Cm3 Of Water Research Articles

Kinetic studies of the formation of copper(I) in water + acetonitrile mixtures at 25 °C from the reversible reaction Cu2++ Cu0⇌ 2Cu+

The rate of the forward reaction of the reversible reaction Cu2++ Cu0⇌2Cu+ has been measured at 25 °C in 150 cm3 of water + acetonitrile (H2O + AN) mixtures containing 5, 10, 20 and 40%(v/v) acetonitrile (AN) together with 0.032, 0.064, 0.16 and 0.32 mol dm–3 copper sulphate, 0.070 mol dm–3 H2SO4 and 1, 4 and 8 g of copper crystals 2–30 µm in size. The rate of the reaction is strongly influenced by the concentrations of copper sulphate and AN and by the amount and particle size of the copper crystals. The rate of the reaction in an atmosphere of nitrogen is not affected by up to 0.47 mol dm–3 H2SO4.The reaction under investigation is reasonably fast and in most cases goes almost to completion in 3–5 h. By reversing the reaction, the backward reaction becomes faster than the forward reaction and pure copper powder starts separating out from the solution. The present investigation is thus very useful for developing a cheap and quick method for the recovery of copper from crude samples.

The Effect of Water Supply on the Growth of lzmir, Palotina and Amarelinho Tobaccos

Abstract The Oriental tobacco variety Izmir has been grown in sand culture in a greenhouse under various degrees of water stress. Plants given 400 cm3 of water (or nutrient solution) twice a week produced leaves of approximately the same size as field-grown Izmir tobacco, but they were somewhat taller. Plants given 25 cm3 or less of water twice a week died, and those given more than 400 cm3 of water twice a week grew larger than field-grown Izmir tobacco. At 49 days after transplanting, the total leaf area per plant was approximately proportional to the amount of water supplied, at least in the range 100-1600 cm3. In a second water stress experiment, the growth patterns of the varieties Amarelinho and Palotina, which are not normally grown in conditions of water stress, were found to be different from that of Izmir. Izmir was more tolerant of water stress than the other two varieties, in that complete (but small) plants developed in a shorter time.

Alkalimetric determination of halogeno or carboxylato groups in their triaryl- or trialkylantimony (V) derivatives

Halogeno or carboxylato groups in their triaryl- or trialkylantimony (V) derivatives have been determined by alkalimetry after their hydrolysis. The standard analytical process is as follows. About 0.2 mmol(70 150 mg) of the sample is taken into a 200 cm3 beaker, and is dissolved into 20 cm3 of acetonitrile. The mixture is boiled if the sample is hardly soluble. After the complete dissolution, it is diluted with 20 cm3 of water, and is kept for several min. The solution is then titrated with 0.1 M sodium hydroxide aqueous solution. Acetone, N, N-dimethylforrnamide, tetrahydrofuran, and dimethylsulfoxide can also be used in place of acetonitrile (N, N-dimethylforma mide solution should not be boiled). Satisfactory results could be obtained for 13 organoantimony compounds, such as dibromotriphenylantimony (V), diacetatotriphenylantimony (V), bis (benzoato) tris (p tolyl) antimony (V), dibromotrimethylantimony (V) etc. (The samples used were over 99.7% in their purity estimated from their carbon analyses). This method is conveniently applicable to check the composition of the samples of these compounds.

Rice Seedlings Germinated in Water with Normal and Impeded Environmental Gas Exchange

