Lesson Notes By Weeks and Term - Senior Secondary 2

TERM׃ 1^ST TERM

WEEK SEVEN

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:        

Subject: Chemistry

Topic: MASS, VOLUME RELATIONSHIP 1

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. State the mass volume relationship.
2. Identify and explain some basic concepts relating to mass volume relationship.
3. Explain the condition for Standard Temperature and Pressure (STP).
4. Differentiate between relative volume and relative molar mass.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION	TEACHER’S ACTIVITY	STUDENT’S ACTIVITY
STEP 1 INTRODUCTION	The teacher explains mass volume relationship to the students.	Students pay attention
STEP 2 EXPLANATION	He discusses the basic concepts of mass volume relationship.	Students pay attention and participates
STEP 3 EXPLANATION	Teacher explains the  condition for Standard Temperature and Pressure (STP).	Students pay attention and participates
STEP 4 EXPLANATION	Teacher differentiates between relative volume and relative molar mass.	Students pay attention and participates
STEP 5 NOTE TAKING	The teacher writes a summarized note on the board	The students copy the note in their books

 

NOTE

MASS, VOLUME RELATIONSHIP 1

Relationship between quantities

M = m/n

Molar volume = mass/amount, M = N/A

Avogadro’s constant = L = N/A = Number/Amount.

A mole is the amount of a substance containing Avogadro’s number of formular units. The formula of a compound tells us the elements present in it. It lso tells us the amount of different elements present in it. These amounts are usually expressed as a mole ratio of the different elements.

For example, In Na₂SO₄

                                   Sodium         Sulphur           Oxygen

Number of moles            2                    1                      4

Mole ratio                       2         :         1          :           4

A balanced equation of a chemical reaction tells us the relationship of the amount of the reactants to one another and to the products. This relationship between the amount of reactants and products is known as the stoichiometry of the reaction.

The following table summarizes the differences between mass and volume:

Basic concepts

1. Mole:

   - The mole is a unit used in chemistry to express amounts of a substance.

   - One mole (1mol) of a substance contains Avogadro's number (6.022 x 10²³) of entities (atoms, molecules, ions, etc.).

2. Molar Quantity:

   - Molar quantity refers to a quantity expressed in moles.

   - For example, molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol).

   - Molar volume is the volume occupied by one mole of a substance and can vary based on the state of matter (e.g., gases have a molar volume at standard temperature and pressure).

3. Molarity:

   - Molarity (M) is a measure of the concentration of a solute in a solution.

   - It is defined as the number of moles of solute divided by the liters of solution (M =moles of solute/liters of solution).

   - Molarity is expressed in moles per liter (mol/L) or M).

Standard temperature and pressure

Standard Temperature and Pressure (STP) is a set of standard conditions used for comparing and measuring properties of gases. These conditions provide a reference point for gas-related calculations and are defined as follows:

1. Standard Temperature (ST):

   - The standard temperature for STP is ⁰C (degrees Celsius) or (273.15 K) (kelvins).

   - This temperature is chosen for its practicality and is commonly used in scientific and engineering contexts.

2. Standard Pressure (SP):

   - The standard pressure for STP is 1 atm (atmosphere) or (101.325 kPa) (kilo-pascals).

   - This pressure is equivalent to the average atmospheric pressure at sea level on Earth.

The combination of ⁰C and 1atm creates a standardized set of conditions that allows for consistent comparisons of gases. Under STP, one mole of an ideal gas occupies a volume of approximately 22.414 L. This relationship is derived from the Ideal Gas Law and is useful in various applications, such as stoichiometry and determining molar volumes.

NOTE: STP is particularly valuable when working with gases because it provides a benchmark for understanding how gases behave under specific, well-defined conditions.

Relative density and relative molar mass

Relative Density

Relative density, also known as specific gravity, is the ratio of the density of a substance to the density of a reference substance.

   - The reference substance is often water for liquids and solids, and air or hydrogen for gases.

   - Mathematically, relative density (RD) is expressed as: [ RD = Density of Substance / Density of Reference Substance]

   - Relative density is a dimensionless quantity, and it provides a measure of how dense a substance is compared to the reference substance.

Relative Molar Mass

Relative molar mass is the ratio of the average molar mass of one molecule or formula unit of a substance to the unified atomic mass unit (u or amu).

   - It is also known as the molecular weight or molar mass.

   - Mathematically, relative molar mass (M_r) is expressed as:  M_r = Average Molar Mass of Substance / Unified Atomic Mass Unit (1 amu)

   - The unit of relative molar mass is therefore dimensionless.

EVALUATION:

                           - Discuss the relationship between mass and volume.

                            - What is Standard Temperature and Pressure (STP)

                            - Differentiate between relative density and relative molar mass.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively