BOYLE S / CHARLES LAW APPARATUS - 1m long

Transcription

1 BOYLE S / CHARLES LAW APPARATUS - 1m long Cat: MF (combination Boyle s and Charles without mercury) DESCRIPTION: The IEC Boyle's & Charles Law apparatus is a high quality instrument designed to perform the standard experiments relating gas volume to gas pressure. The unit requires approx. 150gm of distilled mercury (not supplied in the kit). By applying several additional components, the instrument can be converted from Boyle s Law function to be the Constant Volume Thermometer (Charles Law). MF combination Boyle s & Charles Physical size: 250x140x1140mm LxWxH Weight: 1.7 kg

2 NOTE: When filling units with mercury, do not knock over or invert the unit or mercury spillage will occur. Mercury is poisonous and should not be touched. In the case of spillage, follow correct chemical procedures. During storage and to prevent mercury spillage during handling, a rubber stopper may be fitted to the mouth of the open glass tube. Instructions for assembly and filling with Mercury are provided on this sheet. KIT COMPONENTS LIST: FOR BOYLE S LAW: 1 pce LONG ALUMINIUM RAIL COMPLETE WITH 1m SCALE. 1 pce STEEL BASE PLATE. 1 pkt SCREWS, WASHERS & NUTS FOR ASSEMBLY AND FOR SLIDERS. 2 pcs ALUMINIUM SLIDERS WITH CLIPS FOR GLASS TUBES. 1 pce GLASS TUBE WITH OPEN END. 1 pce GLASS TUBE WITH CLOSED END. 1 pce RUBBER HOSE TO JOIN THE GLASS TUBES, 1M LONG x 3mm BORE. 1 pce INSTRUCTION SHEET with final assembly sketches. ADDITIONAL PARTS TO CONVERT THE INSTRUMENT TO CHARLES LAW: 1pce GLASS TUBE WITH REFERENCE MARK AND BENT LEG. 1pce THIN WALLED GLASS BULB 50mm DIAMETER. 1pce RUBBER JOINER PIECE. 1pce L SHAPED WIRE SUPPORT LEG FOR GLASS TUBES. 1pce RUBBER LOOP TO HOLD GLASS TUBE TO L SHAPED SUPPORT. 1pce WIRE FRAME FOR SUPPORTING A BEAKER. 1pce GLASS BEAKER, 400ml ASSEMBLY INSTRUCTIONS - BOYLE'S LAW: Unpack containers and check all parts are correct. Insert the two large headed screws into the two aluminium slider plates with the screw head on the same side of the plate as the spring clips. Place the large washer over the thread and fit the wing nut to the thread. Do not tighten the wing nuts. Lay the long aluminium rail on the table with the plastic end cap at the far end and fit the two aluminium sliders to the rail by sliding the large screw heads into the slots provided in the rail. The square shape on the screw will slide in the slot in the rail and will prevent the screw from rotating. Be sure that the spring clips are on the same side of the rail as the metric scale. Move the sliders along the rail to about the midposition and tighten the wing nuts gently. Attach the steel base plate to the end of the long rail with the 4 small screws provided. If the plastic scale protection strip protrudes from the end of the rail, cut the excess with scissors or a sharp knife. Tighten the screws firmly and stand the unit upright on the table.

3 Take the two glass tubes (1x open end and 1x closed) and fit the rubber hose firmly to the small end of the OPEN tube ONLY. To make the rubber fit more easily, wet the end of the glass. Do not wet the inside of the glass tube or the rubber hose. Take this open end glass tube and clip it into the spring clips of the right hand slider so that the rubber is about level with the bottom edge of the slider. IMPORTANT:: Take the free end of the RUBBER HOSE and temporarily clip it into the spring clips of the left hand slider. Then adjust this slider so that the open end of the rubber hose is about level with the UPPER end of the open glass tube clipped to the right hand slider. FILLING WITH MERCURY FOR BOYLE S LAW: IMPORTANT NOTE: Mercury is an expensive, dangerous and very poisonous substance. Take care when filling the unit so that mercury is not spilled. Avoid contact with the skin and follow proper procedures for clearing a spillage. At this time, the rubber hose is clipped into the left hand slider and the open ended glass tube is clipped into the right hand slider. The open mouth of the glass tube should be about level with the open mouth of the rubber hose. Take distilled mercury in a plastic dropper bottle and, very carefully, squeeze the mercury into the right hand glass tube and the rubber hose until the level is visible about two thirds of the way up the glass tube. Wriggle the rubber hose gently with the hand to permit any trapped air to rise into the glass tube and escape. Carefully lower the left hand slider with the rubber hose until the mercury is JUST visible approaching the end of the hose. DO NOT ALLOW THE MERCURY TO ESCAPE OUT THE END OF THE HOSE. Fit the small end of the closed glass tube into the end of the rubber hose. Remove the hose from the clips and clip the closed glass tube into the clips. Adjust the two sliders so they are opposite each other and add mercury to the open tube until it is again about two thirds full. Mercury should be seen beginning to enter the closed tube. As the open tube is raised and lowered by its slider, the air in the closed tube is compressed and the pressure rises in the closed tube. Use the vertical scale to measure the air volume change and the pressure (difference in height of the two mercury levels). Finally, transfer a little air from the closed tube to the open tube so the mercury is about 25mm up the closed tube when the sliders are level. This can be done by unclipping and inverting the closed tube so that a little air runs backwards through the mercury to the open tube. NOTE: When filled with mercury, do not knock over or invert the unit or mercury spillage will occur. During storage only, a rubber stopper fitted to the open glass tube may prevent spillage.

