Flashcards in Unit 3 Deck (12)
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1
Chemical Reactions
Processes by which atoms of one or more substances rearrange to form new substance(s) (represented by chemical equations).
2
Evidence of Reactions
1. Temperature Change
• exothermic - energy released (hot)
• endothermic - energy absorbed (cold)
2. Change of State
• formation of precipitate - solid formed when two aqueous solutions react
• gas release (bubbling, effervescence)
• disappearance of a solid
3. Smell
4. Colour Change
• transparent, translucent, opaque
5. Other Energy Changes: Light, Sound, Electrical
3
Parts of Chemical Equations
• reactants (left side)
• products (right side)
• arrow symbol (yields or produces)
• state symbols (s, l, g, or aq subscripts)
• Stoichiometric coefficients
4
Types of Equations
1. Word Equation: Uses names of substances
2. Skeleton Equation: Uses formulas of substances (HOFBrINCl -g, g, g, l, s, g, g, are diatomic molecules with the subscript 2)
3. Balanced Equation: Uses coefficients in front of formulas to make atoms equal on both sides
5
Law of Conservation of Mass
In any chemical reaction, the mass of the reactant(s) is equal to the mass of the product(s) (balanced).
6
Synthesis
More than one reactant, one product formed.
A + B -> C
A and B are compounds or elements, C is always a compound.
Metal oxide (s) + Water (l) -> Metal Hydroxide (Base)
Nonmetal oxide (g) + Water (l) -> Acid
7
Decomposition
One reactant, more than one product formed.
A -> B + C
A is always a compound, B and C are compounds or elements.
8
Single Displacement (Cation Single Displacement)
An element on the Activity Series replaces another below it (ionic compound + element on Activity Series).
AX + B -> BX + A
If B is not higher than A on the Activity series, there is no reaction.
9
Single Displacement (Anion Single Displacement)
A halogen replaces another below it (ionic compound + halogen)
AX + Y -> AY + X
10
Double Displacement (Neutralization)
Two ionic compounds switch ions
Acid + Base -> Salt + Water
AX + BY -> BX + AY
11
Double Displacement (Gas Releasing Double Displacement)
An acid or base reacts with a salt to form an acid or base that decomposes into water and the corresponding gas.
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