Ice-water mixture

To find the correct temperature on a thermometer reading 80°C and that shows a reading of — 0.30°C in a melting ice/water mixture and 99.0°C in steam at 760 mm pressure of mercury ... 

Carbazole [86-74-8J M 167.2, m 240-243 , pK <0. Dissolved (60g) in cone H2SO4 (300mL), extracted with three 200mL portions of benzene, then stirred into 1600mL of an ice-water mixture. The ppte was filtered off, washed with a little water, dried, crystd from benzene and then from pyridine/ benzene. [Feldman, Pantages and Orchin J Am Chem Soc 73 4341 795/]. Has also been crystd from EtOH or toluene, sublimed in vacuum, zone-refined, and purified by TLC. 

To an ethanolic solution of sodium ethoxide prepared by addition of 0.46 g (0.02 mole) of freshly cut sodium metal in 100 mL of absolute ethanol was slowly added 5.10 g (0.02 mole) of ethyl 4-nitrobenzylthioacetate 28 with stirring at 5°C. The mixture was refluxed for about 4 to 6 hours until the reaction was complete (monitored by tic). The resultant mixture was allowed to cool to room temperature and then added into an ice-water mixture. The solution was neutralized with slow addition of dilute aqueous hydrochloric acid (10%). The precipitated solid was removed by filtration, washed with water, and recrystallized from a dimethylformamide-ethanol (T.l) mixture yielding 2.10 g (76 %) of 29 as a light brown crystalline solid, mp 227°C ir (nujol) (neat (1710 cm ms m/z Til (NT). Anal. Calcd. For C13H11NO4S C, 56.31 H, 3.97 N, 5.05 S, 11.55. Found C, 56.36 H, 3.95 N, 5.01 S, 11.49. 

After the addition had been completed, the acidic solution containing p-acetylphenyldiazo-nium chloride formed in the above reaction was added dropwise with stirring to a mixture of 530 ml of glacial acetic acid and 530 ml of benzene which had been previously cooled, and the cooled solution saturated with sulfur dioxide and to which had been added 34 g of cupric chloride dihydrate. After the addition had been completed, the reaction mixture was stirred at about 40°C for three hours, and was then poured into 3,000 ml of an ice-water mixture. 

The reaction flask was washed twice with pyridine, and these washings were added to the ice-water mixture. This mixture was kept at about 25°C until the ice had melted, and was then stored at 0°C for one hour. A pale yellow precipitate that formed was collected on a filter, washed with ice-water, and dried in air. 

The graph in Figure 11-37 shows that adding heat to boiling water does not cause the temperature of the water to increase. Instead, the added energy is used to overcome intermolecular attractions as molecules leave the liquid phase and enter the gas phase. Other two-phase systems, such as an ice-water mixture, show similar behavior. 

Heat added to an ice-water mixture melts some of the ice, but the mixture remains at 0 °C. Similarly, when an ice-water mixture in a freezer loses heat to the surroundings, the energy comes from some liquid water freezing, but the mixture remains at 0 °C until all the water has frozen. This behavior can be used to hold a chemical system at a fixed temperature. A temperature of 100 °C can be maintained by a boiling water bath, and an ice bath holds a system at 0 °C. Lower temperatures can be achieved with other substances. Dry ice maintains a temperature of -78 °C a bath of liquid nitrogen has a constant temperature of-196 °C (77 K) and liquid helium, which boils at 4.2 K, is used for research requiring ultracold temperatures. 

The negative sign for the entropy change of the ice/water mixture is consistent with our qualitative view that matter is more dispersed in a liquid than in a solid. The positive sign for the entropy change of the freezer is consistent with heat being absorbed by the freezer, which increases the dispersal of energy. 

C14-0008. Suppose that a mixture of ice and water is placed in a refrigerator that is held at the freezing point of water, exactly 0.0 °C. Calculate A S for the ice-water mixture, A S for the refrigerator, and A Stgtai when 5.00 g of ice forms. Is this process spontaneous Is the reverse process spontaneous ... 

Add enough distilled water to bring the ice-water mixture up to the 200-mL line. 

Stir the ice-water mixture well with the stirring rod. 

Place the beaker on the hot plate, and insert the thermometer into the ice-water mixture. Clamp the thermometer to the ring stand so that the thermometer does not touch the side or bottom of the beaker. 

Turn on the hot plate, and begin heating the ice-water mixture. Stir the ice-water mixture continuously. 