One hundred 'Pyrex' beakers (250-ml with a spout or 400-ml tall-form without a spout) were marked at the 170-cm3 level and were filled to this point with distilled water. The depth of 170 cm3 of water was c. 5*5 cm in either type of beaker, this depth being the same as that employed when broadcasting rice seeds in fields in the United States (Grist 1965). Ten unhulled, unwashed, and unsterilized rice seeds without any fungicidal dressing (Oryza sativa, var. Hokkaido-Carny) were dropped into each of ninety beakers. Only those seeds which sank quickly to the bottom of the beakers when dropped into the water were used. Any seeds that floated after repeated immersion in the water were discarded and replaced with seeds that settled rapidly to the bottom of the beakers. No attempt was made to remove any gas bubbles that became trapped in the hulls of the seeds as long as the seeds settled quickly on the bottom of the vessels. Seeds were not put into the remaining ten beakers. The surface of the water in thirty beakers with seeds and in the ten beakers without seeds was overlayed with 30 cm3 of olive oil per beaker (British Pharmacopoeia Standard). Ten beakers were overlayed with 3 cm3 of olive oil, ten beakers with 1 cm3 of olive oil, and ten beakers with 30 cm3 of liquid paraffin (light grade) per beaker. The surface of the water in the remaining thirty beakers was left with a normal air-water interface (no oil overlay). All beakers of all treatments were covered with thin watch-glasses (7.5 cm diameter) to prevent debris from falling into the vessels and to reduce the evaporation of water from the beakers without an oil overlay. The water level in the beakers without the oil overlay was checked daily and was maintained at the 170-cm3 level by adding distilled water whenever necessary. The 30-cm3 olive-oil overlay was removed from one-half of all treatments containing seeds on the fourteenth day and from the remaining half of these treatments on the twenty-fourth day after the start of the investigation. Oxygen electrode measurements of the water of all treatments were made on the fourteenth and twenty-fourth day just prior to the removal of the 30-cm3 olive oil overlay. The oil layer was removed by filling the

Detachment of Soil Aggregates by Simulated Rainfall

AbstractSharpsburg silty clay loam was separated into 11 aggregate fractions with the following diameters: 9,250–4,760µ, 4,760–3,360µ, + … +, 297–210µ, and <210µ. Krilium solution was added to half of each aggregate fraction to make the aggregates more water‐stable. The aggregate fractions were packed into splash‐cups and exposed to simulated rainfall intensities from 2 to 12 cm/hr. Raindrops were 5.1 mm in diameter and fell 11.33 m onto the surface of soil materials. Splash of soil particles and aggregates was caught, oven‐dried, and weighed.The amount of detachment of aggregates was linearly related to the rainfall intensity.Detachment of non‐treated aggregates exposed to rainfall increased from 76 mg of particles per cm3 of water to a maximum amount of 172 mg/cm3 as the aggregate diameters decreased from 9,250–4,760µ to 2,360–1,680µ. Then, the amount of detachment decreased with decreasing diameter to aggregate to 78 mg/cm3 for aggregates < 210µ diameter.The addition of Krilium to aggregates reduced the amount of detachment of aggregates >420µ in diameter exposed to simulated rainfall. The amount of splash increased with decreasing diameter of Krilium treated aggregates until 297–210µ diameter was reached (138 mg/cm3), then it decreased (101 mg/cm3) for aggregates < 210µ diameter.

Detachment of Soil Particles in Simulated Rainfall

AbstractSoil materials were fractionated into 20 separates ranging from 4,760µ to < 2µ in diameter. These separates were packed into splash‐cups and exposed to simulated rainfall intensities of 2 to 12 cm/hr. Raindrops were 5.1 mm in diameter and fell 11.33 m onto the surface of soil materials. Soil particles detached from the surface by the raindrops were oven‐dried and weighted.The amount of detached soil particles from surfaces of all separates was linearly related to simulated rainfall intensity. Linearity was significant at the 0.01 level of probability, except for the coarsest and finest separates. Slope of the line is used to characterize the susceptibility of soil materials to detachment from the surface by raindrops. The slope is measured as milligrams of particles per cm3 of water hitting the surface of soil materials.Detachment of soil particles exposed to simulated rainfall increased from 2.2 mg/cm3 of water for separates 4,760–3,360µ in diameter to a maximum amount of 288 mg/cm3 of water for separates 210–149µ and 149–105µ in diameter. Then, the amount of detached particles decreased with decreasing diameter of particles. Detachment for < 2µ diameter particles was 11 mg/cm3 of water.High‐speed movies showed that splash of raindrops from surfaces of separates > 105µ in diameter consisted of much smaller water drops than from separates < 105µ in diameter. Splash from the surfaces of separates < 105µ in diameter exhibited a crown effect and then broke into smaller drops.

Een eenvoudige methode voor het afscheiden van aaltjes uit grond

For separating eelworms from soil a sample of 500 g is weighted out and stirred with about 700 cm3 of water in a beaker.