Edexcel IGCSE Chemistry States of Matter PDF

Head to www.savemyexams.com for more awesome resources Edexcel IGCSE Chemistry Your notes States of Matter Contents The Three States of Matter Diffusion & Dilution Solutions Solubility Practical: Investigat...

Head to www.savemyexams.com for more awesome resources Edexcel IGCSE Chemistry Your notes States of Matter Contents The Three States of Matter Diffusion & Dilution Solutions Solubility Practical: Investigate the Solubility of a Solid in Water at a Specific Temperature Page 1 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The Three States of Matter Your notes States of matter The three states of matter are solids, liquids and gases A substance can usually exist in all three states, dependent on temperature (and pressure) State changes occur at the melting point (solid to liquid, liquid to solid) and at the boiling point (liquid to gas and gas to liquid) Melting and freezing occur at the melting point Boiling and condensing take place at the boiling point Individual atoms themselves do not share the same properties as bulk matter The three states of matter can be represented by a simple model In this model, the particles are represented by small solid spheres Summary of the properties of the three states of matter Solid Liquid Gas Diagram Arrangement of Regular arrangement Randomly Randomly arranged particles arranged Movement of Vibrate about a fixed position Move around each Move quickly in all particles other directions Closeness of Very close Close Far apart particles Page 2 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Changing states of matter The amount of energy needed to change state from solid to liquid and from liquid to gas depends on Your notes the strength of the forces between the particles The stronger the forces between the particles, the more energy that is needed to overcome them Therefore, the stronger the forces between the particles the higher the melting point and boiling point of the substance Changing states is a physical change The particles themselves remain the same, it is just the forces between the particles which change Melting Melting is when a solid changes into a liquid Heat / thermal energy absorbed by the particles is transformed into kinetic energy This causes the particles to vibrate more and start to move / flow Melting happens at a specific temperature, known as the melting point (m.p.) Boiling Boiling and evaporation are both when a liquid changes into a gas However, there is a key difference between boiling and evaporation In boiling, heat / thermal energy causes bubbles of gas to form inside the liquid, allowing for liquid particles to escape from the surface and within the liquid Boiling happens at a specific temperature, known as the boiling point (b.p.) Freezing Freezing is when a liquid changes into a solid This is the reverse of melting and occurs at the same temperature as melting So, the melting point and freezing point of a pure substance are the same For example, water freezes and melts at 0 ºC Freezing needs a significant decrease in temperature (or loss of thermal energy) and occurs at a specific temperature Evaporation Page 3 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Evaporation occurs over a range of temperatures It can happen at temperatures below the boiling point of the liquid Your notes Evaporation occurs only at the surface of liquids where high energy particles can escape from the liquid's surface at low temperatures The larger the surface area and the warmer the liquid surface, the more quickly a liquid can evaporate Condensation Condensation occurs when a gas changes into a liquid on cooling and takes place over a range of temperatures When a gas is cooled its particles lose energy and when they bump into each other they lack the energy to bounce away again, instead, they group together to form a liquid Sublimation When a solid changes directly into a gas This happens to only a few solids, such as iodine or solid carbon dioxide The reverse reaction also happens and is called desublimation or deposition Changing states of matter Page 4 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes State changes require a change in the energy of the particles Examiner Tips and Tricks Questions may show state changes with a reversible arrow: ⇌, which means that the process can go forwards and backwards. Page 5 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Diffusion & Dilution Your notes Diffusion and dilution Diffusion and dilution experiments support a theory that all matter (solids, liquids and gases) is made up of tiny, moving particles Diffusion in gases Diffusion of red-brown bromine gas Description: Here, we see the diffusion of bromine gas from one gas jar to another After 5 minutes the bromine gas has diffused from the bottom jar to the top jar Explanation: The air and bromine particles are moving randomly and there are large gaps between particles The particles can therefore easily mix together Diffusion in liquids Page 6 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Page 7 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Diffusion of potassium manganate(VII) in water over time Description: When potassium manganate (VII) crystals are dissolved in water, a purple solution is formed A small number of crystals produce a highly intense colour Explanation: The water and potassium manganate (VII) particles are moving randomly and the particles can slide over each other The particles can