5. PRO Chemical Changes: simplify๏ƒ

Below is a set of PRO explanations.

Rewrite each explanation using the PRO structure, ensuring that the sentence starters are as simple as possible.

  1. Vinegar and baking soda

According to the particle model, acids react with carbonates to produce carbon dioxide gas.
At the particle level, hydrogen ions react with carbonate ions, forming carbon dioxide particles that move freely.
Consequently, fizzing is observed as carbon dioxide gas escapes.

  1. Hand warmer activation

The governing principle is that some chemical reactions are exothermic.
At the sub-microscopic level, iron particles react with oxygen, releasing energy as bonds are rearranged.
Thus, the hand warmer increases in temperature.

  1. Lead nitrate and potassium iodide

According to the established particle model, some ionic compounds are insoluble in water.
At the particle level, lead ions combine with iodide ions to form solid lead iodide particles.
Hence, a yellow precipitate is observed.

  1. Rusting of iron

The underlying mechanism is that iron reacts with oxygen in the presence of water.
At the particle level, iron atoms lose electrons to oxygen, forming iron oxide compounds.
Consequently, rust forms on the iron surface.

  1. Burning magnesium strip

According to the relevant scientific theory, combustion is a rapid reaction with oxygen.
At the sub-microscopic level, magnesium particles react with oxygen, releasing a large amount of energy.
Thus, a bright white flame and magnesium oxide are produced.

  1. Ignition of methane

The principle governing this behaviour is that reactions require activation energy.
At the particle level, the spark provides energy to break initial bonds in methane and oxygen particles.
Hence, methane ignites and undergoes combustion.

  1. Heating copper carbonate

According to the established model, heating can cause thermal decomposition.
As particle kinetic energy increases, copper carbonate particles break apart into copper oxide and carbon dioxide particles.
Consequently, a colour change occurs and gas is released.

  1. Glucose production in plants

According to the accepted scientific model, photosynthesis converts light energy into chemical energy.
At the particle level, light energy drives reactions that rearrange carbon dioxide and water particles into glucose.
Ultimately, glucose is produced to provide energy for the plant.

  1. Magnesium in hydrochloric acid

In this context, reactive metals displace hydrogen from acids.
At the sub-microscopic level, magnesium particles lose electrons to hydrogen ions, forming hydrogen gas particles.
Consequently, fizzing is observed as hydrogen gas bubbles form.

  1. Green coating on copper

The phenomenon can be attributed to slow chemical reactions with atmospheric substances.
At the particle level, copper reacts with oxygen, water and carbon dioxide to form new compounds.
Thus, a green coating develops on the copper surface.

  1. Silver nitrate and sodium chloride

According to the particle model, a precipitate forms when an insoluble product is produced.
At the sub-microscopic level, silver ions and chloride ions combine to form solid silver chloride particles.
Consequently, a white precipitate is observed.

  1. Combustion of ethanol

The governing principle is that fuels undergo combustion in oxygen.
At the particle level, ethanol particles react with oxygen particles, forming carbon dioxide and water while releasing energy.
Thus, heat and light are produced.

  1. Bright white flame from magnesium

According to the particle model, energy released in reactions can excite electrons.
As electrons gain energy, they emit visible light as they return to lower energy states.
Ultimately, an intense bright white flame is observed.