Thinking Critically What was the purpose of the CaCl2 in the ice (Hint What would be the temperature of an ice-water mixture ... 

The resulting rather stiff paste is chilled in an ice-water mixture for 1 hour. The solid is collected on a 15-cm. Buchner funnel and washed with 25-ml. portions of absolute ethyl alcohol until it is white and until the filtrate becomes colorless (100-200 ml. of alcohol is required). The fluffy material, after it is dried in a vacuum desiccator over flake sodium hydroxide, weighs 66 g. (40%). 

In a 2-1. round-bottomed flask are placed, in the order mentioned, 50 g. (1 mole) of 98% sodium cyanide in 100 ml. of water, 58.9 g. (1.1 moles) of ammonium chloride in 140 ml. of lukewarm water (about 35°), and 134 ml. (2 moles) of aqueous ammonia (sp. gr. 0.90). The mixture is shaken while 120 g. (1 mole) of acetophenone in 300 ml. of 95% ethyl alcohol is added. The flask is stoppered with a rubber stopper, which is wired in place (Note 1), and is then immersed in a water bath maintained at 60°. The flask is shaken from time to time, and a homogeneous solution results within half an hour. The reaction mixture is heated for 5 hours at 60°, then well cooled in an ice-water mixture, and poured, with precautions (under a well-ventilated hood), into a 5-1. round-bottomed flask which is immersed up to the neck in an ice-water mixture and which contains 800 ml. of concentrated hydrochloric acid (sp. gr. 1.18-1.19). The reaction flask is rinsed with two 25-ml. portions of water, which are added to the hydrochloric acid solution. The solution of the aminonitrile is satu-... 

If the oil does not crystallize it is cooled in an ice-water mixture until solidification is complete. The solid is returned to the desiccator for complete drying. The desiccator must be evacuated slowly or spattering will take place. 

A. 1,4-Diphenyl-5-amino-l,2,3-triazole. A 500-ml. three-necked flask is equipped with a sealed stirrer, a thermometer well, and a dropping funnel which is protected by a drying tube and has a pressure-equalizing side arm. A mixture of 35.7 g. (0.3 mole) of phenyl azide (Note 1) and 38.6 g. (0.33 mole) of phenylacetonitrile (Note 2) is placed in the flask. The flask is immersed in an ice-water mixture contained in a 1-gal. Thermos flask. After the reaction mixture has cooled to about 2°, a solution of 24.3 g. (0.45 mole) of sodium methoxide (Note 3) in 150 ml. of absolute ethanol is added dropwise during the course of 2 hours. The reaction mixture is then stirred at 2-5° in the ice-water bath for a period of 48 hours (Note 4). After the cooling bath has been removed and the flask allowed to warm spontaneously to room temperature, the mixture is filtered by suction on a sintered glass funnel, and the col-... 

After the reaction mixture has been cooled, the excess phosphorus oxychloride is distilled under reduced pressure (80-100 mm.) (0.5-1.0 hour). Near the end of the distillation the product begins to sublime into the still head. The residual dark-brown oil is poured with stirring into an 800-ml. beaker containing 280-300 g. of crushed ice (Notes 3 and 4). The volume of the ice-water mixture is brought to 600 ml. and allowed to stand at 5° overnight. The crude light-brown product is filtered by suction and washed with water. 

N-(3-ethvnvlphenvl)maleimide—N-(3-ethynylphenyl)maleamic acid (21.5 g 0.100 mol), anhydrous sodium acetate (6.0 g 0.0731 mol), and 175 mL of acetic anhydride (1.86 mol) were stirred together and heated at 50°C for 3 hr. The reaction mixture was cooled to room temperature and filtered. The filtrate was precipitated in an ice-water mixture to yield an impure product. This product was dissolved in hot ethanol and recrystallized by addition of cold water to yield 5.3 g (27% of theory) of a fine yellow powder, m.p. 130-131°C. 

A thermocouple is a junction of two metals that produces a voltage proportional to temperature and is therefore a device for measuring temperature. A thermocouple can be calibrated with the use of known temperatures, such as the freezing point of water (slushy ice-water mixture) or temperatures known because they are measured with a calibrated thermometer. 

These three tubes contain a mixture of N02 g and N204(g). The tube on the left is in an ice-water mixture. The centre tube is at room temperature. The tube on the right is in boiling water. Given that N02 g is brown, can you explain the shift in equilibrium Think about Le Chatelier s principle and the enthalpy of the reaction between the two gases. 

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