Energy

Seite 1

Chapter 7- Revision summary.

Topic

What

you need to know

What

you need to be able to do

Chemical and

physical change

·

Examples

of chemical change

·

Examples

of physical change

·

That

chemical change breaks bonds in reactants and makes new bonds in products

· Classify changes as chemical or physical

Endothermic and

exothermic

· Endothermic reactions take in heat

· Exothermic reactions give out heat

· Explosions are very fast exothermic

reactions

· Draw energy profile diagrams

· Use energy profile diagrams to work out if

a reaction is endothermic or exothermic

· Work out whether the reactants or

products have more energy in their bonds based on the energy profile

Equations

· Reactants go on the left

· Products go on the right

· An arrow signifies a chemical reaction

· write word equations from a description

of the reaction

· Write symbol equations when provided with

the formula

· Balance symbol equations so that there

are the same number of each type of atom on each side

Conservation of

mass

· That mass is neither gained or lost in a chemical

reaction

· That experimental error can cause the

perception that mass changes

· Identify experimental errors that can

cause it to appear that mass is gained or lost

· Explain why the conservation of mass law

is true by explaining that chemical reactions rearrange atoms but do not

create or destroy them

Acids and bases

· Acids have a pH

· Bases have a pH 7-14

· Neutral substances have a pH of 7

· Acidic solutions contain excess hydrogen

ions

· Basic solutions contain excess hydroxide

ions

· Write equations for reactions involving

acids and bases (Acid + base à salt and water)

· Use the pH of a substance to identify it

as acid, basic or neutral

· Explain that neutralisation reactions

balance the hydrogen / hydroxide ion concentration and bring the pH closer to

7

Combustion

· Combustion reactions involve exothermic

reactions with oxygen

· The products of burning fuels are carbon

dioxide and water

· Write equations for combustion reactions

· Draw energy profile diagrams for

combustion reactions

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