Investigación sobre las concepciones de los estudiantes acerca de los estados de agregación y los cambios de estado

In this work the results of a test based on phase changes and the states of matter are discussed. They show heavy misconceptions in pupils, 15-16 years old, in the first two years of Italian Secondary Upper School. Pupils show best results when they must work with experimental situations but show difficulties to pass from verbal to graphical language

Il problema della comunicazione linguistica a scuola : il linguaggio scientifico e chimico in particolare

In this work first of al1 we notice the importance of linguistic communication at school and we underline the fact that every teacher, regardless of his discipline, has the problem of making himself understood. Then, for what concernes scientific language, we give some methodological directions. Finally we give prominence to chemical language and to the role that this language could have in teaching

Heats of formation of lanthanum-antimony alloys

Heats of formation in the LaSb system have been measured using a small furnace isoperibol calorimeter. The compositions and states of the alloys prepared in the calorimeter were checked by metallographic and X-ray analyses. The following values of \u394Hform (kcal (g atom)-1 \ub1 0.5) were obtained for the various compounds, for reaction in the solid state at 300 K: La2Sb, -23.4; La5Sb3, -25.5; La4Sb3, -28.4; LaSb, -31.2; LaSb2, -22.0. The experimental data are discussed briefly and found to be in good agreement with those computed according to Miedema's model and, for the La-rich alloys, also with those calculated according to Kubaschewski's suggestion based on the effective coordination number. \ua9 1979