Tricky topics in GCSE Science: Displacement Reactions
Through analysing the usage data of Tassomai students and identifying some common mistakes in their quizzes we can see which topics GCSE science students struggle with the most. In this series of blogs we’ll post a brief explainer on each of these tricky topics to help GCSE science students get up to speed and prepare for exams.
Displacement Reactions are an important topic for GCSE chemistry students to get to grips with, as it’s an exam specification point for major exam boards including:
✔ AQA
✔ EDEXCEL
✔ OCR 21ST CENTURY
✔ OCR GATEWAY
What are Displacement Reactions?
A displacement reaction is a type of chemical reaction where a more reactive element displaces (or pushes out) a less reactive element from a compound. These reactions typically occur between metals or between halogens.
How Displacement Reactions Work
Metals:
When a more reactive metal comes into contact with a compound containing a less reactive metal, the more reactive metal takes the place of the less reactive one.
For example, if you place a piece of magnesium (which is more reactive) into a solution of copper sulfate (which contains the less reactive copper), magnesium will displace copper from the compound, forming magnesium sulfate and leaving copper as a solid.
Here’s a Tassomai quiz question about Displacement Reactions:
This is one of several retrieval practice questions about Displacement Reactions that’s shown to Tassomai students. Retrieval practice is a proven learning method to embed knowledge through testing.
The question asks: A displacement reaction ---(1)--- take place between SODIUM FLUORIDE (NaF) and CHLORINE (Cl₂) because ---(2)---.
1. 1: will not ; 2: chlorine is MORE
reactive than fluorine
2. 1: will not; 2: chlorine is LESS
reactive than fluorine
3. 1: will; 2: chlorine is MORE reactive than fluorine, so SODIUM CHLORIDE + fluorine will be formed
4. 1: will; 2: chlorine is LESS reactive than fluorine, so SODIUM CHLORIDE + fluorine will be formed
To help us dive deeper into this topic we’ve enlisted the help of Mai, Tassomai’s built-in AI-powered tutor.
Tassomai users can ask Mai for help if they’re stuck on a quiz question or need some terminology explained to them.
If a student chooses the wrong answer, they can ask Mai to explain why it’s incorrect.
Let’s ask Mai to explain the answers to the quiz question!
Understanding the Displacement Reaction with Sodium Fluoride and Chlorine
In the world of chemistry, not all elements play nicely together! Let's dive into why the chosen answer was incorrect and uncover the right choice. 🧪
The Correct Answer Explained:
"will not": This part is correct because a displacement reaction does not occur.
"chlorine is LESS reactive than fluorine": This is the key! In the reactivity series, fluorine sits above chlorine, making it more reactive. Therefore, chlorine can't displace fluorine from sodium fluoride (NaF).
Why the Other Options Don't Fit:
"will not"; "chlorine is MORE reactive than fluorine": Correct start, but the reasoning was off. In reality, fluorine is the bully in the playground and won't let chlorine take its place in NaF.
"will; chlorine is MORE reactive than fluorine, so SODIUM CHLORIDE + fluorine will be formed": This suggests a displacement that isn't possible because chlorine isn't the tough guy here; fluorine is!
"will; chlorine is LESS reactive than fluorine, so SODIUM CHLORIDE + fluorine will be formed": Again, this outlines a reaction that can't happen in reality. Even though it correctly states chlorine is less reactive, the reaction implied is incorrect because no displacement would occur.
Fun Fact! 🌟
Did you know fluorine is so reactive it can even react with noble gases under certain conditions? Talk about being reactive!
Remember, in chemistry, it's not just about what happens, but why it happens. Keep questioning and exploring! 🕵️♀️🔬
Here’s how Mai’s explanation would look when shown to students using the Tassomai app.
As you can see, Mai sometimes throws in a fun fact to help students remember a topic.
Learn more about Displacement Reactions
We hope you found Mai’s explanation helpful. If you’d like to learn more about Displacement Reactions this GCSE Chemistry YouTube video presented by Murray, the founder of Tassomai.
To see more tricky GCSE topics explained, click here for the full list of Tricky Topics blogs.
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