Questions and Answers
A chemical reaction occurs when milk is left at room temperature for a long time.
True
What is formed when magnesium burns in air?
What do we call the substances that undergo change during a chemical reaction?
Reactants
According to the Law of Conservation of Mass, mass is neither created nor ______ in a chemical reaction.
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Which of the following is the correct skeletal equation for the burning of magnesium?
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Match the following terms with their definitions:
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In a chemical reaction, what does the term 'products' refer to?
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The process of respiration is an example of a chemical change.
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What is produced when sodium reacts with water?
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The Law of Conservation of Mass states that matter can be created or destroyed during a chemical reaction.
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Write the balanced equation for the reaction of sodium hydroxide with hydrochloric acid.
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In the reaction of calcium oxide with water, the product is ___.
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Match the following reactions with their type:
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Which of the following statements is true regarding skeletal equations?
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A reaction produces a gas and an aqueous solution, thus the system's mass will change.
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What is formed when barium chloride reacts with sodium sulfate?
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What type of reaction occurs when two or more substances combine to form a single product?
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Exothermic reactions absorb heat from the surroundings.
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What is the special name of the process during which glucose combines with oxygen to produce energy in our body?
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Match the following reactions with their descriptions:
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The reaction that takes place during the burning of coal can be represented as ___ + O2(g) → CO2(g).
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Which of the following is NOT a product of the combustion of natural gas?
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The law of conservation of mass states that mass can be created or destroyed in a chemical reaction.
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Identify one common exothermic reaction.
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Study Notes
Chemical Reactions and Equations
- Chemical reactions involve the breaking and forming of bonds between atoms to create new substances.
- Atom identity and number remain constant; they do not change into other elements or disappear.
- Balanced equations must include state symbols (e.g., solid, liquid, gas, aqueous).
Example Reactions
- Hydrogen + Chlorine → Hydrogen chloride (HCl)
- Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
- Sodium + Water → Sodium hydroxide + Hydrogen
Balancing Chemical Equations
- Barium chloride solution reacts with sodium sulphate to form insoluble barium sulphate and sodium chloride solution:
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq) - Sodium hydroxide solution reacts with hydrochloric acid to produce sodium chloride solution and water:
NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)
Types of Chemical Reactions
- Combination reactions occur when two or more substances combine to form a single product.
- Example of combination reaction:
CaO(s) + H₂O(l) → Ca(OH)₂(aq) - Exothermic reactions release heat during the formation of products.
Exothermic Reaction Examples
- Burning of coal: C(s) + O₂(g) → CO₂(g)
- Formation of water: 2H₂(g) + O₂(g) → 2H₂O(l)
- Burning of natural gas: CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g)
- Respiration is an exothermic process where glucose combines with oxygen:
C₆H₁₂O₆(aq) + 6O₂(aq) → 6CO₂(aq) + 6H₂O(l) + energy
Activities Demonstrating Reactions
- Burning magnesium ribbon produces magnesium oxide, releasing heat and light.
- Observations include a dazzling white flame and formation of a white powder.
Everyday Chemical Changes
- Fermentation of grapes, cooking, digestion, respiration, and milk spoiling are daily life examples of chemical changes indicating a chemical reaction has occurred.
Studying That Suits You
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Description
Test your knowledge on balancing chemical equations and understanding state symbols in reactions. This quiz will cover various chemical reactions including those involving sodium, barium, and chlorine. Perfect for chemistry students looking to sharpen their skills in chemical equations.
