p.1
Sources of Chemicals on Earth
What are some examples of substances we need from Earth?
Clothes, food, medicines, etc.
p.1
Sources of Chemicals on Earth
From where can we obtain different substances?
The atmosphere, the ocean, and the Earth's crust.
p.1
Sources of Chemicals on Earth
What will be learned in the topic 'Planet Earth'?
The kinds of substances that humans can extract and methods for obtaining chemicals from various sources.
p.2
Classification of Matter
What is matter?
Anything that occupies space and has mass.
p.2
Classification of Matter
How is matter classified?
Into mixtures and pure substances.
p.2
Mixtures vs. Pure Substances
Is air a pure substance?
No, air is a mixture of gases.
p.2
Mixtures vs. Pure Substances
What are examples of pure substances found in air?
Nitrogen, oxygen, and carbon dioxide.
p.2
Mixtures vs. Pure Substances
What defines an impure substance?
An impure substance is always a mixture.
p.2
Elements and Compounds
What is an element?
A pure substance that cannot be broken down into anything simpler by chemical methods.
p.1
Sources of Chemicals on Earth
What is planet Earth considered as a source of?
A major source of chemicals needed for living standards.
p.8
Physical and Chemical Properties
What is the experiment mentioned in the notes?
Burning magnesium ribbon in air.
p.4
Mixtures vs. Pure Substances
What happens when black iron filings and yellow sulphur powder are mixed?
They form a yellowish grey mixture without any heat change.
p.6
Physical and Chemical Properties
What does the term 'property' refer to in chemistry?
Various characteristics of a substance.
p.7
Physical and Chemical Properties
What is solubility?
It refers to how well a substance (the solute) dissolves in another substance (the solvent).
p.6
Physical and Chemical Properties
What are some examples of physical properties?
Appearance, odour, taste, and hardness.
p.5
Mixtures vs. Pure Substances
What is a characteristic of compounds?
Compounds have a fixed composition and specific chemical properties.
p.9
Physical Changes vs. Chemical Changes
What is meant by 'change of state'?
A physical change in which no new substances are produced.
p.9
Physical Changes vs. Chemical Changes
What happens to the properties of a substance during a physical change?
Some properties, such as appearance, may change.
p.7
Physical and Chemical Properties
What is the melting point?
The temperature at which a substance melts (changes from solid to liquid).
p.7
Physical and Chemical Properties
What is electrical conductivity?
The ability of a substance to transfer an electric current.
p.11
Chemical Tests for Gases
What is the observation for carbon dioxide in a limewater test?
Carbon dioxide turns limewater from colorless to milky.
p.11
Composition of the Atmosphere
Why is carbon dioxide important to life on Earth?
Even though it makes up about 0.03% – 0.04% of the air, it is essential for life.
p.9
Physical Changes vs. Chemical Changes
What is a physical change?
A change in which no new substances are produced and the composition of a substance does not change.
p.4
Chemical Changes vs. Physical Changes
What occurs when the mixture of iron and sulphur is heated strongly?
They react to form a new substance called iron(II) sulphide, releasing a lot of heat.
p.8
Physical and Chemical Properties
What does thermal conductivity refer to?
The ability of a substance to transfer heat.
p.4
Properties of Mixtures and Compounds
What happens when a magnet is placed near the mixture of iron and sulphur?
The black iron filings are attracted by the magnet, while the yellow sulphur is not.
p.8
Physical and Chemical Properties
What are chemical properties of a substance?
Properties that describe the ability of that substance to react with other substance(s).
p.8
Physical and Chemical Properties
What is the observation expected from burning magnesium ribbon in air?
The magnesium ribbon burns brightly, producing a white light and forming magnesium oxide.
p.4
Mixtures vs. Pure Substances
Do iron and sulphur retain their original properties in the mixture?
Yes, they retain their original properties.
p.3
Elements and Compounds
Give examples of compounds.
Water, carbon dioxide, common salt, and sugar.
p.12
Fractional Distillation of Liquid Air
What method is used to separate the components of air?
Fractional distillation based on the difference in boiling points.
p.6
Physical and Chemical Properties
What does 'odour' refer to?
The smell of a substance.
p.12
Fractional Distillation of Liquid Air
What happens during the liquefaction stage of air separation?
The purified air is cooled and compressed, then allowed to expand, cooling further until it reaches -200°C to obtain liquid air.
p.3
Elements and Compounds
What is the definition of a compound?
A compound is a pure substance made up of two or more elements chemically combined together.
p.7
Physical and Chemical Properties
How is the solubility of a substance in water defined?
As the mass (in grams) of the substance that dissolves in 100 cm³ of water at a particular temperature.
p.10
Physical and Chemical Properties
What is a chemical change?
A change in which one or more new substances are produced.
p.7
Physical and Chemical Properties
What does ductility refer to?
