Chem Notes
Boiling:
Process of converting a liquid into gas by heating it to its boiling point.
Used to separate a dissolved solid from a liquid.
The liquid boils away, leaving behind the solid residue.
Examples include separating salt from water in saltwater.
Simple Distillation:
Used to separate a mixture of two or more liquids with different boiling points.
The mixture is heated, and the liquid with the lower boiling point evaporates first.
The vapour is then condensed back into liquid form.
Examples include separating water from ethanol in alcoholic beverages.
Centrifugation:
Involves spinning a mixture at high speeds in a centrifuge.
Separates components based on their density.
Heavier components move towards the bottom while lighter components remain at the top.
Used in laboratories to separate solid particles from liquid solutions, such as blood cells from plasma.
Sedimentation:
Process of allowing solid particles to settle at the bottom of a liquid.
Takes advantage of the differences in density between the solid and liquid phases.
Used in wastewater treatment plants to separate suspended solids from water.
Filtration:
Separates solid particles from a liquid or gas by passing it through a porous barrier.
The solid particles are retained by the filter, while the liquid or gas passes through.
Examples include using filter paper to separate coffee grounds from brewed coffee.
Fractional Distillation:
Similar to simple distillation but used for separating a mixture of liquids with closer boiling points.
Involves multiple distillation steps to separate different fractions of the mixture.
Widely used in the petroleum industry to separate crude oil into various components like gasoline, diesel, and kerosene.
Chromatography:
Separation technique based on the differential movement of components through a medium.
Components with different affinities to the medium move at different rates.
Used extensively in chemistry labs to separate and analyse mixtures of chemicals, such as separating pigments in ink.
Separator Funnel:
Used to separate immiscible liquids (liquids that don't mix) based on their density.
The less dense liquid forms a layer on top and can be drained from the bottom of the funnel.
Often used in organic chemistry labs to separate organic solvents from aqueous solutions.
Structure of an Atom:
Electrons orbit the nucleus in energy levels or shells.
The nucleus contains protons (positive charge) and neutrons (no charge).
Trends in the Periodic Table:
Atomic Size: Decreases across periods (left to right), increases down groups.
Ionisation Energy: Increases across periods (left to right), decreases down groups.
Electronegativity: Increases across periods (left to right), decreases down groups.
Reactivity: Metals lose electrons, non-metals gain electrons.
Reactivity Series of Metals:
A list of metals in order of reactivity.
Highly reactive metals react vigorously, while less reactive metals react less vigorously.
Helps predict the behaviour of metals in chemical reactions.
Types of Bonds:
Ionic Bonds: Formed by the transfer of electrons, resulting in oppositely charged ions.
Covalent Bonds: Atoms share electrons to achieve stability.
Metallic Bonds: Formed by the sharing of outer electrons in metals, creating a "sea" of delocalised electrons.
Can give rise to cold-welding—a phenomenon where two clean metallic surfaces bond together in a vacuum or a space environment due to the sharing of free electrons, forming a metallic bond.
Acids are substances that release H⁺ ions (protons) when dissolved in water.
Hydrogen ions have a single positive charge.
The term "acid" comes from the Latin word "acidus," meaning sour.
Acid solutions contain negative ions (anions), which give the acid its name and determine the salt produced after neutralisation.
Examples of acids: HCl(Hydrochloric Acid), CH₃COOH(Acetic Acid), H₂SO₄(Sulphuric Acid), HNO₃(Nitric Acid).
Strong vs. Weak Acids:
Strong acids completely ionise in aqueous solutions.
E.g., HCl ionises into H⁺ and Cl⁻ ions, fully dissociating its components.
Examples of strong acids: hydrochloric acid, sulphuric acid, nitric acid etc.
Weak acids do not fully ionise in aqueous solutions.
E.g., Acetic Acid ionises partially as follows: CH₃COOH(aq) ⇌ H⁺(aq) + CH₃COO⁻ (aq).
Examples of weak acids: acetic acid, citric acid, carbonic acid.
Classification of Acids:
Based on the number of H⁺ ions they release when dissolved in water:
Monoprotic acids release 1 proton.
Diprotic acids release 2 protons.
Polyprotic acids release 3+ protons.
Concentration of Acids:
Concentrated vs. Dilute:
Concentrated solutions have more of the substance per unit volume.
