Water Cycle Flashcards
A pot is boiling water. ‘White smoke’ is observed above the boiling water and ‘bubbles’ are observed in the water.
(a) What is the white smoke observed and explain why it occurs.
(b) What are the ‘bubbles’ observed in the pot of boiling water and explain why it occurs.
(a)The white smoke is small water droplets. The steam escaping from the boiling water loses heat to the cooler surrounding air and condensed to form water droplets.
(b) The bubbles are water in its gaseous state. The water near the bottom of the pot gains heat from the flame, changing it to steam. These ‘bubbles’ rise to the top and escape.
A pot filled with water was put on a hot plate and covered with a lid. After 5 min, it is observed that water droplets were formed on the underside of the lid.
Explain why.
The water in the pot gained heat from the hot plate to evaporate into the water vapor. When the hotter water droplets came into contact with the cooler lid, it lost heat to the lid and condensed into water droplets.
How is evaporation different from boiling.
Define the processes that ocur in the water cycle.
Evaporation takes place at the surface of the liquid while boiling takes place through out the liquid.
Evaporation takes place at any temperature while boiling takes place at a fixed temperature
A z x heat from the surroundings and changes to a z at a fixed temperature
z = liquid/solid/gas
x = loses/ gains
except for evaporation
Explain how spraying your face with fine mist on a a windy and warm day helps you cool down.
You will lose heat to the water droplets when the water droplets evaporate to form water vapor. The presence of wind and a higher surrounding temperature increase the rate of evaporation, making the you fell cooler.
Thames noticed when he got out of an air-conditioned bus in a hot afternoon, the glass lenses of his spectacles would ‘fog up’. Explain why this happens.
Water vapor is in the surrounding air. When the hotter water vapor comes into contact with the cooler glass surface, it condenses to become water droplets and make the glass lenses ‘fog up’.
3 containers, A, B and C, were filled with the same volume of water. A was the longest, followed by B, than C. All were placed in a field.
(a) What can be observed about the volume of water left in each container after 2 days?
(b) Explain why
Container A has the least amount of water left, followed by B, than C.
The water in A had the greatest exposed surface area. Thus, the water in A can gain heat from the surroundings to evaporate the fastest, followed by B than C
(a) 300ml of tap water was poured into two glasses. The glass in set-up A was covered with an airtight lid and both set-ups were left near the window. After a day, it was observed that water droplets were formed in Set up A but not in Set=up B. Explain why.
(b) A bottle garden is where some plants are pot in a glass bottle and sealed. Based on your previous answer, explain how the plants can grow without any water being added into the bottle.
(a) Water gained heat and evaporated in both set-ups A and B. The hotter water vapour in A lost heat to the cooler inner surface of the glass and condensed to form water droplets. Water vapour escapes from B.
(b) Water in the soil evaporates to form water vapour. Plants also take in water in the soil and lose water vapour through the stomata during respiration. Water vapour loses heat and condenses on the the cooler surfaces of the bottle and subsequently returns to the soil as it drips down
