7C BB & Reactions

Choose all of the answers which are a sign of a CHEMICAL REACTION?

• A solid changes to a liquid

• fizzing

• a mixture gets hotter

• a solid dissolves into a liquid

Choose all of the answers which are a sign of a PHYSICAL CHANGE?

• A gas changing to a liquid

• a metal burning

• a liquid starting to bubble

• two liquids making a solid

What happens in an OXIDATION reaction?

• a metal burns with a bright white light

• breathing

• oxygen is released when the solid is heated

• oxygen is added

What happens in a THERMAL DECOMPOSITION reaction?

• a metal burns

• a large molecule breaks down into smaller molecules on heating

• a solid / powder changing colour when heated

• wood rotting in hot weather

Why do some substances NOT REACT (ie no reaction)?

• they are already burnt

• they hve not been heated enough

• they are already in a stable form

• they are non-metals

What happens in a CHEMICAL REACTION?

• a substance gets burnt - oxygen added

• chemical bonds are made and/or broken

• substances change colour

• a substance / chemical changes into a different state of matter

What is a REVERSIBLE REACTION?

• a chemical reaction that can be changed back

• when a reaction goes the wrong way

• a white powder goes blue

• a blue liquid changes to a blue solid

What happens in a NEUTRALISATION reaction?

• a metal fizzes in an acid

• we put lime into the soil

• the acidic / alkaline effects of a solution are cancelled out

• when acid rain corrodes buildings

What happens in a DISPLACEMENT reaction?

• an element changes places with one part of a compound

• a chemical changes from one colour to another colour

• a chemical (eg Magnesium) burns to make a new substaces (eg Magnesium Oxide)

• a substance loses carbon dioxide to become a smaller molecule

A reaction is carried out using a CARBONATE (eg copper carbonate)... What would be released?

• oxygen

• hydrogen

• water vapour

• carbon dioxide