Dilute solutions have less of the substance per unit volume.
The substance is always added to water, not the other way around.
Indicators:
Blue Litmus paper:
Turns red in the presence of an acid.
Remains blue for neutral and basic solutions.
Universal indicator paper:
Acids turn red.
Neutrals turn green.
Bases turn violet.
The strip can be placed directly onto a wet substance or a few drops of the solution can be dropped onto the universal indicator using dropping equipment.
Bases are substances that release OH⁻ ions.
Bases are also known as alkalis when soluble in water.
Examples include NaOH(Sodium Hydroxide), KOH(Potassium Hydroxide), Ca(OH)₂(Calcium Hydroxide).
All alkali solutions have pH values greater than 7.
Bases react with acids to produce salts and water only in a neutralisation reaction.
Most metal oxides and ALL hydroxides are considered bases.
Metal oxides (e.g., magnesium oxide) are basic in nature.
Non-metal oxides (e.g., carbon dioxide) are acidic in nature.
Properties of Bases:
React with acids to produce salts and other products.
Turn red litmus paper blue, phenolphthalein pink, and keep bromothymol blue blue.
Have a pH greater than seven at standard conditions.
Salts are ionic compounds formed by the reaction of an acid with a base.
They contain positively charged metal ions and negatively charged non-metal ions.
Common salts include nitrates, sulphates, and chlorides.
Salts are categorised based on the negative ion they contain.
All salts can conduct electricity and have various uses.
Examples include ammonium chloride in flashlight batteries, ammonium sulphate in fertilisers, calcium carbonate in the extraction of iron, and potassium nitrate in gunpowder.
Acid rain is any form of precipitation with acidic components.
It results from emissions of sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere, which react with water, oxygen, and other chemicals to form sulphuric and nitric acids.
Sources of SO₂ and NOₓ include burning fossil fuels, vehicle emissions, manufacturing, and industrial processes.
Effects of acid rain include:
Harm to acid-sensitive wildlife.
Restriction of tree growth.
Episodic acidification.
Corrosion of buildings and infrastructure.
Health issues from inhaling sulphate and nitrate particles.
Boiling:
Process of converting a liquid into gas by heating it to its boiling point.
Used to separate a dissolved solid from a liquid.
The liquid boils away, leaving behind the solid residue.
Examples include separating salt from water in saltwater.
Simple Distillation:
Used to separate a mixture of two or more liquids with different boiling points.
The mixture is heated, and the liquid with the lower boiling point evaporates first.
The vapour is then condensed back into liquid form.
Examples include separating water from ethanol in alcoholic beverages.
Centrifugation:
Involves spinning a mixture at high speeds in a centrifuge.
Separates components based on their density.
Heavier components move towards the bottom while lighter components remain at the top.
Used in laboratories to separate solid particles from liquid solutions, such as blood cells from plasma.
Sedimentation:
Process of allowing solid particles to settle at the bottom of a liquid.
Takes advantage of the differences in density between the solid and liquid phases.
Used in wastewater treatment plants to separate suspended solids from water.
Filtration:
Separates solid particles from a liquid or gas by passing it through a porous barrier.
The solid particles are retained by the filter, while the liquid or gas passes through.
Examples include using filter paper to separate coffee grounds from brewed coffee.
Fractional Distillation:
Similar to simple distillation but used for separating a mixture of liquids with closer boiling points.
Involves multiple distillation steps to separate different fractions of the mixture.
Widely used in the petroleum industry to separate crude oil into various components like gasoline, diesel, and kerosene.
Chromatography:
Separation technique based on the differential movement of components through a medium.
Components with different affinities to the medium move at different rates.
Used extensively in chemistry labs to separate and analyse mixtures of chemicals, such as separating pigments in ink.
Separator Funnel:
Used to separate immiscible liquids (liquids that don't mix) based on their density.
The less dense liquid forms a layer on top and can be drained from the bottom of the funnel.
Often used in organic chemistry labs to separate organic solvents from aqueous solutions.
Structure of an Atom:
Electrons orbit the nucleus in energy levels or shells.
The nucleus contains protons (positive charge) and neutrons (no charge).
Trends in the Periodic Table:
Atomic Size: Decreases across periods (left to right), increases down groups.
