Simple Mole Concept Notes

• A mole is defined as the amount of substance which contains equal number of particles (atoms / molecules / ions) as there are atoms in exactly 12.000g of carbon-12.

• One mole of carbon-12 atom has a mass of exactly 12.000 grams and contains 6.02 x 10²³ atoms.

The value 6.02 x 10²³ is known as Avogadro Constant.   

 N_A = 6.02 x 10²³ mol^-1

Example:

Calculate the number H atom in 1 mole of NH3.

Simple Mole Concept of Gases Notes

• Molar volume of any gas at STP = 22.4 dm³ mol^-1

• 1 mole of gas has a volume of 22.4 dm³ at s.t.p.
• At s.t.p, volume of gas (dm³) = number of mole X 22.4 dm³ mol^-1
• 1 mole of gas has a volume of 24.0 dm³ at room temperature.
• At room temperature, volume of gas (dm³) = number of mole X 24.0 dm³ mol^-1

Calculate the number of bromide ions in 2 moles of CaBr2

Acids and Bases Quiz

• Define acid and base according to the Arrhenius concept. Give an example for your answer.
• Define the term conjugate acid-base pair.
• Define amphiprotic species.
• Define an acid and a base according to the Brønsted–Lowry concept. Give an acid–base equation and identify each species as an acid or a base.
• What is meant by the conjugate acid of a base?
• Write an equation in which H₂PO₃ acts as an acid and another in which it acts as a base.
• Define an acid and a base according to the Lewis concept. Give a chemical equation to illustrate.
• Explain why an acid–base reaction favors the weaker acid.
• Give two important factors that determine the strength of an acid. How does an increase in each factor affect the acid strength?
• Define autoionization. Write the expression for Kw. What is its value at 25˚C?
• What is meant by the pH of a solution? Describe two ways of measuring pH.
• Which is more acidic, a solution having a pH of 4 or one having a pH of 5?
• Identify the relationship between the strength of an acid and that of its conjugate base.
• Identify the rules for determining the relative strengths of oxoacids.
• Identify the relative acid strengths of a polyprotic acid and its anions.

Explain the difference between orbit and orbital.

• Orbital refers to the volume in space around the nucleus where the probability of finding a particular electron in ˃ 95%.
• Orbit refers to the fixed circular path around the nucleus where a particular electron revolves.

Explain the difference between relative isotopic mass and relative atomic mass of a particular element.

• Relative isotopic mass is the mass of one atom of a particular isotope of the element. 
• Relative atomic mass is the average mass of all the isotopes present in a sample of naturally occurring element.