States of matter Banker

1. (a) Which statement describes the particles in a liquid?A close together, in a regular arrangement, vibrating about fixed positionsB close together, in an irregular arrangement, moving past one anotherC far apart, in an irregular arrangement, moving quickly in all directionsD far apart, in a regular arrangement, moving slowly [1]

1. (a) The melting points and boiling points of four substances are shown.Substance P: melting point −95 °C, boiling point 69 °CSubstance Q: melting point −182 °C, boiling point −162 °CSubstance R: melting point 44 °C, boiling point 280 °CSubstance S: melting point 0 °C, boiling point 100 °CWhich substance is a gas at 0 °C?A PB QC RD S [1]

1. (a) Describe the arrangement and the movement of the particles in a solid. [2]
2. (b) Describe how the arrangement and movement of the particles change when the solid melts. [2]
3. (c) State two differences between the particles in a liquid and the particles in a gas. [2]

The table shows melting points and boiling points.Substance A: melting point −218 °C, boiling point −183 °CSubstance B: melting point 801 °C, boiling point 1413 °CSubstance C: melting point −39 °C, boiling point 357 °CSubstance D: melting point 17 °C, boiling point 118 °C

1. (a) State the physical state of each substance at 25 °C. [2]
2. (b) Which substance is a liquid over the widest range of temperature? Show your working. [2]
3. (c) On a cold night the temperature falls to 10 °C. Which substance changes state? Name the change. [2]

1. (a) Name the change of state in each case.(i) Ice cubes in a glass of lassi turn to water.(ii) Drops of water form on the outside of a cold bottle of water.(iii) Hot candle wax drips onto a table and goes hard.(iv) A puddle of rainwater disappears on a sunny afternoon. [4]
2. (b) In which of the changes in (a) is energy given out to the surroundings? [2]

Crushed ice at −12 °C was heated gently in a beaker and stirred. The temperature was recorded every 2 minutes.Time/min: 0, 2, 4, 6, 8, 10Temperature/°C: −12, 0, 0, 0, 15, 30

1. (a) Between which times was the ice melting? [1]
2. (b) Calculate the average rate of temperature rise, in °C per minute, between 6 and 10 minutes. [2]
3. (c) Suggest why the ice was crushed into small pieces. [1]
4. (d) Suggest why the mixture was stirred throughout. [1]

Substance Y is a pure compound. A sample of liquid Y is left to cool.

1. (a) Describe what happens to the movement of the particles as liquid Y cools and freezes. [2]
2. (b) Y starts to freeze at 54 °C. State its melting point. [1]

1. (a) A sealed steel cylinder of oxygen is left in hot sunshine. The volume of the cylinder does not change. Why does the pressure of the gas increase?A The gas particles become larger.B The number of gas particles increases.C The gas particles move faster and hit the walls more often and with more force.D The forces of attraction between the gas particles become stronger. [1]

1. (a) A gas is trapped in a syringe whose plunger moves freely, so the pressure stays constant. The syringe is placed in a freezer. What happens?A The volume decreases because the particles move more slowly.B The volume decreases because the particles shrink.C The volume increases because the particles move more slowly.D The volume stays the same because the pressure is constant. [1]

A solid X was heated at a steady rate and its temperature was recorded.Time/min: 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28Temperature/°C: −10, 3, 16, 16, 16, 28, 40, 52, 64, 74, 78, 78, 78, 78, 92

1. (a) State the melting point and the boiling point of X. [2]
2. (b) State the physical state of X at 5 minutes and at 16 minutes. [2]
3. (c) Explain, in terms of particles, why the temperature stays constant between 20 and 26 minutes even though heating continues. [2]

A family in Lahore hangs wet washing on a roof-top line.

