Chemical Composition & Recycling

Exploring Diversity of Matter by Its Chemical Composition

• It is important to understand the utilization of recycling bins correctly and how to make use of them
• Correct materials must be disposed of correctly in the recycling bins, E-waste must be disposed of properly to avoid damage to the environment

Understanding Chemical Composition and its Real-World Applications

• Understanding the chemical composition of everyday items, including food and waste materials, is important and affects our daily lives
• Melamine is a substance used to make objects that are strong, light, and easily molded, but it can be harmful if used in food products because it contains nitrogen
• In 2008, unethical manufacturers added melamine to milk powder to trick health inspectors into thinking that poor-quality milk powder had a high protein content because they have similar chemical compositions

Lina's Story

• Lina consumed melamine-tainted milk powder, altering the course of her life
• Sanlu Group produced 300,000 milk formula powder that contaminated the banned chemical Fonterra
• As teenagers, they still experience melamine poisoning
• Lina, now 14, has learning difficulties and struggles with basic math skills

Exploring the Three Types of Matter

• The basic types of matter are elements, compounds, and mixtures
• Elements, compounds, and mixtures can be distinguished from each other based on their properties.

Elements: The Foundation of Matter

• Elements are the basic building blocks of matter, that includes living and non-living things
• Elements cannot be broken down into simpler substances.
• There are 118 known elements, which are represented by chemical symbols in the Periodic Table of Elements
• The Periodic Table of Elements arranges elements based on their properties
• Elements in the same group have similar chemical properties.
• Element properties change from metals to metalloids to nonmetals across a period
• Chemical Symbols: Used to represent different elements
• Each element has a unique symbol and an atomic number

Technetium

• Technetium, represented by the symbol Tc, is element number 43
• Technetium the first element to be artificially created in a laboratory in 1937
• Technetium cannot exist naturally due to its unstable nature and because element 42 could be obtained from an unwanted laboratory apparatus

Compounds: Combining Elements

• Compounds consist of two or more elements that are chemically combined together
• Water is formed through a chemical reaction when hydrogen and oxygen combine
• Carbon dioxide is a greenhouse gas necessary for photosynthesis but contributes to climate change when accumulated
• Sodium chloride (common salt) is made of sodium and chlorine and used as a food preservative
• Sodium hydrogencarbonate (baking soda) contains sodium, hydrogen, carbon, and oxygen and is used in baking and as an antacid
• Ammonia cleaning products are created with nitrogen and hydrogen

Additional Examples of Compounds

• Marble contains calcium, carbon, and oxygen
• Glass contains silicon, calcium, carbon, and oxygen.
• Plastic contains carbon, hydrogen, and oxygen

Properties of Compounds

• Compounds do not have the same properties as their constituent elements
• Hydrogen and oxygen are gases at room temperature, but when chemically combined, they form water, which is a liquid
• Carbon is a solid and oxygen is a gas at room temperature. They chemically combine to form carbon dioxide, which is a gas.
• The elements in a compound are always chemically combined in a fixed proportion by mass
• Carbon dioxide always has 1 carbon and 2 oxygen atoms
• Methane always has 1 carbon and 4 hydrogen atoms
• Ammonia always has 1 nitrogen and 3 hydrogen atoms
• It is challenging to separate compounds into constituent elements
• Large amounts of energy is required

Mixtures: Combining Elements and Compounds Physically

• Mixtures are made up of two or more elements and/or compounds that are not chemically combined
• Air is a mixture that contains nitrogen, oxygen, carbon dioxide, and water vapour.
• Air composition in different locations varies

Air Quality and Pollutants

• Air quality is measured using the Pollutant Standards Index (PSI)
• Normal outdoor activities are safe with PSI values under 100
• For people with heart or lung diseases, PSI values over 100 should avoid exercise

Types of Mixtures

• Made from elements only
• Steel is an iron mixture with other elements
• Pewter is a tin mixture with copper and silver
• Made from compounds only
• Concrete contains calcium carbonate, silicon dioxide, and water
• Salt solution and coffee contain multiple compounds
• Made from elements and compounds
• Fuel is a mixture of carbon-containing compounds and can contain sulfur
• Milk has compounds such as iron, phosphorus, and calcium
• Seawater includes sodium chloride and magnesium chloride
• Mixtures retain the properties of their constituents
• Water with common salt, results in a salty taste
• Mixtures that do not have fixed proportions can be separated easily
• Can form solutions by mixing amounts of common salt with water and then recovery of the salt using a separation technique

Solutions

• A solution the where one substance dissolves completely in another
• A solution is made of solute: Substance that dissolves, which is called the solute
• A solution is also made of solvent: Substance in which the solute dissolves
• Examples include mineral water and soda water
• Solute particles become unseen in a solution
• Torch light will fully pass through the solution

Concentrated and Diluted Solutions

• Diluted Solution: Low percentage of dissolved solute
• Concentrated Solution: High percentage of dissolved solute

Solutions and Rate of Dissolving

• Soluble: When a solute dissolves completely in a solvent
• Insoluble: Substances that do not dissolve in a given solvent
• Rate of Dissolving: rate a solute dissolves in a solvent
• Solute particles size
• Temperature of solvent
• Rate of stirring

Suspensions

• Suspension: When insoluble substances are in a solvent
• Dirty water is a suspension because it has insoluble substances in water

Properties of Suspensions

• Other examples of suspensions include wastewater, calamine lotion and certain soups
• Insoluble substances settle to the bottom in solid deposits when left undisturbed
• Torch light will not pass through it
• Can be removed through a process called filtration

Differences Between Solutions and Suspensions

• Suspension: Insoluble substances can be seen, Substances settle to form solid deposits and light cannot pass through fully
• Solution: Particles of the solute cannot be seen, Substances don't settle to form solid deposits and light will fully pass through fully

Distinguishing Matter: Elements, Compounds, and Mixtures

• Elements are one element
• Compounds are two or more elements
• Mixtures are two or more elements or compounds