S1.1 An Introduction to Matter
1.1.1: Composition of Matter
Chemistry is the study of matter, and matter is everywhere around us. On the same notion, energy is everything that exists but does not have the properties of matter. Matter & energy are intertwined, as energy is considered a property of matter (e.g., ability to perform work or produce heat).
Matter is also divided into two categories: Pure Substances & Mixtures. Pure Substances have a definite and uniform chemical composition where as mixtures have a combination of two or more pure substances that retain their individual properties. The diagram sums up the types of pure substances and mixtures.
Important for 1B : Separation Techniques
Filtration
Filtration is a method used to separate solids fromliquids or other mixtures by using filter paper and a funnel. The solid particles, known as the residue, remain on the filter paper, while the liquid, called the filtrate, passes through and is collected in a beaker.
Distillation
Distillation is a separation technique in which a mixture is heated until its components vaporize at different temperatures. It relies on the principle that different substances have different boiling points, allowing themto be separated as each component vaporizes and condenses at its specific temperature.
Paper Chromatography
In paper chromatography, a mixture is placed on a piece of paper and then submerged in a solvent. As the solvent travels up the paper, the components of the mixture move with it. The more soluble a component is, the faster and farther it travels along the paper.
Crystallization
In crystallization, the mixture is first dissolved in a hot solvent and then allowed to cool. As the solution cools, crystals begin to form and can then be separated by filtration.
Dissolution
In dissolution, also known as solvation, the soluble component of a mixture dissolves in a solvent such as water or an organic liquid. Meanwhile, any insoluble substances remain undissolved and can be separated from the solution.
1.1.2: States of Matter
The three main states of matter are: Solid, Liquid & Gas.
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- Solids have fixed volumes & shapes; strong forces; and are not compressible.
- Liquids have fixed volumes but no fixed shapes; moderate forces; & are not compressible
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- Gases don’t have fixed volumes/shapes; weak forces; but are compressible
1.1.3: The Kelvin scale
In IB chemistry, the Kelvin (K) is the SI unit for temperature. It is used globally in scientific measurements because it begins at absolute zero, the point at which all molecular motion stops.
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To convert between degrees Celsius (°C) and Kelvin (K), we use the following equation:
K = °C + 273.15
When a substance changes state, temperature remains constant during the phase change. The energy added during this process is not used to increase temperature, but rather to overcome intermolecular forces (Explored in more detail in structure 2.2). This energy is called the latent heat of vaporization, and it is the amount of heat required to turn a unit mass of a liquid into a gas without changing its temperature. This can be represented through the heating curve of water
