Chemistry

Collision Theory

particles must collide with sufficient energy and proper orientation for a chemical reaction to occur, with the rate of reaction depending on the frequency and effectiveness of collisions

Activation Energy

The energy needed to break the intramolecular forces between reactant molecules for a chemical reaction to take place; higher activation energy requires more energy for the reaction to proceed.

Catalysts

Substances that speed up reactions by lowering the activation energy needed for the reaction to occur, without being consumed or chemically altered in the process.

what are the relating factors which increase rate of reaction

• frequency of collision (more = faster)

• effective collisions (occurring with sufficient energy)

• effective collisions (orientation)

How are reaction rate and collision theory related to each other? Use collision theory to answer your question

Reaction rate and collision theory are closely related as collision theory explains that for a reaction to occur, reactant molecules must collide with sufficient energy and proper orientation. The reaction rate depends on the frequency and effectiveness of these collisions. Factors such as higher reactant concentrations, increased temperatures, presence of catalysts, and greater surface area enhance the effectiveness of collisions, thereby increasing the reaction rate.

surface area

If there is a greater surface area available for a reactant to access, this increases the chances of a collision to occur. Therefore since the frequency of these collisions are increased, the rate of reaction will also increase in speed.

concentration

If there is a greater concentration, then there are more reactant particles moving around. This therefore increases chances of collisions to occur between the particles, therefore speeding up the rate of reaction in the experiment.

Temperature

If there is a higher temperature than the average speed and kinetic energy of the reactant molecules are increased. This increases the chance of collisions because as more molecules move faster, the number of molecules with sufficient energy increases, resulting in a faster formation of products.

systematic error

a consistent error which affects the results

• constant in magnitude

• usually due to observer, instrument or environmental conditions

• e.g. debris left in a test tube causing mass to be 0.1 g more than it should

How to prevent:

• use calibrated equipment

random error

inconsistent error

• e.g reaction time to starting a timer

How to prevent:

• perform experiment multiple times

• discard outliers

• average results

Accuracy (systematic errors)

accuracy is how close the results of an experiment is to its true theoretical value

improve by:

• minimising systematic errors (e.g. zeroing scales)

• use better equipment

  • more sensitive/smaller increment scale (mm is more accurate than cm)

Reliability (random errors)

Reliability is the consistency of an experiment and whether or not it can be replicated with the same results.

improve by:

• minimising random errors

• having controlled variables

• discard outliers, average results

sulfate

SO₄²-

ammonium

NH₄⁺

acetate

CH₃COO-

nitrate

NO₃-

hydroxide

OH¯

carbonate

CO₃²⁻

phosphate

PO₄³⁻

peroxide

O₂²⁻

Heat and temperature

Temperature is a measure of the average kinetic energy of the atoms or molecules in the system

Heat is the transfer of thermal energy between two bodies at different temperatures. hotter transfers to colder

Zero order

rate is not affected by the concentration is a reactant, when you double the concentration stays the same

First Order

rate is proportional to the concentration of a reactant, when you double the concentration the rate also doubles

Second order

rate is proportional to the square of the concentration of a reactant, when you double concentration the rate goes up 4 times