chemical reactions

chemical reactions

chemical reactions

process where the reactants are rearranged at a molecular level. At least one new product is formed.

classifying helps chemists understand how chemical reactions work

evidence of chemical change

• colour change

• temperature change

• pH change

• gas (bubbles) forming

• precipitate (solid) forming

• new odour

law of conservation of mass

mass is neither created or destroyed in chemical reactions, it is only transferred or transformed

decomposition reactions

a single reactant breaks apart to form several products; reactant decomposes

general form of a decomposition reaction

XY → X + Y

decomposition reactions example

• Soft drinks contain dissolved carbonic acid (H₂CO₃).

• When carbonic acid decomposes, it forms water (H₂O) and bubbles of carbon dioxide gas (CO₂).

Synthesis (Combination) Reactions

when 2 reactants combine to form a single product

general form of synthesis reactions

X + Y → XY

synthesis reaction example

• hydrogen gas (H₂) and chlorine gas (Cl₂) are combined to form hydrogen chloride gas (HCl)

Double Replacement (Precipitation) Reactions

• two salt solutions (each consisting of an anion bonded to a cation) mixed together; they swap their partners.

• when the anions and cations swap, they may react to form a solid; solid is called a precipitate

general form of precipitation reaction

AB + CD → CB AD

single replacement reaction

when an element is replaced by another that is part of a compound

general form of single replacement reaction

A + BC → B + AC

Acids

• Contain Hydrogen.

• Have a sour taste.

• pH less than 7.

• Can range from an irritant to highly corrosive.

• Found in many foods and even in our stomach

Bases

• Taste bitter.

• pH greater than 7.

• Feel slippery.

• Found in cleaning products.

• Can be just as dangerous as acids.

Acid + Base reactions

• produce salt and water.

• salt is decided by the atoms present in the acid and the base.

Acid + Base form

Acid + Base → Salt + Water

acid + base examples

• Hydrochloric Acid + Sodium Hydroxide → Sodium Chloride + Water

• Sulfuric Acid + Magnesium Hydroxide → Magnesium Sulfate + Water

Acid + metal reactions

• produce salt and hydrogen.

• The salt is decided by the atoms present in the acid and the base.

Acid + Metal form

Acid + Metal → Salt + Hydrogen

acid + metal examples

• Hydrochloric Acid + Sodium → Sodium Chloride + Hydrogen

• Nitric Acid + Copper → Copper Nitrate + Hydrogen

acid + carbonate examples

• produce a salt, water and carbon dioxide.

• The salt is decided by the atoms present in the acid and the base.

acid + carbonate form

Acid + Carbonate → Salt + Water + Carbon Dioxide

acid + carbonate examples

• Hydrochloric Acid + Sodium Carbonate → Sodium Chloride + Water + Carbon Dioxide

• Phosphoric Acid + Tin Carbonate → Tin Phosphate + Water + Carbon Dioxide