The thermodynamics of binary liquid mixtures of compounds containing multiple bonds.
- Authors: Baxter, Rodney Charles
- Date: 1989
- Subjects: Solution (Chemistry)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4531 , http://hdl.handle.net/10962/d1016079
- Description: Excess thermodynamic properties have been determined for several binary liquid mixtures with the aim of testing various thermodynamic theories and postulates. Excess molar enthalpies, HEm, have been determined using an LKB flow microcalorimeter and excess molar volumes, VEm, have been determined using an Anton Paar vibrating tube densitometer. The activity coefficients at infinite dilution ƴ∞₁₃, have been determined using an atmospheric pressure gas-liquid chromatograph. The excess molar enthalpies and the excess molar volumes have been measured at 298.15 K for systems involving the bicyclic compounds decahydronaphthalene (decalin), 1,2,3,4-tetrahydronaphthalene (tetralin), bicyclohexyl, or cyclohexylbenzene mixed with 1- hexene, 1-hexyne, 1-heptene, 1-heptyne, cyclohexene, 1,3-cyclohexadiene, 1,4- cyclohexadiene, or benzene. These excess properties have also been measured for systems where the bicyclic compound has been replaced with benzene, cyclohexane or n-hexane. The results show defmite trends related to the size, shape, and the degree of unsaturation of the component molecules. The Flory theory has been used to predict excess molar enthalpies and excess molar volumes for {(a bicyclic compound or benzene or cyclohexane or n-hexane) +(an n-alkane or a 1-alkene or a 1-alkyne or a cycloalkane or cyclohexene or a cycloalkadiene or benzene)}. The one parameter equations offer reasonably good correlations between the predicted and the experimental results. More insight into the origins of the contnbutions to the excess thermodynamic properties for these systems has been gained by considering the approximate equations of Patterson and co-workers, which separate the interactional and the free volume contributions to the excess molar enthalpy and the excess molar volume. The one parameter equations have adequately rationalized a good deal of the observed behaviour for HEm and VEm. The theory of Liebermann and co-workers, which does not employ any adjustable parameters, has not been as successful at predicting the excess thermodynamic properties for the above systems. The activity coefficients at infinite dilution have been measured at 278.15 K, 288.15 K and 298.15 K for n-bexane, 1-bexene, 1-hexyne, n-heptane, 1-heptene, 1-heptyne, cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzene, in decalin, tetralin, bicyclohexyl, and cyclohexylbenzene. Solvent losses from the column have been accounted for by an extrapolation procedure. The activity coefficient results together with the HEm and VEm values have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution. The partial molar excess properties at infinite dilution for decalin mixtures are similar to those for bicyclohexyl mixtures. There is also a similarity between the properties of the tetralin mixtures and the cyclohexylbenzene mixtures. The cycloalkadienes, benzene and the 1-alkynes exhibit a strong dissociation effect on being mixed with the saturated solvents, decalin and bicyclohexyl, but associate strongly with tetralin and with cyclohexylbenzene. The Flory theory bas been used to predict activity coefficients at infinite dilution from the experimentally determined HEm results for { (n-bexane or 1-hexene or 1-hexyne or naheptane or 1-heptene or 1-beptyne) + (a bicyclic compound)}. The theory is much better at predicting values for mixtures where both components are either saturated molecules or are unsaturated molecules than for {saturated + unsaturated} mixtures.
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Achievement motivation in a group of educated Blacks in the mining industry and its implications on job performance
- Authors: Jamotte, Ann
- Date: 1980
- Subjects: Employee motivation -- South Africa Achievement motivation -- South Africa Black people -- Employment -- South Africa -- Psychological aspects Black people -- South Africa -- Personnel management
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3140 , http://hdl.handle.net/10962/d1006980
- Description: Summary: The central purpose of this study was to establish whether there is a positive relationship between a high achievement motive (as measured by the Thematic Apperception Test, using the Arnold's scoring system) in Blacks and Good Job Performance (as measured by good merit and supervisory ratings). Factors taken into consideration in the study were: (i)level of urbanization (ii)resistance to change (iii)job satisfaction. An alternative method of scoring the T.A.T. (McClelland) was compared with the Arnold System. A novel T.A.T. was designed with pictures with which the Blacks could easily identify, so that the writing of stories was facilitated. The level of urbanization and resistance to change were measured on the Urban- Rural Scale. Job satisfaction was measured by means of the Job Satisfaction Index. The measures of job performance were obtained by means of 'man specifications' and merit ratings. The Achievement Motivation Score was found to be significantly positively correlated at the ,05 level with job performance ratings, but a predictive study would have to be carried out before it can be accepted as predictive of job performance. Level of urbanization had no significant effect on the achievement, motivation scorer (Arnold System) whereas 'the 'Resistance to Change' factor was found to be significantly negatively correlated at the ,05 level with the achievement motivation scores (Arnold). 'Too little information was available to establish the relationship between high achievement motivation scores (Arnold), low job performance ratings and low job satisfaction scores. No significant correlations was obtained between the McClelland scores on the T.A.T., and the Arnold scores as well as between the McClelland scores on the T.A.T. and job performance ratings. The T.A.T., using the Arnold scoring system, proved to be a reliable test (both test - retest and inter - scorer reliabilities This study showed that the T.A.T. has strong possibilities of playing a large role in the selection of Blacks for higher level jobs in industry.
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The meaning of becoming and being a member of a small and structured religious group
- Authors: Stones, Christopher R
- Date: 1980
- Subjects: Religious communities -- South Africa Jesus People -- South Africa -- Johannesburg Hare Krishnas -- South Africa -- Johannesburg Divine Light Mission Seminarians -- South Africa -- Pretoria Catholic theological seminaries -- South Africa Phenomenological psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3101 , http://hdl.handle.net/10962/d1004381
- Description: The concern of this investigation is with the meaning of becoming as well as being a member of one of four specific small and structured religious communities. Three of these religious groups - the Jesus People, the Hare Krishna Devotees and the Maharaj Ji Premies - are considered to be nonconformist in terms of the life-style, value-system and theology each adopts within the mainstream social and theological ethos, while the fourth group - a sample of Catholic Seminarians - like the other groups is a small community with a structured life-style, but its life-style and value-system is not necessarily non-conformist. These groups are all to be found, amongst other places, in Johannesburg, apart from the Catholic Priests, all of whom were living in a seminary in Pretoria. All the members of these religious communities - both men and women - who were interviewed were Caucasian, their educational standard ranged from pre-matric through to university graduate status, and the overall average age of the 9rouP members was 24 years - the youngest subject was aged 17 while the oldest was 31 years of age. Rather than a meas~rement orientated procedure, a phenomenologically inspired methodological procedure was used to explicitate the data. It is argued that a descriptive phenomenological perspective is more appropriate for the elucidation of meaning-structures, especially with reference to the present inquiry, than would be a quantitative, measurement and mathematical treatment of the subject matter with which this thesis is concerned. The results are best summarized by stating that, although the explication revealed that the four groups are distinctly different in certain aspects of the meaning-structures of the individuals' becoming and being members of a group, there are nonetheless marked similarities between the groups in other aspects of the explicitated data.
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