p.2
Classification of Matter
How is matter classified?
Into mixtures and pure substances.
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
Is air a pure substance?
No, air is a mixture of gases.
p.5
Mixtures vs. Pure Substances
How are compounds formed?
Compounds are formed through chemical reactions between elements.
p.7
Physical and Chemical Properties
What is the melting point?
The temperature at which a substance melts (changes from solid to liquid).
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 one common use of oxygen in the atmosphere?
Cutting and welding metals.
p.2
Elements and Compounds
What are hydrogen and oxygen classified as?
Elements, because they cannot be broken down further by chemical methods.
p.11
Composition of the Atmosphere
Why is carbon dioxide important to life on Earth?
It plays a crucial role in photosynthesis and makes up about 0.03% – 0.04% of the 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.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.6
Physical and Chemical Properties
What does 'taste' refer to?
The flavour of a substance.
p.7
Physical and Chemical Properties
What does malleability refer to?
How easily a solid can be rolled into sheets.
p.7
Physical and Chemical Properties
What is electrical conductivity?
The ability of a substance to transfer an electric current.
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.9
Physical Changes vs. Chemical Changes
What is meant by 'change of state'?
A physical change in which no new substances are produced.
p.3
Elements and Compounds
How can sodium chloride be produced?
By burning a piece of sodium metal in chlorine.
What is an example of a chemical change involving magnesium?
The reaction between magnesium and oxygen to form magnesium oxide (MgO).
p.8
Physical and Chemical Properties
What is the experiment mentioned in the notes?
Burning magnesium ribbon in air.
p.5
Mixtures vs. Pure Substances
What is the main difference between mixtures and compounds?
Mixtures consist of two or more substances that are not chemically combined, while compounds are substances formed when two or more elements chemically bond.
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.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.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 is an element?
A pure substance that cannot be broken down into anything simpler by chemical methods.
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.12
Fractional Distillation of Liquid Air
Why do oxygen and argon need further separation during fractional distillation?
Because their boiling points are very close (-183°C and -186°C respectively).
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.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
What will be discussed in the topic 'Planet Earth'?
The kinds of substances that can be extracted and methods for obtaining chemicals from various sources.
p.5
Mixtures vs. Pure Substances
Can the components of a mixture be separated easily?
Yes, the components of a mixture can be separated by physical means.
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 does ductility refer to?
How easily a solid can be pulled into wires.
p.2
Mixtures vs. Pure Substances
What are examples of pure substances found in air?
Nitrogen, oxygen, and carbon dioxide.
p.8
Physical and Chemical Properties
What does thermal conductivity refer to?
The ability of a substance to transfer heat.
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.1
Sources of Chemicals on Earth
From where can we obtain different substances?
The atmosphere, the ocean, and the Earth's crust.
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.6
Physical and Chemical Properties
What are physical properties in chemistry?
Properties that can be determined without changing the substance into other substances.
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.5
Mixtures vs. Pure Substances
Are the properties of a mixture the same as its components?
Yes, the properties of a mixture are similar to those of its individual components.
p.4
Properties of Mixtures and Compounds
Do iron and sulphur retain their original properties in a mixture?
Yes, they retain their original properties.
p.6
Physical and Chemical Properties
What are some examples of physical properties?
Appearance, odour, taste, and hardness.
p.5
Mixtures vs. Pure Substances
Do compounds have properties different from their constituent elements?
Yes, compounds have properties that are different from those of the elements that make them up.
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.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.3
Elements and Compounds
Give examples of compounds.
Water, carbon dioxide, common salt, and sugar.
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.6
Physical and Chemical Properties
What does 'odour' refer to?
The smell of a substance.
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.6
Physical and Chemical Properties
What is the significance of a substance's appearance?
It describes what a substance looks like, including its physical state and colour.
p.7
Physical and Chemical Properties
What is the boiling point?
The temperature at which a substance boils (changes from liquid to gas).
p.2
Classification of Matter
What is matter?
Anything that occupies space and has mass.
How does bleach remove stains?
By causing a chemical change.
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.12
Fractional Distillation of Liquid Air
What is the boiling point of nitrogen, and where is it collected during fractional distillation?
Nitrogen has the lowest boiling point at -196°C and is collected at the top of the fractionating column.
What is a chemical change?
A change in which one or more new substances are produced.
p.2
Elements and Compounds
Why is water not considered an element?
Because it can be broken down into hydrogen and oxygen.
p.11
Chemical Tests for Gases
What is the observation when carbon dioxide is bubbled through limewater?
It turns from colorless to milky.
p.2
Physical and Chemical Properties
What is electrolysis?
The decomposition of water into hydrogen and oxygen by passing electricity through it.
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.2
Mixtures vs. Pure Substances
What defines an impure substance?
An impure substance is always a mixture.
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 are the boiling points of liquid oxygen and liquid argon?
Liquid oxygen boils at -183°C and liquid argon at -186°C.
What is an example of a chemical change involving acids?
Acid-alkali neutralization.
p.11
Chemical Tests for Gases
What is the role of anhydrous copper(II) sulfate in testing for water?
It turns from white to blue when water is present.
