Topic 2 - States of Matter and Mixtures Flashcards
Name the 3 states of matter and the chemical changed between them
Solid, Liquid and Gas Solid -> liquid = melting Liquid -> Gas = evapourating Liquid to Soldid is Freezing Gas to liquid is condensing Solid to gas is sublimation
What are the arrangements of the states of matter?
Solid- regular lattice, Strong forces of attraction, definite shape and volume, expand slightly when hot as they vibrate in their fixed positions
Liquid- some forces of attraction, free to move past each other, keep same volume but different shape, random motion, faster when hotter so expand
Gas- no forces of attraction, travel in straight line and only react when they collide, hot is more energy so more collisions so expand and pressure increases, flow into a container
Describe the movement and energy of particles in a state change
When the particles gain more energy when heated and makes it vibrate more and weakens forces between the particles so they expand. At certain temp these particles break free.
Whats the difference between a pure substance and a mixture
A pure substance has one specific melting and boiling point whereas a mixture has many
A pure substance is made up of one element or a compound such as water.
How can you test for purity using melting points?
compare its melting point of sample to its expected value
State one mixture which is separated by filtration
Salt water (insoluble solid from a liquid)
Mixtures that can be separated with crystallisation
A soluble solid from a liquid
How do crystals form in crystalisation
put mixture into evaporating dish and heat to evaporate the water. when you see crystals form leave it to cool and evaporate.
Salt crystals form as it becomes a cold highly concentrated solution
How do you separate a mixture with filtration
Take the mixture and a filter funnel and filter paper and fold into a cone shape and poor mixture into funnel carefully so it leaves behind the solid residue.
How can mixtures be separated with chromatography?
Draw line on bottom of paper in pencil as its insoluble and put a dot of the ink on the line. this line must be above water level so it doesn’t wash off. leave in glass beaker and measure the distance traveled. put lid on to stop evaporation.
What is the Rf value?
distance traveled by solute / distance traveled by solvent
solute is baseline to spot
Describe simple distilation
separates solutions eg sea water
have flask with bung in top and thermometer with solution in. heat it gently so when the water reaches its boiling point the steam rises to the condenser and cools to make pure water in the beaker at the other end.
What is the difference between simple and fractional distillation?
Fractional separates mixtures with a range of boiling points such as crude oil. simple is to separate a liquid from a solution
How do you carry out fractional distillation?
Take a mixture such as crude oil and fractionating column with glass rods and heat the solution so the lowest boiling point mixture condenses first so you collect it in a test tube. raise the temp after collecting each fraction.
Why must water used in chemical analysis not contain salts?
It needs to be deionised so ions such as calcium in tap water must be removed from tap water as using normal water could interfere with your result. So if you want to dissolve something in water the water must be pure!
