As he began to teach inorganic chemistry, Mendeleev could not find a textbook that met his needs. Since he had already published a textbook on organic chemistry in 1861 that had been awarded the prestigious Demidov Prize, he set out to write another one. The result was Osnovy khimii (1868–71; The Principles of Chemistry), which became a classic, running through many editions and many translations. When Mendeleev began to compose the chapter on the halogen elements (chlorine and its analogs) at the end of the first volume, he compared the properties of this group of elements to those of the group of alkali metals such as sodium. Within these two groups of dissimilar elements, he discovered similarities in the progression of atomic weights, and he wondered if other groups of elements exhibited similar properties. After studying the alkaline earths, Mendeleev established that the order of atomic weights could be used not only to arrange the elements within each group but also to arrange the groups themselves. Thus, in his effort to make sense of the extensive knowledge that already existed of the chemical and physical properties of the chemical elements and their compounds, Mendeleev discovered the periodic law.
A.) In the beginning the universe was too hot for atoms to exist.
Because choice b,c,and d are all part of the big bang theory.
Answer:
C) 0.800 mol
Explanation:
In order to <u>convert from moles of Al₂O₃ into moles of Al</u>, we'll need to use<em> the stoichiometric coefficients</em>, using a conversion factor that has Al₂O₃ moles in the denominator and Al moles in the numerator:
- 0.400 mol Al₂O₃ *
= 0.800 mol Al
So the correct answer is option C).
The law of conservation of energy is that energy cannot be created or destroyed, but it can be transferred or transformed from one form to another (including transformation into or from mass, as matter). The total amount of energy in a closed system never changes. energy in a system may be transformed so that it resides in a different state.
