Difference between revisions of "Rate of Reaction"

Revision as of 12:28, 16 January 2019

Key Stage 4

Meaning

Rate of reaction is a measure of how quickly the reactants react to create the products.

About the Rate of Reaction

The longer the time taken for a reaction the lower the rate of reaction. The shorter the time taken for a reaction the higher the rate of reaction.

High rates of reaction are important to in industries where a lot of products are needed in a short amount of time. This can save money.

Low rates of reaction are important in materials that corrode with chemicals in the environment. This allows them to last a long time before destroyed by Oxidation or chemical weathering.

Examples


Rusting has a low rate of reaction.	Burning Magnesium ribbon has a high rate of reaction.

Determining the Rate of Reaction

There are two approaches to finding the rate of reaction for some chemicals.

Find out how quickly the reactants are used up.
Find out how quickly new products are made.

Continuously Measuring Volume of Gas

For reactions which give off a gas the volume of gas produced can be measured throughout an experiment to find the rate of reaction.


This diagram shows a possible setup for measuring the gas given off during an experiment.

Continuously Measuring the Mass

For reactions which give off a gas the mass of reaction mixture can be measured throughout an experiment to find the rate of reaction.


This diagram shows a possible setup for measuring the mass of the reaction mixture during an experiment.

Continuously Measuring the Opacity

For reactions in which the reactants are in a transparent solution but the products form an insoluble precipitate that is opaque then the opacity can be measured.


This diagram shows a possible setup for identifying when a mixture becomes opaque during a reaction by drawing a black cross on a white tile and observing until the cross can no longer be seen.

Rate of Reaction from Graphs

On a graph with time on the x-axis and the amount of reactant or product on the y-axis the rate of reaction can be seen from the gradient.


The steep positive gradient shows a high rate of reaction as the gas is produced more quickly at the start of the reaction.	The steep negative gradient shows a high rate of reaction as the gas is being lost more quickly at the start of the reaction.	The steep negative gradient shows a high rate of reaction as the precipitate is formed more quickly at the start of the reaction.

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 | style="height:20px; width:200px; text-align:center;" |This [[diagram]] shows a possible setup for identifying when a [[mixture]] becomes [[opaque]] during a [[Chemical Reaction|reaction]] by drawing a black cross on a white tile and [[observe|observing]] until the cross can no longer be seen.
+|}
+===Rate of Reaction from Graphs===
+On a [[graph]] with [[time]] on the [[x-axis]] and the amount of [[reactant]] or [[product]] on the [[y-axis]] the '''rate of reaction''' can be seen from the [[gradient]].
+{| class="wikitable"
+|-
+|[[File:GasVolumeTimeReactionSketchGraph.png|center|200px]]
+|[[File:MassTimeReactionSketchGraph.png|center|200px]]
+|[[File:OpacityTimeReactionSketchGraph.png|center|200px]]
+|-
+| style="height:20px; width:200px; text-align:center;" |The steep positive [[gradient]] shows a high '''rate of reaction''' as the [[gas]] is [[product|produced]] more quickly at the start of the [[Chemical Reaction|reaction]].
+| style="height:20px; width:200px; text-align:center;" |The steep negative [[gradient]] shows a high '''rate of reaction''' as the [[gas]] is being lost more quickly at the start of the [[Chemical Reaction|reaction]].
+| style="height:20px; width:200px; text-align:center;" |The steep negative [[gradient]] shows a high '''rate of reaction''' as the [[precipitate]] is formed more quickly at the start of the [[Chemical Reaction|reaction]].
 |}