Percentage Composition
Chapter Name : Some Basic Concepts Of Chemistry |
Sub Topic Code : 102_11_01_09_02 |
Topic Name : Percentage Composition |
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Sub Topic Name : Empirical Formula For Molecular Formula |
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Introduction
Empirical Formula – formula of a compound that expresses lowest whole number ratio of atoms. Molecular Formula – actual formula of a compound showing all the number of atoms present
Pre-Requisites:
Mass, atom, element, compound, molar mass, percent composition
Activity:
Water – H2O- and peroxide (H2O2)-both colorless liquids, having the same elements but have different properties due to the number of atoms of the two elements. (H and O)
Real Life Question:
What are water, salt and glucose, made of? How can you easily identify which compound u have given the chemical formula?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Empirical Formula | Formula of a compound that expresses lowest whole number ratio of atoms. |
| Molecular Formula | Actual formula of a compound showing all the number of atoms present. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Calculator | Calculating the molar masses, percent composition |
Real life uses :
Finding the molecular formula of an unknown compound.
Places to visit :
Kitchen.
Practical examples around us
| Examples | Explainations |
|---|---|
| Glucose and other sugars, lactose (lactogen) | They have the same elements just in different proportions. Thus making the properties different for each compound. |
What you learn in Theory:
Empirical Formula – formula of a compound that expresses lowest whole number ratio of atoms. Molecular Formula – actual formula of a compound showing all the number of atoms present.
What you learn in Practice:
It is not just the ratio of the atoms in a compound important but the numbers of atoms in an element tell the exact composition and makeup the identity of a compound.