Y10 Chemistry P.2

Second booklet

Theory of Collision

For chemical reactions to occur, particles must first collide with each other, with sufficient activation energy and in the correct orientation

Collide

Particles must first physically come into contact with each other

Sufficient Activation Energy

Particles must collide at great enough speeds to break existing chemical bonds for the reaction to occur

Correct Orientation

Particles must align in the exact direction to guarantee correct atoms make contact

Factors influencing rate of chemical reaction

Temperature, Concentration, Surface Area, Agitation, Catalyst

Temperature

When increased, kinetic energy of reactant particles also increases to meet the sufficient activation energy (increasing rate of successful collisions), further speeding up the reaction as the particles move faster

Concentration

An increase in the number of particles per unit volume decreases the distance between particles, increasing the rate of collisions and hence the reaction rate

Agitation

Stirring increases the number of reactant particles exposed to each other at the same time, further introducing collisions and speeding up the reaction rate

Surface Area

Increased spaces of contact to each other through increasing the particles (typically achieved through grinding into powders, e.g. mortar/pestle)

Catalyst

Provide an alternative lower activation energy reaction pathway without being consumed in the process, and can hence be re-used to speed up other reactions

Decomposition

Where a single reactant is broken down into two or more products (e.g. H₂O₂ → H₂O + O₂)

Neutralisation

Acid (produce Hydrogen ions in water) + Base (receives protons) → Salt + Water

React to form water and salt as the products (e.g. HCl₂₍aq₎ + NaOH₍aq₎ → NaCl₍aq₎ + H₂O

Acid + Carbonate

Need to balance equation: Acid + Carbonate → Salt + Water + Carbon dioxide

Produces salt, water and carbon dioxide (e.g. vinegar and baking soda producing CO₂ bubbles)

Acid + Hydrogencarbonate (bicarbonate)

Acid + Hydrogencarbonate → Salt + Water + Carbon dioxide

Produces salt, water and carbon dioxide (e.g. 2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂)

Acid + Metal

Metal + Acid → Salt + Hydrogen gas (MASH)

Produces salt + hydrogen gas (e.g. Mg + 2HCl → MgCl₂ + H₂₍g₎ )

Precipitation

Chemical reaction in aqueous solution; two soluble ionic compounds mix to form insoluble solid product (precipitate)

Mole (chemistry)

Avorgado's constant: 6.022×10²³ particles (represents number of molecules in substance, found by multiplying atomic number)