What is a stem cell? Ultimately, every cell in the human body can be traced back to a fertilized egg that came into existence from the union of egg and sperm. But the body is made up of over hundreds of different types of cells. All of these cell types come from a pool of […]
Posts in the 2nd Year category:
Chapter 5 : Kinetics – speed of reaction
Kinetics Kinetics is a field of the chemistry that studies the speed of reactions. The speed of a reaction can depend on the conditions of the reaction. For instance, when we put H2(g) and O2(g) we don’t produce water spontaneously. This reaction has a very negative ΔG0. However, if we produce a spark, the reaction […]
Chapter 4 : Kinetics – Equilibrium
Chemical kinetics is the study of the speed of reactions. The speed of reaction is determined by the variation of the quantity of species by unit of time. Usually, we consider the concentrations for species in solution and we consider pressures for gases. The speed of a reaction is rarely constant and is positive until […]
Chapter 3 : thermodynamics – second and third principles
Second principle Increase of the entropy: The entropy in the universe increases over time. The entropy is a measure of the disorder of a system. The second law of thermodynamics has several formulations but the most common is that a process is spontaneous if, without external influence (isolated system), it induces an increase of the […]
Chapter 2 : Methods of separation – extraction
Methods of separation One job of a chemist is to analyse samples of chemicals. To determine the composition of the sample, a separation of the different elements is necessary to avoid interferences between the species. It can be of importance to determine which chemical elements are present, in which quantities and oxidation state. Several methods […]
Chapter 1 : Thermodynamics – First principle
The thermodynamics is the study of the transfer of energy and especially of heat. It is important to make the distinction between heat (q) and temperature (T). The temperature reflects the motion of particles and is connected to their kinetic energy, but the temperature is no energy. Heat is an energy that exist if there […]
Chapter 4f: solids – conductivity
Electric conduction Some solids are conducting the electricity and some are not. We will explain here from where the conductivity comes and the difference between a conductor and an insulator. The conductivity is explained by the band theory. We have seen in the section on molecular orbitals that liaisons are the combination of the atomic orbitals […]
Chapter 1: sequences and series
Sequences and series Consider the following sum: The dots at the end indicate that the sum goes on forever. Does this make sense? Can we assign a numerical value to an infinite sum? While at first it may seem difficult or impossible, we have certainly done something similar when we talked about […]