Studied by 2 peopleRate of reaction definition
a measure of how quickly a reactant is used up, or a product is formed.
To be successful when particles collide they need
the minimum activation energy
Rate of reaction equation
change in concentration, volume or mass/change in time
Volume units
dm³ (1 litre)
steepest part of graph
highest rate of reaction
gradient on a graph
rate of reaction
Effect steepness of curve
temperature, concentration, surface area and catalyst
effect height of curve
mass of product/reactant
collision theory
reactants in a solution must collide withe the particles on the solid surface area and have the activation energy for a reaction to occur and make the products
If a collision is not succsefull
they will bounce off each other
factors affecting rate
temperature, surface area, concentration, presence of a catalyst and pressure (of gas)
activation energy
the minimum amount of energy required to start a chemical reaction
equation to figure out rates on a graph
to find rate at a specific time draw a tangent then use that to figure out the gradient - this is the rate of reaction at that time
Average rate on a graph
product produced/reactant lost / time
methods for determining rates of reaction
mass lost with time, volume of gas produced or cross to disappear (if producing a solid)
metal carbonate reacts with acid to form
a salt, water and carbon dioxide
calcium carbonate (s) + Hydrochloric acid (aq) →
calcium chloride (aq) + water (l) + carbon dioxide (g)
CaCO₃ (s) + 2HCl (aq)→
CaCl₂ (aq)+ H₂O (l)+ CO₂ (g)
measuring the mass lost with time
Loses mass because the gas escapes the conical flask
cotton wool plug use
so the gas can escape but the other products (like the acid) can't
measuring gas produced measuring cylinder inaccurate
not all gas goes into the inverted measuring cylinder
Mg (s) + 2HCl (aq) →
MgCl₂ (aq) +H₂ (g)
CO₂ (g) + Ca(OH)₂ (limewater) (aq) →
CaCO₃ (aq) + H₂O (l) test for carbon dioxide
CuCO₃ (s) + 2HNO₃ (aq) →
Cu(NO₃)₂ (aq) + H₂O (l) + CO₂ (g)
Concentration of solutions affecting rate of reaction
Increasing the concentration of solutions means the particles are closer together, so there are more particles in a given volume. This increases the frequency of successful collisions which increases the rate of reaction.
Surface area of solids affecting rate of reaction
Increasing the surface area of solids means more particles, on the surface of the solid, are in contact with the other reactant making it so there is a higher frequency of successful collisions which increases the rate of reaction
Temperature affecting rate of reaction
Increasing the temperature means increasing the particles kinetic energy. this means that the particles move faster and collide more often. It also means more particles have the activation energy which increases the frequency of successful collisions and therefore the rate of reaction.
Catalyst affecting rate of reaction
Catalysts provide an alternative energy pathway with a lower activation energy without loosing mass (getting used up). This means a greater proportion of the particles have the activation energy which increases the frequency of successful collisions and therefore the rate of reaction.
mass rate of reaction graph
will end at a lower amount
Na₂S₂O₃ (aq) + 2HCl (aq) →
2NaCl (aq) + H₂O (l) + SO₂ (g) + S (s)
Catalyst
substances that speed up chemical reactions but aren't used up in the process - they are chemically unchanged
homogenous catalysts
in the same state as what they speed up (enzymes are proteins that speed up protein reactions)
How do catalysts find an alternative pathway
they (A) react with one product (B) and using that new product (AB) then reacts with the other product (C)
hydrogen peroxide (aq) →
water (l) + oxygen (g)
2H₂O₂ (aq) →
2H₂O (l) + O₂ (g)
Solute
A substance that is dissolved in a solution.
Solvent
the liquid in which a solute is dissolved to form a solution.
Solution
a mixture of solute and solvent
aqueous solution
a mixture of a solute and water
saturated solution
a solution that contains the maximum amount of dissolved solute
Solubility
The mass of a solute that will dissolve in 100g of water to form a saturated solution
Atom
the simplest particle of an element that can still be recognised as that element
Element
a substance which cannot be split into anything simpler by chemical means, and contains atoms of the same atomic number
Molecule
two or more atoms covalently bonded together
Relative atomic mass
The average mass of an atom relative to 1/12 of an atom of carbon-12
Anion
A negatively charged ion
cation
Positively charged ion
Oxidation
Gain of oxygen or loss of electrons
Reduction
Loss of oxygen or gain of electrons
Oxidising agent (oxidant)
Oxygen donor or electron acceptor
reducing agent (reductant)
oxygen acceptor or electron donor
Ionic type of bonding
Metal and non metal
Covalent type of bonding
Non-metal and non-metal
metallic bond
metal and metal
Nitrate
Sulfate
Hydroxide
Ammonium
Carbonate
Zinc valency
2
Silver valency
1
ionic bond
a strong electrical attraction between oppositely charged ions
Isoelectronic
atoms with the same electron configuration
ionic: dot cross diagram
A positive ion will be attracted to
any negative ion
An ionic bond between chloride ions and a sodium ion
Only one is formed by share of electrons, the other by forces
Why don't molecules of ionic compounds exist
because they are a giant structure (giant ionic lattice)
How can a negative ion bond to any positive ion
If they are close enough
properties of ionic compounds
high melting and boiling points, lack of electric conductivity when solid, brittle
High melting and boiling points of ionic compounds
The strong electrostatic force of attraction between the oppositely charged ions holds the structure together. It takes a huge amount of energy to break the ionic bonds to produce a molten compound.
Electric conductivity of ionic compounds
Do not react when solid because ions are fixed in place. Conducts electricity in molten or aqueous because ions can move carrying charge
Brittle ionic compounds
a small distortion of the lattice structure causes like charges to repel, and the compounds to break apart.
Electrostatic attraction in covalent bonds
the positively charged nuclei of both atoms are attracted to the negative electrons.
Covalent bonding
The sharing of a pair or multiple pairs of electrons holds the nuclei together in a covalent bond, overcoming the repulsion of the two nuclei
covalent bond
an electrostatic force of attraction between the nuclei of the atoms making up the bind and the shared pair of electrons
covalent compound structure
simple molecular
electricity in simple molecular
Do not conduct electricity
simple molecular boiling and melting point
low
Simple molecular at room temperature
liquids or gasses
Simple molecular when heated
The strong covalent bonds are not broken, it is the weak intermolecular forces of attraction that are broken
molecular mass increases
increases boiling and melting point
more electrons in a molecule
stronger molecular forces
Diamond structure type
Giant covalent
Graphite structure type
Giant covalent
c60 structure type
simple molecular
Diamond formula
c
Graphite formula
C
Buckminsterfullerene formula
C60
Diamond number of covalent bonds each C atom forms
4
Graphite number of covalent bonds each C atom forms
3
C60 number of covalent bonds each C atom forms
3
Diamond melting and boiling point
very high (higher than graphite)
graphite melting and boiling point
very high
c60 melting and boiling point
Low but relatively high for simple molecular
Diamond reason for melting and boiling points
carbon - carbon covalent bonds are very strong and require lots of energy to break
Graphite reason for melting and boiling points
Carbon - carbon covalent bonds in each layer must be broken but the IMF's between layers are easier to break
c60 reason for melting and boiling points
only have to break IMF's instead of covalent bonds
Diamond Electrical Conductivity
None
Graphite Electrical Conductivity
conductor
C60 Electrical Conductivity
None
Note
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