Beaker experiment

Think of a beaker containing saturated potassium iodide solution, with undissolved (solid) at the bottom of the beaker. Experiments showthat although the con-... 

Your aim is to generate the largest range of possible concentrations only using combinations of, b2, and b3. You also wish to determine the exact set of beaker experiments that will allow the company to formulate these recipes (if at all). It is your task to carry out the experiments and report back to your boss. How should we go about determining which formulations can be formed ... 

The geometric perspective of a system is an important aspect of AR theory, for it allows us to utilize the fundamental concepts of concentration vectors, mixing, and convex hulls. In Chapter 3, we will return to the BTX beaker experiment and use the graphical concepts described in this chapter to improve the maximum toluene concentration (larger than that obtained in Chapter 1). 

In Chapter 3, we returned to the BTX beaker experiment and used the ideas of mixing and convex hulls from Chapter 2 to improve the maximum concentration of toluene. This chapter also introduced the idea of a candidate AR specific to the system of interest. The AR for the BTX system was revealed as the limiting case of infinitely many batch mixing and reaction experiments, which were conducted in a serial fashion. Chapter 3 also introduced a number of necessary conditions of the AR. Since mixing is a linear process, the AR must be a closed, compact, and convex set of points in concentration space that is formed by the convex hull of all achievable points. 

Optional experiment. When all the air has been displaced, collect a test-tube of the gas over water (by appropriate inclination of the end of the delivery tube beneath the mouth of a test-tube filled with water and supported in a beaker of water). Observe the colour and odour of the gas. Ignite the test-tube of gas, and note the luminosity of the flame and the amount of carbon deposited. Pure acetylene is almost odourless the characteristic odour observed is due to traces of hydrides of phosphorus, arsenic and sulphur. 

With the permission of your instructor, carry out the following experiment. In a beaker, mix equal volumes of 0.001 M NH4SCN and 0.001 M FeCE (the latter solution must be acidified with concentrated HNO3 at a ratio of 4 drops/L to prevent the precipitation of Fe(OH)3). Divide solution in half, and add solid KNO3 to one portion at a ratio of 4 g per 100 mL. Compare the colors of the two solutions (see Color Plate 3), and explain why they are different. The relevant reaction is... 

If we were required to pack beads in a beaker, we know from experience that by jostling the container we could achieve some compaction or decrease in free volume. In fact, we can picture the flow of a huge array of beads through a pipe by considering the beaker as a volume element in that pipe. By vibration, the beads are jostled downward that is, the holes work their way to the top. 

An idea of the possibilities is given by the old high-school chemistry experiment with sulphur crystals ("flowers of sulphur"). A 10 ml beaker is warmed up on a hot plate and some sulphur is added to it. As soon as the sulphur has melted the beaker is removed from the heater and allowed to cool slowly on the bench. The sulphur will... 

Write the equation for the reaction which took place in Experiment 8, Part II. What was the residue you obtained on evaporation of the solution in beaker number 2 ... 

In the combustion reaction as carried out in the calorimeter of Figure 7-2, the volume of the system is kept constant and pressure may change because the reaction chamber is sealed. In the laboratory experiments you have conducted, you kept the pressure constant by leaving the system open to the surroundings. In such an experiment, the volume may change. There is a small difference between these two types of measurements. The difference arises from the energy used when a system expands against the pressure of the atmosphere. In a constant volume calorimeter, there is no such expansion hence, this contribution to the reaction heat is not present. Experiments show that this difference is usually small. However, the symbol AH represents the heat effect that accompanies a chemical reaction carried out at constant pressure—the condition we usually have when the reaction occurs in an open beaker. 

The moles of silver deposited per mole of copper dissolved are the same whether reaction (J) is carried out in an electrochemical cell or in a single beaker, as in Experiment 7. If, in the cell, electrons are transferred from copper metal (forming Cu+2) to silver ion (forming metallic silver), then electrons must have been transferred from copper metal to silver ion in Experiment 7. 

Thus, Experiment 7 involved the same oxidation-reduction reaction but the electron transfer must have occurred locally between individual copper atoms (in the metal) and individual silver ions (in the solution near the metal surface). This local transfer replaces the wire middleman in the cell, which carries electrons from one beaker (where they are released by copper) to the other (where they are accepted by silver ions). 

Prepare 250 mL of 0.02 M potassium dichromate solution and an equal volume of ca 0.1 M ammonium iron(II) sulphate solution the latter must contain sufficient dilute sulphuric acid to produce a clear solution, and the exact weight of ammonium iron(II) sulphate employed should be noted. Place 25 mL of the ammonium iron(II) sulphate solution in the beaker, add 25 mL of ca 2.5M sulphuric acid and 50 mL of water. Charge the burette with the 0.02 M potassium dichromate solution, and add a capillary extension tube. Use a bright platinum electrode as indicator electrode and an S.C.E. reference electrode. Set the stirrer in motion. Proceed with the titration as directed in Experiment 1. After each addition of the dichromate solution measure the e.m.f. of the cell. Determine the end point (1) from the potential-volume curve and (2) by the derivative method. Calculate the molarity of the ammonium iron(II) sulphate solution, and compare this with the value calculated from the actual weight of solid employed in preparing the solution. 

Prepare an approximately 0.1 M silver nitrate solution. Place 0.1169 g of dry sodium chloride in the beaker, add 100 mL of water, and stir until dissolved. Use a silver wire electrode (or a silver-plated platinum wire), and a silver-silver chloride or a saturated calomel reference electrode separated from the solution by a potassium nitrate-agar bridge (see below). Titrate the sodium chloride solution with the silver nitrate solution following the general procedure described in Experiment 1 it is important to have efficient stirring and to wait long enough after each addition of titrant for the e.m.f. to become steady. Continue the titration 5 mL beyond the end point. Determine the end point and thence the molarity of the silver nitrate solution. 

The following experimental details apply both to the determination of tungsten with bromine as internal standard, and to the experiments of Table 7-2. The solutions filled a 3-ml container made by sectioning a 10-ml beaker. To prevent" evaporation and to maintain a fixed distance between x-ray tube window and sample surface, the beaker-section was covered with Mylar film, 0.0025 cm thick, placed in a plastic sample holder and pressed firmly against the sample drawer. The Mylar film attenuated the x-rays uniformly enough so as not to affect the precision of the results. 

FIGURE 8.31 An experiment to illustrate osmosis. Initially, the tube contained a sucrose solution and the beaker contained pure water the initial heights of the two liquids were the same. At the stage shown here, water has passed into the solution through the membrane by osmosis, and the level of solution in the tube has risen above that of the pure water. The large inset shows the molecules in the pure solvent (below the membrane) tending to join those in the solution (above the membrane) because the presence of solute molecules there has led to increased disorder. The small inset shows just the solute molecules the yellow arrow shows the direction of flow of solvent molecules. 

Two beakers, one containing 0.010 m NaCl (aq) and the other containing pure water, are placed inside a bell jar and sealed. The beakers are left until the water vapor has come to equilibrium with any liquid in the container. The levels of the liquid in each beaker at the beginning of the experiment are the... 

The solid polymer tends to stick to glass for this reason, it is preferable to employ a metal beaker for the experiment. 

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