Chemical Reactions – Combination, Decomposition & Energy Changes

20 fill-in-the-blank flashcards covering combination and decomposition reactions, exothermic vs endothermic changes, and key industrial and biological examples.

In a combination reaction, two or more reactants combine to give a __ product.

single

When calcium oxide (quick lime) combines with water, it produces __.

calcium hydroxide (slaked lime), Ca(OH)₂

Reactions that release heat along with products are called __ reactions.

exothermic

During whitewashing, Ca(OH)₂ slowly reacts with CO₂ in air to form __, giving walls a shiny finish.

calcium carbonate (CaCO₃)

What reaction is used for make cement

CaCO3 ——>Cao+ CO2

The common name of CaO is __.

quick lime

The common name of Ca(OH)₂ is __.

slaked lime

Thermal decomposition uses __ to break down a reactant.

heat energy

Heating CaCO₃ gives CaO and CO₂; this is an example of __ decomposition.

thermal

In the electrolysis of water, the volume of __ gas collected is double that of oxygen.

hydrogen

Exposure to sunlight turns white AgCl grey due to the formation of __ metal.

silver

Decomposition reactions that absorb energy are known as __ reactions.

endothermic

When ferrous sulphate crystals are heated, they decompose into ferric oxide, sulphur dioxide and __.

sulphur trioxide (SO₃)

Heating lead nitrate produces lead oxide, oxygen and brown fumes of __.

nitrogen dioxide (NO₂)

The breakdown of glucose with oxygen in body cells to release energy is called __.

respiration (an exothermic process)

In a decomposition reaction, a single reactant breaks down into __ or more products.

two

Decomposition driven by electricity is called __ decomposition.

electrolytic (electrolysis)

The energy that causes the decomposition of AgCl in photography is __.

light energy (sunlight)

A reaction in which heat is evolved is __ (exothermic/endothermic).

exothermic

In contrast to decomposition, a combination reaction results in __ product(s).

one (single)

The balanced equation for respiration is C₆H₁₂O₆ + 6O₂ → 6CO₂ + __ + energy.

6H₂O