Chemical reactions don't all happen at the same speed -...
Chemistry310 views·Updated 17 Jul 2026·2 pagesUnderstanding Reaction Rates for AQA GCSE Chemistry
M
Mary!@mfr22
1
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Five Key Factors That Control Reaction Speed
Think of reaction rate like the speed limit on a motorway - certain conditions can make reactions zoom along or crawl at a snail's pace. There are five main factors that control how quickly chemical reactions happen.
Temperature is probably the most obvious one. Higher temperatures mean faster reactions because particles have more energy to collide and react. You can spot this on graphs as steeper gradients show higher rates.
Concentration measures how many particles are dissolved in a given volume of solvent, whilst pressure does the same job for gases. More particles packed into the same space means more collisions and faster reactions.
Surface area matters loads when solids react with liquids or gases. Imagine trying to dissolve a whole sugar cube versus granulated sugar - the powder dissolves much faster because there's more surface exposed to react.
Quick Tip: Remember that catalysts are like helpful friends - they speed up reactions without getting used up themselves, making the whole process more efficient.
2
of 2
Testing Concentration Effects in the Lab
When you're investigating how concentration affects reaction rate, you'll need to design a proper experiment that only changes one thing at a time. The classic example uses sodium thiosulfate and hydrochloric acid - as they react, the solution becomes cloudy.
Your control variables (things you keep exactly the same) include using the same solutions, same mass of sodium thiosulfate, and same temperature. This ensures your results are fair and reliable.
The dependent variable (what you measure) is the time taken for a cross drawn on paper to disappear under the beaker. The independent variable (what you change) is the volume of hydrochloric acid you add.
Your method is straightforward: draw a cross on paper, put it under your beaker, add your chemicals, start timing, and stop when the cross vanishes. Always repeat your experiments to spot any dodgy results and make your conclusions more trustworthy.
Lab Success: Remember to wear safety goggles and work in a well-ventilated area - some reactions produce gases that aren't pleasant to breathe in!
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Chemistry310 views·Updated 17 Jul 2026·2 pagesUnderstanding Reaction Rates for AQA GCSE Chemistry
M
Mary!@mfr22
Chemical reactions don't all happen at the same speed - some are lightning fast whilst others take ages. Understanding what makes reactions go faster or slower is crucial for your chemistry studies and helps explain everything from cooking food to...
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of 2
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Five Key Factors That Control Reaction Speed
Think of reaction rate like the speed limit on a motorway - certain conditions can make reactions zoom along or crawl at a snail's pace. There are five main factors that control how quickly chemical reactions happen.
Temperature is probably the most obvious one. Higher temperatures mean faster reactions because particles have more energy to collide and react. You can spot this on graphs as steeper gradients show higher rates.
Concentration measures how many particles are dissolved in a given volume of solvent, whilst pressure does the same job for gases. More particles packed into the same space means more collisions and faster reactions.
Surface area matters loads when solids react with liquids or gases. Imagine trying to dissolve a whole sugar cube versus granulated sugar - the powder dissolves much faster because there's more surface exposed to react.
Quick Tip: Remember that catalysts are like helpful friends - they speed up reactions without getting used up themselves, making the whole process more efficient.
2
of 2Sign up to see the content. It's free!
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By signing up you accept Terms of Service and Privacy Policy
Testing Concentration Effects in the Lab
When you're investigating how concentration affects reaction rate, you'll need to design a proper experiment that only changes one thing at a time. The classic example uses sodium thiosulfate and hydrochloric acid - as they react, the solution becomes cloudy.
Your control variables (things you keep exactly the same) include using the same solutions, same mass of sodium thiosulfate, and same temperature. This ensures your results are fair and reliable.
The dependent variable (what you measure) is the time taken for a cross drawn on paper to disappear under the beaker. The independent variable (what you change) is the volume of hydrochloric acid you add.
Your method is straightforward: draw a cross on paper, put it under your beaker, add your chemicals, start timing, and stop when the cross vanishes. Always repeat your experiments to spot any dodgy results and make your conclusions more trustworthy.
Lab Success: Remember to wear safety goggles and work in a well-ventilated area - some reactions produce gases that aren't pleasant to breathe in!
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