therefore easily mix together Diffusion in liquids is slower than in gases because the particles in a liquid are closely packed together and move more slowly Dilution Page 8 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Dissolving potassium manganate (VII) in water Description: When potassium magnate (VII) crystals are dissolved in water, the solution can be diluted several times The colour fades but does not disappear until a lot of dilutions have been done Explanation: This indicates that there are a lot of particles in a small amount of potassium manganate (VII) and therefore the particles must be very small Examiner Tips and Tricks Diffusion and dilution provide evidence for the kinetic theory of matter. Page 9 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Solutions Your notes Solutions terminology You need to know all the following terms used when describing solutions: Term Meaning Example Solvent The liquid in which a solute dissolves The water in sea water Solute The substance which dissolves in a liquid to form a solution The salt in sea water Solution The mixture formed when a solute is dissolved in a solvent Sea water Saturated A solution with the maximum concentration of solute Sea water in the Dead solution dissolved in the solvent Sea Soluble Describes a substance that will dissolve Salt is soluble in water Insoluble Describes a substance that will not dissolve Sand is insoluble in water Page 10 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Solubility Your notes Solubility Solubility is a measurement of how much of a substance will dissolve in a given volume of a liquid The liquid is called the solvent The solubility of a gas depends on pressure and temperature Different substances have different solubilities Solubility can be expressed in g per 100 g of solvent Solubility of solids is affected by temperature As temperature increases, solids usually become more soluble Solubility of gases is affected by temperature and pressure; in general: As pressure increases, gases become more soluble As temperature increases, gases become less soluble Solubility curves Solubility graphs or curves represent solubility in g per 100 g of water plotted against temperature To plot a solubility curve, the maximum mass of solute that can be dissolved in 100 g of water before a saturated solution is formed, is determined at a series of different temperatures Solubility curve for three salts Page 11 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes While the solubility of most salts increases with temperature, sodium chloride, or common salt, hardly changes at all Worked Example Use the solubility curve to answer these questions: 1. Determine how much potassium nitrate will dissolve in 20 g of water at 50 °C? 2. 200 cm3 of saturated lead(II) nitrate solution was prepared at a temperature of 90 °C. What mass of lead(II) nitrate crystals form if the solution was cooled to 40 °C? Answers: 1. At 50 °C, the solubility of potassium nitrate is 68 g per 100 g of water So scaling, 68 x (20 / 100) = 13.6 g of potassium nitrate will dissolve in 20 g of water 2. Solubility of lead(II) nitrate at 90 oC is 118 g / 100 g water, and 64 g / 100 g water at 40 °C. Therefore for mass of crystals formed = 118 – 64 = 54 g (for 100 cm3 of solution). However, 200 cm3 of solution was prepared, So total mass of lead(II) nitrate crystallised = 2 x 54 = 108 g Page 12 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Examiner Tips and Tricks As temperature increases, solids usually become more soluble and gases become less soluble. Page 13 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Practical: Investigate the Solubility of a Solid in Water at a Specific Temperature Your notes Practical: Investigate the solubility of a solid in water at a specific temperature Aim To measure the solubility of a salt at different temperatures Method 1. Prepare two beakers, one as a hot water bath and one as an ice bath 2. Using a small measuring cylinder, measure out 4 cm3 of distilled water into a boiling tube. 3. On a balance weigh out 2.6 g of ammonium chloride and add it to the boiling tube 4. Place the boiling tube into the hot water bath and stir until the solid dissolves 5. Transfer the boiling tube to the ice bath and allow it to cool while stirring 6. Note the temperature at which crystals first appear and record it in a table of results 7. Add 1 cm3 of distilled water then warm the solution again to dissolve the crystals 8. Repeat the cooling process again noting the temperature at which crystals first appear 9. Continue the steps until a total of 10 cm3 of water has been added Page 14 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Apparatus for investigating the solubility of a salt with temperature Results The results for method 2 can be recorded in a table The solubility in g / 100g is calculated by dividing the mass of the solute by the volume and multiplying by 100 Example results table Volume of water in boiling tube / Solubility in g per 100 Temperature at which crystals appear / cm3 g oC 4 65 5 52 6 43 Page 15 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources 7 37 Your notes 8 32 9 29 10 26 Graph The results can be used to plot a solubility curve for ammonium chloride at different temperatures Solubility is on the y-axis and temperature is on the x-axis Conclusion The shape of the graph will allow us to state how the solubility varies with temperature Page 16 of 16 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers