5 topics with brief reviews: definitions, key facts, and class questions.
Chemical reactions are the foundation upon which the understanding of metabolism, pharmacodynamics, and physiological processes is built. In this chapter, we analyze the basic principles of the conversion of substances into one another, without which it is impossible to master either biochemistry or clinical disciplines.
The section covers key concepts: from the classification of chemical reactions to the features of processes involving gases. Special emphasis is placed on calculations. You will learn how to correctly operate with the concept of "amount of substance" and apply the stoichiometric rule—your main mathematical tool in chemistry.
In seminars and colloquia, instructors most often demand not just rote memorization of theory, but a practical skill: the ability to quickly determine the type of reaction, balance coefficients, and solve problems involving stoichiometry and gas laws. Study this material thoroughly—it will save you a lot of time in your upper years.
What is the difference between reactants and products?
Reactants are the starting substances that enter into interaction (on the left side of the equation). Products are the new substances formed as a result of the reaction (on the right side of the equation).
What is the main difference between molar mass and relative molecular mass?
They are completely numerically identical due to how the Avogadro constant is established. The only difference is that molar mass is a dimensional quantity (g/mol) showing the mass of one mole, whereas relative molecular mass is a dimensionless quantity.
What does the reduced amount of substance ($n'$) indicate?
This is a quantity equal to the actual amount of substance in moles divided by its stoichiometric coefficient in the equation. It shows how many theoretical "turns" of the reaction can be carried out with a given amount of reactant.
What is the main criterion for the classification of chemical reactions?
The main criterion is how exactly the quantitative composition and nature of the starting reactants change compared to the resulting reaction products.
Why is humid air lighter than dry air at constant pressure?
Equal volumes contain an equal number of particles. Water molecules have a mass of 18 g/mol, and when they replace heavier nitrogen and oxygen molecules (average mass 29 g/mol), the overall air density decreases.
Master the entire topic in the "Chemistry" course
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3,009 pages of study guides for all topics
Assignments and quizzes after every topic — just like in a colloquium