Chemistry Flashcards
Reactant
Substance(s) that take part in a chemical reaction
Product
Substances produced in a chemical reaction
Word equation
Shows names of chemicals that are reactants and products
Chemical equation
Shows chemical formulas for all reactants and products. Must be balanced on each side, i.e. same amount of H atoms
Subscript
Tells us how many atoms there are in the molecule
Coefficient
Tells us how many molecules there are
Law of conservation of mass
In a chemical reaction, mass (atoms) can’t be created or destroyed, therefore what goes into the reaction must come out, and the mass must be equal.
Balancing a chemical equation
Each element must have equal atoms on each side. Can’t change subscripts.
Molecules store energy in the form of
Chemical potential energy, so in a chemical reaction energy changes
Exothermic reaction
Energy is released, and feels hot. More energy in reactants than products
Endothermic reaction
Energy is absorbed, and feels cold. More energy in products than reactants
Combustion
Reaction when things burn. Needs oxygen and fuel. Exothermic.
Hydrocarbons
Readily undergo combustion. oxygen+ fuel into carbon dioxide + water
Incomplete combustion
Not enough oxygen, forms C or CO instead of CO(2) eg. yellow flame on bunsen burner
Respiration
combustion in cells of living things, exothermic
Oxidation
metal + oxygen into metal oxide
Corrosion
When iron undergos oxidation. Produces rust. Needs water. iron + oxygen + water into iron(III) oxide
Precipitation reaction
When a soluble compound is mixed with another soluble compound and forms insoluble compound. aq + aq into aq + s
Reactants swap places. Check solubility on table to see if a precipitation reaction occurs.
Decomposition reaction
XY into X + Y
Thermal decomposition
When heat is needed to decompose a substance
Metal oxide decomposition
Some metal oxides decompose to form metals. This was used in Bronze age, when copper oxides were heated to form Bronze.
Displacement reaction
When one metal displaces (swaps places) with another metal i.e. AB + C into A + BC. Only happens when C is more reactive than A.
(re)activity series
List of metals in decreasing order of reactivity, or decreasing ability to lose outer-shell electrons. Moving up, reactivity is stronger, electrons are less stable, less chance of finding them in their natural state, extraction is harder and more expensive as compounds are stronger
collision theory
reactants must collide, sufficient energy, right direction/orientation
Factors that change rate of reaction
temperature, concentration, surface area, catalysts
Temperature in rate of reaction
atoms move faster, so collide more frequently and with more energy
Concentration in rate of reaction
More particles to collide with each other, so collide more
Surface area in rate of reaction
More particles open, more particles reacting at the same time
Catalyst in rate of reaction
chemicals that speed up rate of reaction but aren’t used up, written above arrow but not in chemical equation. Reduces energy needed for reaction, makes it easier for a successful reaction
