4 11141.03 Question 1 Requirements • Gas jar with diameter 4–6 cm, capacity at least 200 ml, mass less than 300 g • Half metre rule • Vernier callipers • Electronic balance capable of reading up to 500 g to nearest 1 g or 0.1 g • 250 ml beaker • 150 ml salt water solution (approx. 1.1 g cm–3) • 250 ml graduated cylinder (teacher use only) • Insulating tape Preparation Place some insulating tape over the scale of the beaker. Use the graduated cylinder to measure 150 ml of the salt solution and put it into the gas jar. Place the gas jar, half metre rule, vernier callipers, empty beaker and electronic balance on the bench at workstation. Ensure all instruments are zeroed as appropriate. Action at changeover Pour the 150 ml salt solution into the gas jar. Place apparatus as at start of experiment with all instruments zeroed. Question 2 Requirements • Thermistor EPCOS B57164K471J or similar (KED471). RS 191–2229 • 1.5 V D cell • Digital milliammeter 0–20 mA to 0.01 mA • Digital voltmeter 0–20 V to 0.01 V • Connecting leads with 5 mm plugs at each end × 6 • 250 ml beaker • Water at room temperature • Crushed ice • Retort stand and clamp • Switch • Method of clamping the thermistor into retort stand, e.g. component holder with crocodile clips. • Dessert spoon/soup spoon • Thermometer with range -10°C to 110°C 5 11141.03 Preparation Set up the circuit shown in Fig 2.1. A V Fig. 2.1 Attach the thermistor to the crocodile clips of a component holder. Clamp the component holder and thermometer in a retort stand and place in a beaker of water at room temperature as shown in Fig. 2.2(a) and (b). Fig. 2.2(a) Fig. 2.2(b) Source: Chief Examiner Source: Chief Examiner Action at Changeover Replace the iced water in the beaker with water at room temperature. To do this slide the retort stand towards the edge of the bench so that the beaker can be lowered off the edge of the bench as shown in Fig 2.3. Fig 2.3 Source: Chief Examiner