how fast

the rate of a chemical reaction is the increase in concentration of products, or the decrease in concentration of reactants, per unit time. - It describes how quickly a reaction happens. - compares how much change occurs in a fixed amount of time.

rate of reaction = increase in product concentration / time taken or rate = Δ[P] / Δt

rate takes the reciprocal value of time, so is expressed per unit time or, in SI units, per second (symbol = s-1). - rate is change in concentration per unit time.

rate of reaction = decrease in reactant concentration / time taken or rate = −Δ[R] / Δt The negative sign is used because reactant concentration decreases, but rate is expressed as a positive value.

rate of reaction = increase in product concentration / time taken rate = Δ[P] / Δt

Product concentration increases over time as reactants are converted into products. The curve usually becomes less steep as the reaction slows down.

Reactant concentration decreases over time as it is used up. The curve usually becomes less steep as the reaction slows down.

The gradient shows the change in concentration per unit time, which is the rate of reaction.

The reaction with the steeper curve has a faster rate because the reactant concentration is decreasing more quickly.

Because the gradient is not constant, so the rate can only be measured at a particular time by drawing a tangent to the curve. - the graphs are curves and not straight lines

Draw a tangent at the specified time, calculate its gradient using change in concentration divided by change in time, then express the rate as a positive value.

Reactant concentration decreases over time, so the change in concentration is negative.

No. The rate is not constant; it is greatest at the start and decreases as the reaction proceeds.

By convention, rate is always expressed as a positive value, so the negative gradient is converted to a positive rate.

Reactant concentration is highest at the start

Reactant concentration decreases as reactants are converted into products.

The initial rate is the rate at the start of the reaction, found by drawing a tangent to the curve at t = 0.

Draw the tangent as long as reasonably possible so that the change in concentration and change in time are as large as possible.

Initial rates are useful for comparing reactions under different conditions and analysing the effect of concentration on rate.

The rate of a chemical reaction is the increase in concentration of products or the decrease in concentration of reactants per unit time. It can be calculated from the gradient of a concentration-time graph. For curved graphs, a tangent must be drawn at a specific time. Rate is always expressed as a positive value and has units of mol dm⁻³ s⁻¹. The rate is greatest at the start and decreases as the reaction proceeds.

Collision theory states that species react as a result of collisions with sufficient energy and proper orientation.

The kinetic molecular theory states that particles in substances move randomly because of the kinetic energy they possess. - because of this particles in a substance have a range of kinetic energy values rather than one single value. - a conveninet way to describe this is take the average of kinetic energy of particles

Temperature in kelvin (absolute temperature) is directly proportional to the average kinetic energy of the particles in a substance.

Increasing temperature increases the average kinetic energy of the particles. - Heating supplies extra energy to the particles, increasing their average kinetic energy and therefore increasing temperature.