How easily a solid can be pulled into wires.
p.3
Properties of Mixtures and Compounds
How do the properties of compounds compare to their constituent elements?
Compounds can have very different properties from their constituent elements.
p.5
Mixtures vs. Pure Substances
What is the main difference between mixtures and compounds?
Mixtures consist of two or more substances that are physically combined, while compounds are substances formed when two or more elements chemically bond.
p.6
Physical and Chemical Properties
What are physical properties in chemistry?
Properties that can be determined without changing the substance into other substances.
p.10
Physical and Chemical Properties
What is an example of a chemical change involving magnesium?
The reaction between magnesium and oxygen to form magnesium oxide (MgO).
p.11
Chemical Tests for Gases
What happens to a glowing splint in the presence of oxygen?
Oxygen relights a glowing splint.
p.5
Mixtures vs. Pure Substances
How can mixtures be separated?
Mixtures can be separated by physical methods such as filtration, distillation, or chromatography.
p.5
Mixtures vs. Pure Substances
Can the properties of a mixture be similar to its components?
Yes, the properties of a mixture can be similar to those of its individual components.
p.7
Physical and Chemical Properties
How is density defined?
As the mass (in grams) of the substance per unit volume (in cm³).
p.2
Elements and Compounds
What are hydrogen and oxygen classified as?
Elements, because they cannot be broken down further by chemical methods.
p.4
Properties of Mixtures and Compounds
How do the properties of iron(II) sulphide compare to those of iron and sulphur?
Iron(II) sulphide has many properties that are different from those of iron and sulphur.
p.7
Physical and Chemical Properties
What is the boiling point?
The temperature at which a substance boils (changes from liquid to gas).
p.11
Common Uses of Atmospheric Gases
What is a common use of carbon dioxide?
Making dry ice that acts as a refrigerant.
p.10
Physical and Chemical Properties
What is an example of a chemical change involving acids?
Acid-alkali neutralization.
p.5
Mixtures vs. Pure Substances
What happens to the properties of substances in a compound?
The properties of the individual elements change when they form a compound.
p.11
Common Uses of Atmospheric Gases
What is the common use of oxygen in the atmosphere?
Cutting and welding metals; making medical respirators to help patients with breathing difficulty.
p.12
Fractional Distillation of Liquid Air
What is the boiling point of nitrogen, and why is it significant in fractional distillation?
Nitrogen has the lowest boiling point at -196°C and boils off first during fractional distillation.
p.12
Fractional Distillation of Liquid Air
How are liquid oxygen and liquid argon separated in fractional distillation?
They are collected at the bottom of the fractionating column and further separated due to their close boiling points (-183°C for oxygen and -186°C for argon).
p.11
Composition of the Atmosphere
What is the approximate composition of air?
78% nitrogen, 21% oxygen, 0.9% argon, and 0.1% other gases.
p.6
Physical and Chemical Properties
What does 'hardness' refer to in the context of physical properties?
The ability of a substance to resist scratching.
p.3
Elements and Compounds
What is the chemical equation for the formation of sodium chloride?
2Na(s) + Cl2(g) → 2NaCl(s)
p.2
Mixtures vs. Pure Substances
Define a mixture.
A combination of two or more substances that retain their individual properties.
p.12
Fractional Distillation of Liquid Air
What is the first stage in the fractional distillation of liquid air?
Purification, where air is filtered and cooled to -80°C to remove carbon dioxide and water vapor.
p.7
Physical and Chemical Properties
What does malleability refer to?
How easily a solid can be rolled into sheets.
p.6
Physical and Chemical Properties
What are the two classifications of properties in chemistry?
Physical properties and chemical properties.
p.2
Physical and Chemical Properties
What is electrolysis?
The decomposition of water into hydrogen and oxygen by passing electricity through it.
p.9
Physical Changes vs. Chemical Changes
What happens when the vapor from sublimation is cooled?
It changes directly to solid.
p.11
Common Uses of Atmospheric Gases
What is nitrogen commonly used for?
Food packaging and as a refrigerant for storing living cells and tissues.
p.2
Elements and Compounds
Why is water not considered an element?
Because it can be broken down into hydrogen and oxygen.
p.6
Physical and Chemical Properties
What does 'taste' refer to in terms of physical properties?
The flavour of a substance.
p.3
Elements and Compounds
How can sodium chloride be produced?
By burning a piece of sodium metal in chlorine.
p.11
Chemical Tests for Gases
What happens to dry cobalt(II) chloride paper when it comes in contact with water?
It turns from blue to pink.
p.10
Physical and Chemical Properties
What is a common chemical change used for cleaning?
Removing stains on clothes with bleach.
p.11
Chemical Tests for Gases
What color change occurs when water is added to anhydrous copper(II) sulfate?
It turns from white to blue.
