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Changes of State

Changes of State. Heat will change a material from a solid to a liquid to a gas . . A liquid evaporates into a gas when it is warmed. It does NOT disappear. A solid melts into a liquid when it is warmed. .

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Changes of State

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  1. Changes of State

  2. Heat will change a material from a solid to a liquid to a gas. • A liquid evaporates into a gas when it is warmed. It does NOT disappear. • A solid melts into a liquid when it is warmed.

  3. Removing heat (cooling) will change a material from a gas to a liquid to a solid. • A gas condenses into a liquid when it is cooled. • A liquid freezes into a solid when it is cooled • Dew is formed when water vapour in the air condenses. On a cold night dew can freeze to form frost.

  4. Changing states Changing the temperature of a substance can result in a change in its state. Below is a diagram showing you how these states are linked together. Melting is when a solid turns into a liquid at its melting point and freezing is the opposite of melting. Boiling is when a liquid is bubbling, the liquid is turning into a gas inside the liquid, at its boiling point. Condensing is a gas turning into a liquid.

  5. of a substance is that temperature when both the solid and the liquid state can exist together. It is the temperature when the solid turns into a liquid or vice versa. The melting point of a substance is that temperature when the gas state of the substance forms bubbles in its liquid. It is boiling! It is the temperature when the liquid turns into a gas. The boiling point is when the solid state of the substance changes into the gas state without going through the liquid state and vice versa. Sublimation

  6. Symbol or Formula Symbol or Formula Symbol or Formula Name Name Name Melting point°C Melting point°C Melting point°C Boiling point°C Boiling point°C Boiling point°C Densityg/cm3 Densityg/cm3 Densityg/cm3 Helium Helium Helium He He He -270 -270 -270 -269 -269 -269 0.00017 0.00017 0.00017 Carbon (diamond) Carbon (diamond) Carbon (diamond) C C C 3550 3550 3550 4830 4830 4830 3.5 3.5 3.5 Nitrogen Nitrogen Nitrogen N2 N2 N2 -210 -210 -210 -196 -196 -196 0.0012 0.0012 0.0012 Oxygen Oxygen Oxygen O2 O2 O2 -219 -219 -219 -183 -183 -183 0.0013 0.0013 0.0013 Sodium Sodium Sodium Na Na Na 98 98 98 890 890 890 0.97 0.97 0.97 Argon Argon Argon Ar Ar Ar -189 -189 -189 -186 -186 -186 0.0017 0.0017 0.0017 Iron Iron Iron Fe Fe Fe 1539 1539 1539 2887 2887 2887 7.9 7.9 7.9 Bromine Bromine Bromine Br Br Br -7 -7 -7 58 58 58 3.1 3.1 3.1 Tungsten Tungsten Tungsten W W W 3377 3377 3377 5527 5527 5527 19.3 19.3 19.3 Mercury Mercury Mercury Hg Hg Hg -39 -39 -39 357 357 357 13.5 13.5 13.5 Radon Radon Radon Rn Rn Rn -71 -71 -71 -62 -62 -62 0.0089 0.0089 0.0089 Sodium Chloride Sodium Chloride Sodium Chloride NaCl NaCl NaCl 808 808 808 1465 1465 1465 2.2 2.2 2.2 Sulphur dioxide Sulphur dioxide Sulphur dioxide SO2 SO2 SO2 -75 -75 -75 -10 -10 -10 0.0027 0.0027 0.0027 Calcium Chloride Calcium Chloride Calcium Chloride CaCl CaCl CaCl 782 782 782 1600 1600 1600 2.5 2.5 2.5 Carbon dioxide Carbon dioxide Carbon dioxide CO2 CO2 CO2 -56 -56 -56 -78 -78 -78 0.0018 0.0018 0.0018 Ethanol Ethanol Ethanol C2H6O C2H6O C2H6O -114 -114 -114 78 78 78 0.8 0.8 0.8 Water Water Water H2O H2O H2O 0 0 0 100 100 100 1.0 1.0 1.0 Iron oxide Iron oxide Iron oxide Fe2O3 Fe2O3 Fe2O3 1457 1457 1457 1562 1562 1562 5.2 5.2 5.2 Magnesium oxide Magnesium oxide Magnesium oxide MgO MgO MgO 2900 2900 2900 3600 3600 3600 3.6 3.6 3.6 Melting point, boiling point, and density Different substances have different melting points, boiling points and densities. The table shows the melting points, boiling points and densities of a number of substances.

  7. State of a substance at room temperature Here is a method for working out if a substance is a solid, liquid or gas at room temperature. This question is often asked in your tests. • Look up the substance's melting and boiling points • 2. Draw a number line 3. Put the melting, boiling point and room temperature (this is always 20°C) on the number line. • 4. Label it solid below melting point, liquid between the melting and boiling points and gas above the boiling point. • 5. The state of the substance at room temperature is shown when looking at 20°C, room temperature.

  8. Bromine Melting point Room temperature Boiling point Bromine is a liquid at room temperature. Nitrogen Melting point Boiling point Room temperature Nitrogen is a gas at room temperature. • Do the same with the others!

  9. What happens during state change? When a substance melts it changes from a solid to a liquid. During this change the temperature remains constant. The energy supplied causes the bonds between the particles in the solid to break. Similarly, when a liquid is boiling its temperature does not rise. The energy goes to overcome the forces between the particles in the liquid turning the liquid into a gas. A heating curve shows this in more detail.

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