1. (a) Name the change of state when washing dries. [1]
2. (b) Explain, in terms of particles, why the washing dries faster on a hot day than on a cool day. [2]
3. (c) Explain why the washing dries faster when it is spread out on the line than when it is left folded in a basket. [2]

1. (a) Bromine boils at 59 °C and freezes at −7 °C. State the physical state of bromine at 25 °C and give a reason. [2]
2. (b) Name the change of state that happens when bromine vapour is cooled from 80 °C to 20 °C. [1]
3. (c) Is the change in (b) exothermic or endothermic? Explain your answer in terms of the forces between particles. [2]

A student melted a solid in a boiling tube in a hot water bath, then removed the tube and let it cool in air. She recorded the temperature every 30 seconds.Time/min: 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5Temperature/°C: 80, 71, 64, 58, 58, 58, 58, 58, 58, 58, 52, 47

1. (a) State the freezing point of the substance. [1]
2. (b) Calculate the average rate of temperature fall, in °C per minute, during the first 1.5 minutes. [2]
3. (c) Explain why the temperature stays constant between 2.0 and 4.5 minutes. [2]
4. (d) Suggest why the student stirred the liquid with the thermometer until it became too solid to stir. [1]

A party balloon filled with air at room temperature is put into a freezer at −18 °C for one hour.

1. (a) Describe what happens to the size of the balloon in the freezer. [1]
2. (b) Explain your answer to (a) in terms of the particles of air in the balloon. [3]
3. (c) State what happens to the balloon when it is taken out and warmed to room temperature again. [1]

1. (a) State whether each change is exothermic or endothermic: melting, boiling, condensing, freezing. [2]
2. (b) Explain why boiling is endothermic. [2]
3. (c) The boiling point of ethanol is 78 °C and that of water is 100 °C. What does this suggest about the forces between the particles in ethanol compared with water? [1]

Two identical shallow dishes each contained 60.0 g of propanone. One dish was kept at 20 °C and the other at 40 °C. The mass of each dish's contents was measured after 10 minutes.At 20 °C: final mass 57.6 gAt 40 °C: final mass 53.2 g

1. (a) Calculate the mass of liquid lost from each dish after 10 minutes. [2]
2. (b) Calculate the average rate of evaporation, in g per minute, at 40 °C. [1]
3. (c) Explain, using the kinetic particle theory, why evaporation is faster at 40 °C. [2]
4. (d) State two variables that must be kept the same for a fair comparison. [2]

1. (a) A solid is heated at a steady rate. Its temperature stays constant at 63 °C for four minutes while it melts. What happens to the energy supplied during these four minutes?A It increases the kinetic energy of the particles, so they move faster.B It is used to overcome the forces of attraction between the particles.C It is lost to the surroundings, so none reaches the solid.D It is used to break covalent bonds inside the particles. [1]

A driver measures the pressure in her car tyres before and after a long motorway journey from Islamabad to Lahore on a hot day. The pressure was 220 kPa before the journey and 245 kPa at the end.

1. (a) Explain, in terms of particles, why the pressure in the tyres is higher at the end of the journey. [3]
2. (b) Air can be squeezed into a tyre, but water cannot be compressed in the same way. Explain why. [2]

A student compared two samples, A and B, of the same white solid. Each sample was placed in a narrow tube held next to a thermometer in a beaker of water, which was heated slowly and stirred.Sample A: started to melt at 71 °C, completely melted at 71 °C.Sample B: started to melt at 62 °C, completely melted at 68 °C.

1. (a) Suggest why the tubes were heated in a beaker of water rather than directly in a Bunsen flame. [2]
2. (b) Calculate the range of temperature over which sample B melts. [1]
3. (c) Which sample is pure? Explain your answer using the results. [2]
4. (d) Suggest one way of making the temperature readings more reliable. [1]

A fixed mass of gas was kept at constant temperature in a sealed syringe. The pressure on it was changed and the volume measured.Pressure/kPa: 100, 200, 300, 400Volume/cm³: 240, 120, 80, 60

1. (a) Describe the pattern in the results. [1]
2. (b) Use the pattern to predict the volume of the gas at 150 kPa. [1]
3. (c) Explain, in terms of particles, why the volume decreases when the pressure is increased at constant temperature. [2]
4. (d) Predict how the volume at 200 kPa would change if the experiment were repeated at a higher temperature. Explain your answer. [2]

In many Pakistani homes drinking water is kept in an unglazed clay pot (matka). Water slowly seeps through the clay and evaporates from the outer surface.

1. (a) Explain, in terms of the energy of the particles, why water kept in the pot becomes cooler than the surrounding air. [3]
2. (b) Suggest why the pot cools the water better on a dry, windy day than on a humid, still day. [2]

1.0 g of liquid water at 100 °C has a volume of about 1.0 cm³. When it boils, 1.0 g of steam at 100 °C and atmospheric pressure has a volume of about 1700 cm³.