Ionisation Energy: Increases across periods (left to right), decreases down groups.
Electronegativity: Increases across periods (left to right), decreases down groups.
Reactivity: Metals lose electrons, non-metals gain electrons.
Reactivity Series of Metals:
A list of metals in order of reactivity.
Highly reactive metals react vigorously, while less reactive metals react less vigorously.
Helps predict the behaviour of metals in chemical reactions.
Types of Bonds:
Ionic Bonds: Formed by the transfer of electrons, resulting in oppositely charged ions.
Covalent Bonds: Atoms share electrons to achieve stability.
Metallic Bonds: Formed by the sharing of outer electrons in metals, creating a "sea" of delocalised electrons.
Can give rise to cold-welding—a phenomenon where two clean metallic surfaces bond together in a vacuum or a space environment due to the sharing of free electrons, forming a metallic bond.
Acids are substances that release H⁺ ions (protons) when dissolved in water.
Hydrogen ions have a single positive charge.
The term "acid" comes from the Latin word "acidus," meaning sour.
Acid solutions contain negative ions (anions), which give the acid its name and determine the salt produced after neutralisation.
Examples of acids: HCl(Hydrochloric Acid), CH₃COOH(Acetic Acid), H₂SO₄(Sulphuric Acid), HNO₃(Nitric Acid).
Strong vs. Weak Acids:
Strong acids completely ionise in aqueous solutions.
E.g., HCl ionises into H⁺ and Cl⁻ ions, fully dissociating its components.
Examples of strong acids: hydrochloric acid, sulphuric acid, nitric acid etc.
Weak acids do not fully ionise in aqueous solutions.
E.g., Acetic Acid ionises partially as follows: CH₃COOH(aq) ⇌ H⁺(aq) + CH₃COO⁻ (aq).
Examples of weak acids: acetic acid, citric acid, carbonic acid.
Classification of Acids:
Based on the number of H⁺ ions they release when dissolved in water:
Monoprotic acids release 1 proton.
Diprotic acids release 2 protons.
Polyprotic acids release 3+ protons.
Concentration of Acids:
Concentrated vs. Dilute:
Concentrated solutions have more of the substance per unit volume.
Dilute solutions have less of the substance per unit volume.
The substance is always added to water, not the other way around.
Indicators:
Blue Litmus paper:
Turns red in the presence of an acid.
Remains blue for neutral and basic solutions.
Universal indicator paper:
Acids turn red.
Neutrals turn green.
Bases turn violet.
The strip can be placed directly onto a wet substance or a few drops of the solution can be dropped onto the universal indicator using dropping equipment.
Bases are substances that release OH⁻ ions.
Bases are also known as alkalis when soluble in water.
Examples include NaOH(Sodium Hydroxide), KOH(Potassium Hydroxide), Ca(OH)₂(Calcium Hydroxide).
All alkali solutions have pH values greater than 7.
Bases react with acids to produce salts and water only in a neutralisation reaction.
Most metal oxides and ALL hydroxides are considered bases.
Metal oxides (e.g., magnesium oxide) are basic in nature.
Non-metal oxides (e.g., carbon dioxide) are acidic in nature.
Properties of Bases:
React with acids to produce salts and other products.
Turn red litmus paper blue, phenolphthalein pink, and keep bromothymol blue blue.
Have a pH greater than seven at standard conditions.
Salts are ionic compounds formed by the reaction of an acid with a base.
They contain positively charged metal ions and negatively charged non-metal ions.
Common salts include nitrates, sulphates, and chlorides.
Salts are categorised based on the negative ion they contain.
All salts can conduct electricity and have various uses.
Examples include ammonium chloride in flashlight batteries, ammonium sulphate in fertilisers, calcium carbonate in the extraction of iron, and potassium nitrate in gunpowder.
Acid rain is any form of precipitation with acidic components.
It results from emissions of sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere, which react with water, oxygen, and other chemicals to form sulphuric and nitric acids.
Sources of SO₂ and NOₓ include burning fossil fuels, vehicle emissions, manufacturing, and industrial processes.
Effects of acid rain include:
Harm to acid-sensitive wildlife.
Restriction of tree growth.
Episodic acidification.
Corrosion of buildings and infrastructure.
Health issues from inhaling sulphate and nitrate particles.