4 BOYLE S LAW CALCULATIONS: Boyle s Law states that gas Pressure x Volume = a constant (k) PV=k or V=k/P Therefore, volume varies in proportion to the inverse of the pressure. Thus a graph of gas volume directly to pressure will be a curve but the graph of gas volume (Y axis) to the inverse of the pressure (X axis) should be a straight line with a slope of k. Remember that air pressure around us already is pressurised to 100kPa (one atmospheric pressure), therefore any reading must have 100kPa added to it to be the true gas pressure. The added pressure on the air is created by the difference in height of the mercury columns. When the mercury levels are exactly level, the added air pressure is zero and the air is at standard atmospheric pressure (actually 100kPa). Move the mercury in the open ended glass tube upwards to exert pressure on the air. Take 6 or 8 different volume readings at different column heights. Plot a graph of air column length (Y axis) to inverse of air pressure (X axis). The graph of the gas volume plotted against the inverse of the total gas pressure should be a straight line and should prove the linear relationship between volume and the inverse of pressure as stated in 'Boyle's Law' of gases. The slope of the line (dy/dx) should be the value of the constant k. A different approach: Boyle s law states that V 1 P 1 =V 2 P 2 =k, so therefore V 1 /V 2 =P 2 /P 1. Take two different pressures (add the 100kPa initial atmospheric pressure in each case) and take the two corresponding volumes or lengths of air columns. See if the law is true. INSTRUCTIONS FOR CONVERSION FROM BOYLE S TO CHARLES LAW: Remove the mercury from the Boyle s Law. Raise the open glass tube 150mm higher than the closed tube, remove the open glass tube from its spring clips and invert it into a clean beaker to collect mercury. Wriggle the hose to collect all the mercury. When mercury stops flowing, refit the open glass tube into the clips and, if some mercury is remaining in the closed glass tube, tap with the finger so that all traces of the mercury falls into the empty hose. TAKE PROPER PRECAUTIONS. MERCURY IS POISONOUS. Remove the closed glass tube from the clips and carefully remove the hose from the end of the tube. Fit the bent glass tube (from Charles Law kit) to the hose and fit the tube into the clips. Fit the two wire legs of the beaker support wire frame UPWARDS vertically into the longitudinal holes in the face of the aluminium slider. The legs will wedge securely into place and this wire frame will support a glass beaker that carries hot water to heat up the air inside the glass ball (sometimes called Jolly bulb ). Fit the short leg of the L shaped wire support DOWNWARDS into the front longitudinal holes in the slider so that the long leg stands out and pivots horizontally.

5 With the two glass tubes side by side, pour the mercury into the open glass tube so that the mercury reaches the reference mark on the glass tube with the bent leg. Fit the rubber loop on the support wire and pass the leg of the glass 'Jolly bulb' through the loop and join it to the bent leg with the rubber joiner piece. At this time the horizontal glass tubes joined by the short rubber joiner should be firmly attached to the L shaped wire leg for strength and support. Place a beaker of hot water on the support frame under the glass ball and immerse the ball into the water. Soak the glass bulb in the hot water so that the air pressure rises and the mercury is pushed down from the reference mark. Then raise the open glass tube so that the mercury returns exactly to the graduated line (the original air volume). Measure the water temperature and calculate the pressure applied by the mercury to compress the hot air back to its original volume. CHARLES LAW CONVERSION Physical size: 250x140x1140mm LxWxH Weight: 1.7kg. Designed and manufactured in Australia

6 ASSEMBLY DIAGRAMS CHARLES' LAW OR CONSTANT VOLUME THERMOMETER BOYLE'S LAW ALUMINIUM RAIL AND SCALE RUBBER JOINER PIECE 'L' SHAPED WIRE SUPPORT RUBBER LOOP THIN WALL GLASS BULB OPEN END GLASS TUBE CLOSED END GLASS TUBE OPEN END GLASS TUBE BEAKER FOR HOT WATER CONSTANT VOLUME GRADUATION MARK SLIDER WITH CLIPS WIRE FRAME TO SUPPORT BEAKER RUBBER HOSE BASE PLATE