1. (a) Calculate how many times larger the volume of the steam is than the volume of the liquid water. [1]
2. (b) Use the kinetic particle theory to explain this large difference. [2]
3. (c) Suggest why a burn from steam at 100 °C is usually more severe than a burn from the same mass of water at 100 °C. [2]

1. (a) Four gases are released at the same moment at the front of a room at the same temperature. Which gas diffuses fastest?A carbon dioxide, CO₂B chlorine, Cl₂C methane, CH₄D nitrogen, N₂ [1]

A student drops one crystal of potassium manganate(VII) (purple) into a beaker of still water and leaves it for an hour.

1. (a) Describe what the student sees after one hour. [1]
2. (b) Name the process that causes this. [1]
3. (c) Explain, in terms of particles, why this happens even though the water is not stirred. [2]

A bottle of attar (a perfume oil) is opened at the front of a large hall.

1. (a) Explain why people at the back of the hall can smell the attar a few minutes later, even with no breeze. [2]
2. (b) Suggest how the time taken would change on a much colder day. Explain your answer. [2]

1. (a) A long glass tube has cotton wool soaked in concentrated ammonia at one end and cotton wool soaked in concentrated hydrochloric acid at the other. A white solid forms inside the tube. Where does it form, and why?A nearer the ammonia end, because ammonia molecules are heavierB nearer the hydrochloric acid end, because ammonia molecules have a lower mass and diffuse fasterC exactly in the middle, because both gases diffuse at the same rateD nearer the hydrochloric acid end, because hydrogen chloride molecules diffuse faster [1]

A glass tube 100 cm long was clamped horizontally. Cotton wool soaked in concentrated ammonia solution was pushed into one end and cotton wool soaked in concentrated hydrochloric acid into the other end at the same time. Both ends were sealed with bungs. After 4 minutes a white ring of solid appeared 59 cm from the ammonia end.

1. (a) Name the white solid and write a balanced equation for its formation. [2]
2. (b) Calculate the distance of the white solid from the hydrochloric acid end. [1]
3. (c) Explain why the white solid forms closer to the hydrochloric acid end. [2]
4. (d) State one safety precaution for this experiment and give a reason. [1]
5. (e) Suggest why both pieces of cotton wool must be put into the tube at the same time. [1]

The experiment with ammonia at one end of a long tube is repeated with hydrogen bromide gas, HBr, at the other end instead of hydrogen chloride. [Ar: H = 1, N = 14, Br = 80]

1. (a) Calculate the relative molecular mass of hydrogen bromide, HBr. [1]
2. (b) Name the white solid formed and predict whether it forms nearer the ammonia end or the hydrogen bromide end. Explain your prediction. [3]
3. (c) The experiment with hydrogen chloride (Mr 36.5) gave a ring 59 cm from the ammonia end in a 100 cm tube. Would the ring with hydrogen bromide be more or less than 59 cm from the ammonia end? Explain. [2]

Four identical Petri dishes of jelly (agar) were kept in water baths at different temperatures. A drop of coloured dye was placed in a small hole in the centre of each. The time taken for the colour to reach a circle 15 mm from the hole was recorded.Temperature/°C: 20, 30, 40, 50Time/min: 84, 61, 49, 35

1. (a) Calculate the rate of diffusion, in mm per minute, at 20 °C and at 50 °C. Give your answers to 2 significant figures. [2]
2. (b) Describe the relationship between temperature and rate of diffusion shown by the results. [1]
3. (c) Explain this relationship in terms of particles. [2]
4. (d) Suggest one source of error in this experiment and one way of improving the experiment to reduce it. [2]

A gas jar of air is placed upside down on a gas jar containing a few drops of liquid bromine. The brown vapour takes about 20 minutes to spread evenly through both jars. When the experiment is repeated with the air removed from the jars first, the brown colour fills both jars in less than a second.

1. (a) Explain why diffusion is much faster in gases than in liquids at the same temperature. [2]
2. (b) Explain why the brown colour fills the lower jar almost at once when the air has been pumped out first. [2]