Glossary

Acids Acids are the substance which gives H+ ions in water.
Arrhenius acids Arrhenius acids are substances that dissociates in water to give hydrogen ions H+ (aq).
Arrhenius bases Arrhenius bases are substances that produce hydroxyl ions OH– (aq).
Aqueous tension Pressure exerted by saturated water vapour is called aqueous tension.
Avogadro Constant The number of molecules in one mole of gas is determined as 6.022x1023 and is known as Avogadro constant.
Avogadro Law Avogadro’s law states that equal volumes of all gases under the same conditions temperature and pressure contain equal number molecules.
Brönsted-Lowry theory Acid is a substance that is capable of donating a hydrogen ion H+ and bases are substances capable of accepting a hydrogen ion, H+.
Boiling temperature The temperature at which vapour pressure of liquid is equal to the external pressure is called boiling temperature at that pressure.
Boyle’s Law (Pressure - Volume Relationship) At constant temperature, the pressure of a fixed amount (i.e., number of moles n) of gas varies inversely with its volume.
Boyle temperature The temperature at which a real gas obeys ideal gas law over an appreciable range of pressure is called Boyle temperature or Boyle point.
Buffer Solutions The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali.
Charles’ law The law states that pressure remaining constant, the volume of a fixed mass of a gas is directly proportional to its absolute temperature.
Coefficient of viscosity Viscosity coefficient is the force when velocity gradient is unity and the area of contact is unit area. ‘ η’ is measure of viscosity
Common ion effect It can be defined as a shift in equilibrium on adding a substance that provides more of an ionic species already present in the dissociation equilibrium.
Compressibility factor(z) The deviation from ideal behaviour can be measured in terms of compressibility factor Z, which is the ratio of product pV and nRT. Mathematically Z =pV/ nRT.
Critical pressure The minimum pressure required to liquify the gas at critical temperature.
Critical temperature The temperature above which liquid cannot be liquified by applying pressure.
Critical volume The volume of one mole of gas at critical temperature and pressure.
Dalton’s Law of Partial Pressures It states that the total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases
Electrolytes The substances that conduct electricity in their aqueous solutions are called electrolytes.
Equilibrium state The state at which measurable properties are found to be constant.
Equilibrium Law At a given temperature, the product of concentrations of the reaction products raised to the respective stoichiometric coefficient in the balanced chemical equation divided by the product of concentrations of the reactants raised to their individual stoichiometric coefficients has a constant value. This is known as the Equilibrium Law or Law of Chemical Equilibrium.
Equilibrium vapour pressure an equilibrium is established between liquid phase and vapour phase. Vapour pressure at this stage is known as equilibrium vapour pressure or saturated vapour pressure.
Gas Laws The laws which gives the relationship between measurable properties of gases.
Gay Lussac’s law It states that at constant volume, pressure of a fixed amount of a gas varies directly with the temperature.
Henry’s law The law states that the mass of a gas dissolved in a given mass of a solvent at any temperature is proportional to the pressure of the gas above the solvent.
Homogeneous Equilibrium In homogeneous equilibrium all the reactants and products are in the same phase.
Heterogeneous Equilibria Equilibrium system having more than one phase is called heterogeneous equilibrium
Henderson–Hasselbalch equation provides a relationship between the pH of acids (in aqueous solutions) and their pKa (acid dissociation constant)
Ideal gas A gas that follows Boyle’s law, Charles’ law and Avogadro law strictly is called an Ideal gas.
Ideal gas equation The Boyle’s law, Charles’ law and Avogadro law combined together in a single equation which is known as ideal gas equation. pV = n RT
Ionic equilibrium The equilibrium involving ions in aqueous solution is called ionic equilibrium.
Intermolecular forces The forces of attraction and repulsion between interacting particles atoms and molecules.
Isobar Each line of the volume vs temperature graph at constant pressure.
Isochore Each line of the volume vs temperature graph at constant volume.
Isotherm The curve corresponds to constant temperature is known as an isotherm (constant temperature plot)
Laminar flow The type of flow in which there is a regular gradation of velocity in passing from one layer to the next is called laminar flow.
Le Chatelier’s Principle It states that a change in any of the factors that determine the equilibrium conditions of a system will cause the system to change in such a manner so as to reduce or to counteract the effect of the change.
Lewis concept of Acid and Base An acid is a species which accepts electron pair and base which donates an electron pair.
Most probable speed Speed possessed by maximum number of molecules. The speed that corresponds to the peak of the Maxwell distribution is called the most probable speed.
Normal boiling point At 1 atm pressure boiling temperature is called normal boiling point.
Partial pressure In a mixture of gases, the pressure exerted by the individual gas is called partial pressure.
pH scale The pH of a solution is defined as the negative logarithm to base 10 of the activity (aH)+ of hydrogen ion.
Root mean square speed The square root of the mean of the square of speeds then we get a value of speed which is different from most probable speed and average speed. This speed is called root mean square speed.
Standard temperature and pressure Standard temperature and pressure means 273.15 K (0°C) temperature and 1 bar (i.e., exactly 105 pascal) pressure.
Standard boiling point If pressure is 1 bar then the boiling point is called standard boiling point of the liquid.
Surface tension Surface tension is defined as the force acting per unit length perpendicular to the line drawn on the surface of liquid.
Solubility product The solubility product, Ksp, of an ionic compound is defined as the product of the concentration of the ions that exist in equilibrium with the solid compound in a saturated solution.
Viscosity It is the measure of resistance to flow which arises due to the internal friction between layers of fluid as they slip past one another while liquid flows