Greater Minds Tutors

The Kinetic Theory of Matter postulates that matter is made up of tiny particles that are continuously in motion and so possess kinetic energy . It is also known as the Molecular Theory. The particles may be atoms, molecules or ions. Recall that matter exists in three common states, namely solid, liquid and gaseous states; although, we also have plasma and Einstein-Bosé condensate as additional states of matter. However, these are beyond our scope of discussion. The major differences in the properties of solid, liquid and gas are the degrees of intermolecular forces of attraction and average kinetic energy of the particles. While the intermolecular force is strongest in the solid state, which confers upon a solid its rigidity in shape and form, it is weakest in the gaseous state, which explains why a gas is formless and takes the shape and volume of the containing vessel. The intermolecular force of attraction is however, mild (not very strong and not very weak) in the liquid sta...

Gas Laws These are empirical laws that are used to explain the behaviour of ideal gases. An ideal gas is a perfect gas. It is a gas that does not exist, because there is no perfect situation in the real world. The Gas laws are grouped into two major categories - the physical and chemical laws. The former seek to explain the behaviour of gases based on their physical properties such as volume, temperature and pressure, while the latter do so by using their chemical properties like the number of molecules in the gases. We had looked at the chemical laws in our post - Gas Laws (Part II): Gay Lussac's & Avogadro's Laws , so this post will be devoted to the discussion on the physical laws. Boyle's Law This law states that the volume, V, of a given mass of gas is inversely proportional to its pressure, P, provided the temperature remains constant. This implies that if the volume of a gas is doubled, it will lead to a decrease in the gas pressure by half. Simil...

pH Chart In our last post: Types, Preparation & Uses of Salts , we studied that salts are the products of the neutralization reactions between acids and bases. Following this fact, all salts are expected to have a neutral pH of 7 in solution. Interestingly, some salts produce solutions with pH > 7 (basic solutions), while others produce acidic solutions with pH < 7. Such salts, which are the products of either weak acids and strong bases or strong acids and weak bases, decompose in water to form two products. This phenomenon is known as hydrolysis. Recall that from our post on pH in Acids & Bases (Part III) , we learnt that water contains equal concentration of hydrogen and hydroxide ions. Therefore, the dissolution of a salt in water is likely to upset this ionic equilibrium based on the salt's composition. This is the underlying principle of hydrolysis of salts. So, in this post, we shall be looking at the hydrolysis of different types of salts based on th...

Introduction Before they are introduced to acids and bases, young chemistry students always think that sodium chloride (common salt) is everything there is to know about salts. However, from their knowledge of acids and bases, they also get to know about other substances, such as copper (II) tetraoxosulphate (VI), potassium trioxocarbonate (IV), ammonium chloride, calcium trioxonitrate (V) etc, which are classified as salts. These substances are the outcomes of the Arrhenius acid-base reactions. So, what is a salt? Definitions We will define a salt in terms of basicity (replaceable hydrogen ions) and neutralization. I) A salt is a substance formed when all or part of the replaceable hydrogen ions in an acid, are replaced by metallic ions (Na+, K+, Mg2+, Ca2+, Cu2+ etc) or ammonium ions (NH4+). This implies that every acid has its corresponding salts. The list below shows examples of some salts and their parent acids. 1. Acid : Hydrochloric acid (HCl) Salts : Sodium chloride...

p H & pH Scale The pH (hydrogen ions potential) is a measure of the acidity or alkalinity of a solution. The concept of pH was introduced by Sörensén in 1909 to bring about the convenience of working with very dilute solutions. To this effect, he developed a scale consisting of fifteen numbers (0 - 14), which is used in pH meter, for measuring the relative acidity or alkalinity in solutions. This scale is known as the pH scale. The numbers in the pH scale are the values of the negative logarithms of the hydrogen ions concentrations in such solutions. From the above, we can define pH as the negative logarithm of the hydrogen ions concentration [H+] to base 10. Mathematically, this is given as: pH = - log [H+] ..........................(i) Alternatively, the above equation can be expressed as pH = log 1/[H+] .........................(ii) From equation (ii), we can also define pH as the logarithm of the reciprocal of the hydrogen ions concentration to base 10. The...