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What is a chemical reaction?
What is a chemical reaction?
A chemical process in which new substances with new properties are formed due to re-arrangement of atoms.
What are the two main types of changes that can occur in a chemical reaction?
What are the two main types of changes that can occur in a chemical reaction?
Physical changes are reversible.
Physical changes are reversible.
True
Give two examples of physical changes.
Give two examples of physical changes.
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Give three examples of chemical changes.
Give three examples of chemical changes.
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Why do we rub a magnesium ribbon with sand paper before burning it?
Why do we rub a magnesium ribbon with sand paper before burning it?
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Why should we keep burning magnesium away from our eyes?
Why should we keep burning magnesium away from our eyes?
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What do you observe when magnesium ribbon burns in air?
What do you observe when magnesium ribbon burns in air?
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Write the balanced chemical equation for the reaction between magnesium and oxygen.
Write the balanced chemical equation for the reaction between magnesium and oxygen.
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What type of reaction is Pb(NO3)2 + 2KI -> 2KNO3 + PbI2?
What type of reaction is Pb(NO3)2 + 2KI -> 2KNO3 + PbI2?
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Why is the reaction Pb(NO3)2 + 2KI -> 2KNO3 + PbI2 called a precipitation reaction?
Why is the reaction Pb(NO3)2 + 2KI -> 2KNO3 + PbI2 called a precipitation reaction?
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Write the balanced chemical equation for the reaction between zinc and sulfuric acid.
Write the balanced chemical equation for the reaction between zinc and sulfuric acid.
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What is the observation for the reaction between zinc and sulfuric acid?
What is the observation for the reaction between zinc and sulfuric acid?
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What is the name of the gas evolved in the reaction between zinc and sulfuric acid?
What is the name of the gas evolved in the reaction between zinc and sulfuric acid?
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What is the test for hydrogen gas?
What is the test for hydrogen gas?
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What is an unbalanced chemical equation?
What is an unbalanced chemical equation?
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What is a balanced chemical equation, and which law governs the balancing of equations?
What is a balanced chemical equation, and which law governs the balancing of equations?
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Study Notes
Chemical Reactions and Equations
- Chemical Reactions: A process where new substances with different properties are formed due to atoms rearranging. Changes can be physical or chemical.
- Physical Change: A temporary change where new products aren't formed, only properties like color, shape, or size change. These changes are reversible.
- Chemical Change: A permanent change, involving a new substance with different properties. The reactant composition is irreversibly changed. New products are formed and are chemically different. These changes are irreversible.
- Examples of Chemical Changes: Respiration, Digestion, Plant and animal growth, Rusting, Burning of magnesium.
- Examples of Physical Changes: Melting of wax, Boiling water.
Activity 1.1 - Burning of Magnesium Ribbon
- Procedure: Clean a magnesium ribbon with sandpaper to remove the oxide layer.
- Purpose: Removing the oxide layer enables complete reaction with oxygen.
- Observation: When burned, magnesium reacts rapidly with air, producing a bright, white light, and forming magnesium oxide (a white powder).
- Importance: Magnesium is a highly reactive metal.
Activity 1.2 - Lead Nitrate Reacts with Potassium Iodide
- Procedure: In a reaction test between lead nitrate and potassium iodide, the two are mixing together. A reaction between the two gives off a precipitate.
- Observation: The mixture forms a yellow precipitate (lead iodide), and potassium nitrate remains in solution.
- Reaction Type: Double displacement or precipitation reaction. This is when two ionic compounds exchange ions to produce two new compounds.
- Significance: This is an example of a chemical reaction where a solid substance (precipitate) forms from mixing two solutions.
Activity 1.3 - Action of Sulphuric Acid on Zinc Granules
- Procedure: Zinc granules are reacted with sulfuric acid in a controlled environment.
- Observation: Bubbles of a gas (hydrogen) are formed on the zinc surface. The gas is evolved, and fizzing or effervescence is visible.
- Reaction Type: Displacement reaction.
- Product: Hydrogen gas is released as zinc displaces hydrogen in sulfuric acid; zinc sulfate is formed as a product as sulfuric acid is reacted with the zinc.
- Testing the Gas: The hydrogen gas, when ignited, produces a distinctive 'pop' sound, which confirms its identity.
Writing Chemical Equations and Balancing Equations
- Chemical Equation: A shorthand representation of a chemical reaction using symbols and formulas.
- Unbalanced Equation: A chemical equation where the number of atoms of each element is not equal on both sides of the equation.
- Balanced Equation: A chemical equation where the number of atoms of each element is equal on both sides of the equation (obeying the law of conservation of mass).
Other Observations
- Changes in color: Chemical reactions can result in changes in the colors of the substances.
- Evolution of gas: The formation of gas bubbles is another indicator of chemical reactions.
- Change in temperature: Chemical reactions can either release or absorb heat, so temperature changes are important indicators.
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Description
This quiz explores the different types of chemical reactions and equations. You will learn about physical and chemical changes, their characteristics, and examples. Engage with practical examples and activities to enhance your understanding of these fundamental concepts in chemistry.
