P6 - Molecules and Matter Flashcards
Define density?
Its mass per unit volume
Which has a higher density - wood or concrete?
Concrete
What is the equation for density?
Density = mass / volume
What do you use to measure the mass of an object?
An electronic balance
What two ways can you measure the volume of an object?
Measure its dimensions and do length x width x height or lower it into a measuring cylinder partly filled with water and measure the rise in water level.
What is the density of water?
1000 kg/metres cubed
True or False - objects with a density lower than water will sink?
FALSE - objects with a density lower than water float in water
Which states of matter flow?
Liquid and Gas
Which states of matter are fixed shape?
Solid, the others fit into the shape of a container
Which states of matter have a fixed volume?
Solids and Liquids
Which states of matter have a high density?
Solids and liquids
How can states be changed?
By heating or cooling the substance
Does the mass of a substance change when it changes state?
NO - when the state changes, the number of particles in the substance stays the same so the mass is the same.
Which states have the most and least amount of energy for a fixed amount?
Gases have the most energy and solids have the least
Draw the arrangement of particles of a substance in solid, liquid and gas states
See page 73 of text book for answer
Describe the arrangement of particles in a solid?
Particles are held closely next to each other in fixed positions, they vibrate in these positions so solids keep their shape.
Describe the arrangement of particles in a liquid?
They are in contact with each other, they move at random meaning a liquid doesn’t have its own shape and can flow.
Describe the arrangement of particles in a gas?
They move about at random and much faster than in a liquid, they are much further apart than liquid hence their density if much less.
True or False - temperature of a substance stays the same when undergoing a change of state?
True
Define melting point?
The temperature at which a solid changes to a liquid
Define boiling point?
The temperature at which a liquid turns into a gas
Define freezing point?
The temperature at which a liquid changes to a solid
What happens to the melting point of water when impurities such as salt are added? How can this be beneficial?
The melting point of water is lowered when salt is added. This means salt can be added to grit to cover roads to ensure roads don’t get icy
What is the melting point of water?
0 degrees C
What is the boiling point of water?
100 degrees C
Can you understand melting and boiling points from a graph?
See page 75
Define latent heat?
The energy transferred to a substance when it changes its state
What does fusion mean?
It is used to describe melting because different solids can be joined together when melted
True or False - evaporation occurs at the surface of the liquid when the liquid below is a boiling point?
T
What temperature does evaporation occur at?
Any temperature
