *(d) The bond angles in hydrogen peroxide are similar to those in a water molecule. Suggest a bond angle for hydrogen peroxide and reasons for your value. (3) Bond AngleReasons(e) In the future, the aim is to develop a nanorocket that can use a fuel such as glucose rather than hydrogen peroxide. Suggest an advantage of using glucose and a disadvantage of using hydrogen peroxide. (2) Glucose advantageHydrogen peroxide disadvantage(f) The boiling temperature of hydrogen peroxide is relatively high, about 150qC, for such a small molecule. Explain fully why this is the case. (2)*P42983A01720* 17 Turn over<br /> *(g) It is suggested that hydrogen peroxide is a polar liquid. Describe how you might carry out an experiment to test whether a liquid is polar. (3)*(h) The speed of the nanorockets is controlled by the rate of decomposition of hydrogen peroxide. The speed at the body temperature of 37qC is faster than under normal laboratory conditions. Draw Maxwell-Boltzmann distribution curves on the axes below. Label your diagram and use it to explain why the increase in the speed of the rockets occurred. (4)18 *P42983A01820*<br /> (i) The scientists used platinum in their nanorockets. Explain the catalytic role of the platinum in the reaction. (2)(j) Nanotubes can be made from carbon. These carbon nanotubes can be good electrical conductors in a similar way to graphite. Explain why they are able to conduct electricity. (2)(k) Some scientists are concerned that the use of nanoparticles in cosmetic products, such as sun cream, could pose a health hazard. Suggest why this might be the case. (1)(Total for Question 23 = 23 marks) TOTAL FOR SECTION C = 23 MARKS TOTAL FOR PAPER = 80 MARKS *P42983A01920* 19<br />

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