Introduction To Chemistry (including Seperating Techniques) Flashcards
What is a mixture?
Two or more different atoms not chemically bonded together
How can we separate a mixture?
By physical means such as:
Changing the temperature
Dissolving part of the mixture into a solvent such as water
How can we determine weather a substance is pure?
Pure substances have sharp melting and boiling points
What method do we use to separate a solid from a liquid?
Filtration - leaves us with residue and filtrate
What method do we use to separate a solute from a solution?
Crystallisation
What method do we use to separate the components of a solution?
Simple distillation - water boils and is condensed back to a liquid by the condenser, the salt remains in the flask
What method do we use to separate a mixture of liquids?
Fractional distillation - takes advantage of the different boiling points
What method do we use to separate a variety of mixtures?
Paper chromatography
What observations should we make when describing substances?
.state (solid liquid or gas)
.coloured/colourless
.crystalline/powdered (solids)
.clear/cloudy (liquids)
What observations should we make when describing changes?
.any effervescence?
.has a solid appeared or disappeared?
.colour change?
.any unusual sounds or smells?
Characteristics of a physical change?
.no new substances created
.are usually easy to reverse
.absorb or release small amounts of energy
Characteristics of a chemical change?
.create new substances
.are usually difficult to reverse
.absorb or release large amounts of energy
Describe a chemical test for water
Anhydrous copper sulphate turns from white to blue
.tells you that water is present but jot how pure it is
Describe two physical tests for water
Melting point - 0C
Boiling point - 100C
Purer water matches these properties more closely
What is an element
A substance containing only one type of atom
Metallic properties
High MP/BP
Electrical conductors
Malleable
Shiny
Non metal properties
Low MP/BP
Electrical insulators
Brittle
Dull
What is a compound?
A substance containing more than one type of atom chemically bonded together
How can we make compounds?
Heating elements together
Give an example of two elements that hen form a compound have completely different properties
Sodium (corrosive metal) + chlorine (toxic gas) —> sodium chloride (salt)
What are the three types of compounds?
Metallic, ionic and covalent
How do you make a metallic compound?
Two metals
How do you make an ionic compound?
Metal and non metal
How do you make a covalent compound?
Two non metals
What is a solute?
The substance which is going to be dissolved
What is a solvent?
The substance which is going to do the dissolving
What is a solution?
The resulting mixture of a solute dissolved in solvent
What does saturated mean?
A solution which no more solute can be dissolved
What is a suspension?
A solid floating in a liquid because it cannot be dissolved
What does soluble mean?
A substance which can be dissolved
What does insoluble mean?
A substance which cannot be dissolved
How do we measure solubility?
In g per 100g of solvent
