Rates of reaction C6
- Created by: H@r/3y
- Created on: 18-02-19 11:40
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- Rates of reaction
- Rate of chemical reaction is how fast the reactants are changed to products
- Slow reaction: iron rusting or chemical weathering
- Medium speed reaction: metal magnesium causing bubbles in acid
- Fast reaction: burning or explosions
- Graph (Product formed over time)
- Steeper the line faster the RoR (rate of reaction) lines becomes less steep as reactants are used up
- Quickest reactions have steepest line and become flat in the quickest time
- Collision theory (rate of reaction depends on:...)
- Collision frequency: how often they collide, more collisions faster the reaction
- Energy transferred: particles need to collide with enough energy for it to be successful -activation energy (minimum energy needed to break bonds)
- Depends on 1. temperature 2. con-centration. 3. Pressure 4.surface area 5. Catalyst
- Temperature : increase temperature means particles move faster as they have more energy so they collide more frequently with enough energy
- Con-centration and pressure: more concentratedmeans more particles in the same volume (same for pressure but gases) mean more frequent collisions
- Surface area: breaking a reactant from a solid into smaller pieces increases surface area, meaning for the same volume of solid there’s now more area for collisions to occur
- Catalyst: -speeds up reaction without being used up or affecting the overall equation- they decrease activation energy by providing a alternative pathway with lower activation energy so more successful collisions with enough energy
- Measuring RoR
- Rate of reaction is amount of reactant used or amount of product formed over time
- Reactant/product is gas = cm^3 or a solid = g. Time in s. Unit for rate is either cm^3/s or g/s or for moles mol/s
- Reactant/product is gas = cm^3 or a solid = g. Time in s. Unit for rate is either cm^3/s or g/s or for moles mol/s
- Can be measured in three different ways: 1. Precipitation or colour change 2. Change in mass 3. Volume of gas is given off
- 11. Colour change/ precipitation = visual change from transparent to opaque solution if product precipitates. From coloured to colourless solution (or vice versa)
- Measure how long it takes for a cross to become invisible through the solutionn or how long it takes for colour change
- 2. Change in mass= reactions the produce a gas means speed of reaction can be measured using a mass, quicker it takes for the mass balance to drop faster the reaction
- Take measurements at regular intervals to plot a graph, it’s the most accurate method however the gas is released into the room
- 3. Volume of gas= uses a gas syringe to measure volume of gas given off. More gas in given time interval faster reaction.
- Take measurements at regular intervals to plot a graph, however if reaction is too vigorous the plunger will blow out of the end of the syringe
- 11. Colour change/ precipitation = visual change from transparent to opaque solution if product precipitates. From coloured to colourless solution (or vice versa)
- Rate of reaction is amount of reactant used or amount of product formed over time
- Rate of chemical reaction is how fast the reactants are changed to products
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