Exploring Chemical Reactions

What are the four main types of chemical reactions?

• Redox

• Synthesis, Decomposition, Single Replacement, Double Replacement

• Photolysis

• Neutralization

• Combustion

Define a synthesis reaction and provide an example.

• The neutralization of an acid and a base: HCl + NaOH → NaCl + H₂O.

• The combustion of methane: CH₄ + 2O₂ → CO₂ + 2H₂O.

• The decomposition of water: 2H₂O → 2H₂ + O₂.

• An example of a synthesis reaction is the formation of water: 2H₂ + O₂ → 2H₂O.

What is a decomposition reaction? Give an example.

• The rusting of iron is a decomposition reaction.

• The combination of hydrogen and oxygen to form water is a decomposition reaction.

• The burning of wood is an example of a decomposition reaction.

• An example of a decomposition reaction is the breakdown of water (H2O) into hydrogen (H2) and oxygen (O2) gas when subjected to electrolysis.

Explain what a single replacement reaction is.

• A single replacement reaction is a process where two elements combine to form a compound.

• A single replacement reaction is a type of reaction that only occurs in gases.

• A single replacement reaction is a chemical reaction where one element replaces another in a compound.

• A single replacement reaction involves two compounds exchanging elements.

What characterizes a double replacement reaction?

• The breakdown of a compound into its individual elements.

• The formation of a single compound from two reactants.

• The transfer of electrons between two compounds.

• The exchange of ions between two compounds resulting in two new compounds.

How do you balance the chemical equation H2 + O2 → H2O?

• H2 + O2 → 2 H2O

• 2 H2 + 2 O2 → 2 H2O

• 2 H2 + O2 → 2 H2O

• H2 + O2 → H2O

What is the law of conservation of mass in relation to chemical equations?

• The total mass of products is irrelevant to the reactants.

• The total mass of reactants equals the total mass of products in a chemical reaction.

• Mass can be created or destroyed in a chemical reaction.

• The mass of reactants is always greater than the mass of products.

Describe an exothermic reaction and give an example.

• Combustion of methane (CH4) with oxygen (O2) is an example of an exothermic reaction.

• Rusting of iron

• Dissolving salt in water

• Photosynthesis of plants

What is an endothermic reaction? Provide an example.

• Respiration is an example of an endothermic reaction.

• Freezing water is an example of an endothermic reaction.

• Combustion is an example of an endothermic reaction.

• Photosynthesis is an example of an endothermic reaction.

How can you identify if a reaction is exothermic or endothermic?

• A reaction is exothermic if it produces light and endothermic if it produces sound.

• A reaction is exothermic if it releases heat and endothermic if it absorbs heat.

• Exothermic reactions always occur at low temperatures, while endothermic reactions occur at high temperatures.

• A reaction is exothermic if it absorbs heat and endothermic if it releases heat.