Reversible changes booklet
Reversible changes booklet
- Unit 1: The human body
- Unit 2: Materials
- Unit 3: Rocks, the rock cycle and soil
- Unit 4: Food chains and food webs
- Unit 5: Forces and electricity
- Unit 6: Light and the Solar system
🌟 This Topic is About...
- 🔄 I will learn about changes to substances that can be reversed.
- 🧪 I will choose the right materials and equipment for experiments.
- ⚠️ I will learn how to stay safe and spot risks during practical work.
- 💧 I will use the particle model to explain how temperature affects dissolving.
- 🔍 I will make predictions and check if my results match them.
- 📊 I will record my observations and measurements in tables.
- ⚖️ I will decide if a test is fair and explain why.
- 💬 I will draw conclusions from my results and measurements.
- ❓ I will ask my own questions and plan how to investigate them.
Let’s explore science and become great investigators! 🔬💙
🌟 Key Words
- irreversible
- physical change
- rate
- reversible
- solute
- solvent
- uniform
📖 Tap to Learn the Meanings!
- 🔁 irreversible: A change that cannot be undone, like burning wood 🔥.
- ⚗️ physical change: When something changes form but not what it’s made of, like ice melting ❄️.
- ⏱️ rate: How fast or slow something happens.
- 🔄 reversible: A change that can be undone, like water freezing and melting again 💧.
- 🧂 solute: The solid that dissolves in a liquid, like sugar in water 🍬.
- 💧 solvent: The liquid that dissolves another substance, like water 🌊.
- ⚖️ uniform: When a mixture looks the same all the way through.
You’re mastering new science words! 🌟📘
💧 Changes to Substances
In a warm place, solid ice melts to become liquid water. This is a change of state. A change of state is a physical change. A physical change alters how a substance looks or feels, but the substance does not change into a new one.
❄️ Reversible Changes
When you put the water back in the freezer it becomes a solid again. We say that the change is reversible. This means we can change solid ice to liquid water and also change liquid water back to solid ice.
🔥 Heating and Cooling Water
Heating causes ice to melt into liquid water. When the water loses heat and cools, it becomes solid again. The diagram shows how ice and water change state between solid and liquid.
🧮 The Change of State Formula: $\text{Liquid water} \;\xleftrightarrow[\text{Cooling}]{\text{Heating}}\; \text{Solid ice}$
🔥 Irreversible Changes
What happens when we burn a match? Can the match change back to the way it was? Some changes to substances cannot be reversed. These are called irreversible changes. They turn one substance into another new substance. For example, burning a match changes the wood into a black material called carbon. This is a chemical change.
🤔 FUN QUESTIONS
1. When you mix boiling water with jelly powder it becomes a liquid. In the fridge it becomes solid. Can we make jelly change back to a liquid? Draw a simple flow diagram to explain your answer.
🌟 Show me!
2. Does boiling an egg cause a reversible or irreversible change? Explain why.
🌟 Show me!
🔍 Think like a Scientist 1: Demonstrate a Reversible Change
🤔 Task: Think of a reversible change to a substance and describe what happens.
- Think of a reversible change to a substance. Describe the change.
- a) Decide how you could demonstrate this reversible change.
b) How will you work safely? - Your teacher will put out some materials and equipment. Choose and collect what you will need.
- a) Demonstrate the reversible change you chose to another group. Ask them to describe what happens.
b) Explain how to change the substance back to the way it was before you changed it.
💭 How are we doing?
As a group, point to one of the faces to answer the questions. 😊 😐 😟
- Could we think of a reversible change to demonstrate?
- Could we choose and use suitable materials and equipment?
- Could we demonstrate that the change is reversible?
🌊 Dissolving
Some substances can dissolve in water or other liquids. For example, sea water is salty because salt is dissolved in the water. The substance that dissolves is called the solute, and the liquid it dissolves in is called the solvent. Together, the solute and solvent form a solution.
🧂 How Dissolving Works
When a solute dissolves, its tiny particles move between the particles of the solvent. The solute spreads out evenly so that you can no longer see it. This makes the solution look the same all the way through — we call this a uniform mixture.
☕ Can We Make Solids Dissolve Faster?
The coffee and sugar form a solution. The sugar will dissolve faster if Marcus stirs the solution. Stirring is one way to make solid solutes dissolve faster. Stirring helps the solute particles spread into the spaces between solvent particles more quickly. This increases the rate of dissolving — the rate means how fast something happens.
🔥 Temperature and Dissolving
There are other factors that make solids dissolve faster. Have you ever tried to make coffee with cold water from the fridge? Hot water helps substances dissolve more quickly. This is why we use hot water when making coffee or tea — heat speeds up the dissolving process.
🔍 Think like a Scientist 2: Does Water Temperature Affect the Rate of Dissolving?
🤔 Question: Does sugar dissolve more quickly in hot or cold water?
🧰 You will need: sugar, glass jars, cold water, hot water, teaspoon, measuring cylinder, stopwatch or timer ⏱️
🛡️ Safety First:
- Don’t touch the hot water. 🔥
- Be careful not to knock over the jar of hot water. ⚠️
📝 Method:
- Make a prediction: Will sugar dissolve faster in hot or cold water? Say why you think this. 💭
- Stir a teaspoon of sugar into 100 ml of cold water in a glass jar. ❄️
- Stir a teaspoon of sugar into 100 ml of hot water in a glass jar. 🔥
- Time how long it takes for the sugar to dissolve in both jars. ⏱️
- Record your results in a table. 📋
- a) In which jar did the sugar dissolve quickest? Suggest a reason.
b) Was your prediction correct? - How did you make sure your test was fair? ⚖️
- Write down what you conclude about the effect of temperature on dissolving a solute. 🧂💧
🌟 Tap to See Answers
- 1: Sugar dissolves faster in hot water because heat makes particles move more quickly. 🔥💧
- 2: My prediction was correct! ✅
- 3: I used the same amount of water and sugar to keep the test fair. ⚖️
- 4: Higher temperature increases the rate of dissolving. 🌡️
Excellent scientific thinking! 👏🔬
🔥 How Heat Affects Particle Movement
The particles in matter are always moving. When we increase the temperature of a substance, heat adds energy to its particles. This extra energy makes the particles move faster and spread out more.
🌊 Heating and Dissolving
In a heated solvent, the solute particles also gain energy and move faster than in a cooler solvent. This allows the solute particles to spread more easily through the solvent, making the solute dissolve faster.
🤔 FUN QUESTIONS
1. What does the rate of dissolving mean?
🌟 Show me!
2. Name two factors that affect the rate of dissolving.
🌟 Show me!
3a. How does heating affect the particles in a solution?
🌟 Show me!
3b. Explain how this affects dissolving.
🌟 Show me!
4. Explain why sugar will dissolve on its own in a cup of cold water if we leave it long enough.
🌟 Show me!
🔍 Think like a Scientist 3: Ask and Investigate a Question About Dissolving
🤔 Task: Work with a partner to plan and carry out your own investigation about dissolving.
📝 Steps:
- With your partner, think of a question about dissolving that you would like to find the answer to. 💭
- Decide on the type of scientific enquiry you will use to answer your question — for example, a fair test, doing research, or observing over time. 🔬
- Find out the answer to your question by carrying out your investigation. 🧪
- Make a short presentation to share your findings with the class. 🎤
🌟 Tips for Success
- Ask clear questions that can be tested. ❓
- Make sure your test is fair and safe. ⚖️🛡️
- Work carefully and record what you find. ✍️
- Share your results confidently and clearly! 🌈
Well done — you’re thinking like a real scientist! 👏🔬