Phases Of Water Flashcards
What are the 3 phases of water?
Liquid - water
Solid - ice
Gas- water vapour
In science these are called ‘states of matter’
What distinguishes gas from a liquid?
Gaseous water does not have a fixed volume - it fills any space into which it is put
Is a solid water shape fixed or unfixed?
It is fixed
Is solid water volume fixed or unfixed?
Fixed
Does liquid water have a fixed or unfixed shape?
Fixed
Does liquid water have fixed or unfixed volume?
Fixed
Does gas (water vapour) have fixed or unfixed shape?
Not fixed
Does gas (water vapour) have fixed or unfixed volume?
Not fixed
Does the volume of liquid change when it is melted from ice (solid) to water (liquid)?
No the volume is the same
What are the two gaseous forms of water?
Steam - invisible
Water vapour- cloud like
What is ‘steam’?
Scientists use the word steams to describe the invisible gaseous form of water that emerges from the spout when water boils
What is the difference between steam and water vapour?
The only difference between steam and water vapour is the temperature at which both gaseous forms exist
Steam is invisible
Water vapour you can see
What happens when steam cools as it meets the air?
It condenses in to tiny droplets of liquid water - rather like hot mist or a cloud
What temperature is steam produced at?
Above the boiling point
What temperature is water vapour produced at?
Air temperature
What term is given to refer to the changes from a liquid to a gas?
Evaporation
It can also be called vaporisation
What can evaporation also be known as ?
Vaporisation
What is the term given for the conversion of a gas to a liquid?
Condensation
Can cold air hold as much water vapour as warm air?
No
Why can cold air not hold as much water vapour?
The air is cold so cannot contain water vapour - this gets rejected as a liquid on a cold surface
How does condensation occur on windows when the temperature is low outside?
Because the air is too cold to hold the water vapour so it settles on a cold surface
What examples are consequence of water vapour present in the air?
Mist Fog Clouds Rain Condensation
What is the name of the process of the phase transition by which a solid is converted into a gas?
Sublimation
What is the name of the process of the phase transition by which a gas is converted into a solid?
Deposition
What is the name of the process of the phase transition by which a liquid is converted in to a gas?
Evaporation
What is the name of the process of the phase transition by which a gas is converted in to a liquid?
Condensation
What is the name of the process of the phase transition by which a solid is converted in to a liquid?
Melting
What is the name of the process of the phase transition by which a liquid is converted to a solid?
Freezing
How are molecules of water in ice arranged?
They are packed together in a uniform highly ordered - three dimensional arrangement
Each oxygen atom is surrounded by 4 other oxygen atoms
How are water molecules in ice bonded?
Covalently bonded
What do the hydrogen atoms in ice water lye between?
It lies in between each pair of oxygen atoms
What shape channels are water molecules in ice characterised by?
Large hexagonal open channels
Does ice take up more space than the liquid water it originated from?
Yes it does
Can water molecules in ice move around?
They can vibrate but they do not mov away from their fixed positions
What happens to the molecules of water when ice melts?
In ice the molecules of water are packed together in an ordered open structure. This degree of order is not maintained in a liquid. As ice melts, some of the hydrogen bonds between the water molecules are disrupted. In liquid water, the hydrogen bonds are constantly breaking and reforming between different molecules. This means that water molecules in liquid water can come closer together than water molecules in ice structure
Explain the movement of molecules in water?
They are fairly close together with attractions between them, they are able to move around in all directions. Movement of water molecules is nevertheless limited and liquid water retains some order in structure
Do water molecules in gaseous vapour attracted to each other?
No they have little attraction
Explain the movement of water molecules in gaseous vapour?
They are free to move in all directions
Collide with each other
Widely spaced out
Will same number of water molecules apply if gaseous vapour is compressed in to a smaller space?
Yea the same number of molecules will occupy a smaller volume
How are water molecules distributed when they are in the gaseous vapour phase?
The molecules will fill all the available space giving a random distribution of molecules
Where would your weight be less: on the Moon of the Earth?
Your weight would decrease if you went on the Moon where gravity is weaker than it is on the Earth. The moon is much lighter than the Earth and the downward pull on your body would be less on the Moon
What is a variable?
It is anything used in an experiment that can take on different values or characteristics. They are the raw materials of experiments in science because the relationship between them has the potential to tell us a lot
What is an independent variable?
Something that has been selected for investigation
E.g. Water
When written on a table should always be written on the left
What is a dependent variable?
What we use to measure the effects of changing the independent variable
E.g. Mass/height/
What is the controlled variable?
It is the measurement / characteristic that the scientist wants to keep constant
E.g. The amount of water molecules when investigating whether the mass and volume of water changes during a transition
What determines the phase of water?
Temperature
Pressure
A change in temperature and or pressure may cause water to change from one phase to another
This is true for other substances
What is the freezing temperature of water ?
0 degrees Celsius
What is the boiling temperature of water?
100 degrees Celsius
What is the boiling temperature for water on Mount Everest?
71 degrees Celsius
Define the term atmospheric pressure ?
The weight of air above you
What happens to gas molecules in higher altitude?
They decrease
How do molecules in the atmosphere produce pressure?
The molecules collide with each other and with surfaces they encounter. The collisions of the molecules with a surface exert a pressure on the surface ; the gas is pushing against the surface
What is the Sl unit of pressure?
Pascals (Pa)
What is the abbreviation of atmospheric pressure?
atm
What is the pressure of the atmosphere at sea level and is also known as normal atmospheric pressure?
1 atmosphere (atm)
How many pascals (Pa) is there in 1 atmosphere (atm)?
101 325 Pa
What is the pascal (Pa) unit a combination of?
A combination of the base units kilograms, metres and seconds
Why does pressure decrease in higher altitudes?
Because at higher altitudes there are fewer molecules of air in a given volume, so fewer collisions and thus lower pressure
On a graph which line is the x axis ?
Horizontal
On a graph which line is the y axis?
Vertical
What is the triple point in regard to phase of water?
It is where the pressure and temperature meet at a point that liquid water, ice and water vapour exist simultaneously
What are the conditions for the triple point?
Just above 0 degrees Celsius
And very low pressure
