Chemistry - SL Stoich Formulas & Equations

definitons + formulas and some bonding stuff

covalent molecular

* doesn’t conduct electricity
* soft
* low melting/boiling points

covalent network

* doesn’t conduct electricity
* hard substance
* no free moving charged particles
* high melting point/boiling point (many covalent bonds need to bebroken)

metallic bonding

* conducts electricity well
* malleable
* usually high melting/boiling points
* conducts heat well

ionic bonding

* metal and non-metal bonding
* transfer of electrons
* high melting/boiling point
* can conduct electricity **only in molten state**

covalent bonding

* non-Metals ONLY
* SHARING of electrons

Reactions in which elements burn in air or oxygen

* element + oxide (g) → elemental oxide (s)
* eg. Lithium (s) + Oxide (s) → Lithium Oxid (s)

Combustion

1. Hydrocarbon + Oxygen -→ Carbon Dioxide + Water
2. eg. ethene + oxygen → carbon dioxide (g) + water (l/g

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==**Reactive**== Metal + Water

* Metal + Water → Metal Hydroxide (aq)+ Hydrogen
* Potassium + Water → Potassium Hydroxide (aq) + Hydrogen (g)
* 2K (g)+ 2H2O (l) → 2KOH(aq) + H2 (g)

Metal + Acid (metal hydroxide or oxide)

* metal + acid → Salt + Water
* zinc + hydrochloric acid → Zinc chloride (aq) + Water (l)
* Zn + 2HCI → ZnCl2 (aq) + H2O (l)

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Acid + Base (carbonate/hydrocarbonate)

* Carbonate + Acid → salt + carbon dioxide + water
* calcium carbonate (s) + nitric acid (aq) → calcium chloride (aq) + Carbon dioxide (g) + water (l)
* CaCO3 (s) + HNO3 (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)

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Generally Soluble IONS (no exceptions)

* Na (+)
* NO3 (-)
* NH4 (+)
* K (+)
* CH3COO (-)

Generally Soluble - Cl (-), Br (-), I (-)

Exceptions: Ag (+) , Pb (+)

General soluble SO4 (2-), Cr2O7 (2-)

Exceptions:

* Pb (2+)
* Ba (2+)
* Ag (+)
* Ca (2+)

Generally @@insoluble -@@ CO3 (2-), PO4 (3-), S (2-)

Exceptions:

* NA (+)
* K (+)
* NH4 (+)

Generally Insoluble - OH (-)

Exceptions:

* Na (+)
* K (+)
* NH4 (+)
* ^^Ba (2+)^^
* ^^Ca (2+)^^
* Barium & Calcium are soluble with hydroxide ONLY

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NA

* Avagadros Constant
* 6.02 x 10^23

Significant figures:

How many dp’s are used in the final anser of addition & subtraction

no more dp’s than the term with the l**east number of dp’s**

Rounding should always be…

last step

Significant Figures:

How many dp’s does multiplication/division - final answer

same as the factor with the least number of figures

Definition of a mole

A __**mole**__ of substance is the __**amount of substance**__ that contains as many ^^specified particles^^ (ie. atoms, ions, molecules, electrons and so on) as there are atoms of carbon-12 in __**exactly**__ __12g__ __**carnon-12**__

1 mole =

* 6.02 x 10^23
* Avagadros Constant

number of moles

* number of particles/avagadro’s number
* n for moles is lowercase bc divided

number of particles

number of moles **x** avagadro’s number

n

no. of moles

N

no. of particles

m(g)

mass

M

Molar mass

Mass =

* number of moles x molar mass
* m(g) = n(mol) x M (gmol^-1)

Combined equation

* can find number of particles if given only. mass & vice versa