elements compounds mixtures Flashcards
Definition of an element
Element is a substance that consists of only one type of atom
And can not be split into anything simpler by chemical means
Definition of a compound
Substances of where two or more diff elements are chemically combined
What is a molecule
A substance made of two or more atoms chemically combined
What is a pure substance
A substance that contains only one type of element of compound
How do you distinguish between the purity of a substance in terms of melting and boiling points
Pure substances melt and boil at specific temperatures
If it has a range of melting points it is impure
If you have a gradual decrease in temperature during change of state, what does that suggest about the purity of a substance and why
It is impure because it’s melting and boiling points have a range
Explain why compounds are always pure
Although they have more than one type of atom, the ratio is always in fixed compositions
Give an example of elements that explains how elements have different properties in mixtures and compounds
Mixture of hydrogen and water is a gas the explodes
Compound of hydrogen and water is water
What will adding salt to water do to the melting and boiling point of water and why
The melting point will decrease and the boiling point will increase due to the presence of impurities
What is the residue and what is the filtrate
The residue is what’s left on the filter paper
The filtrate is what seeps through
What two types of mixtures can you separate while using filtration
Insoluble solid from a liquid
Liquid from an insoluble solid
What method of separation can you use to separate a solute from a solution
Crystallization
When heating an evaporating basin in crystallization, what are we waiting for and how do we test it
Waiting till there is a saturated solution of crystals,
Test it using a glass rod
Give a reason why simple distillation may be better to use than crystallization when trying to separate a solution
The water is also able to be collected rather than evaporating
Why is it best to provide the water going in from the bottom in distillation
the pressure allows the jacket to always be full
What is a better alternative to a Bunsen burner and why
Heating mantle because you can control temperature
What is a miscible liquid
Liquids that mix together
What does a condenser contain and what does it condense
Condenser contains circulating cold water
Condenses vapor
In fractional distillation, which liquid condenses first
The liquid with a lower boiling point
What is the solvent front
The highest level of the solvent on the paper
If the dye does not move up from the solvent line, what does that say about its solubility and the solvent that you’ve used
The dye is not soluble in the solvent used
- you need to use a different solvent
What does it mean if a substance has high affinity for paper
It sticks well to the paper
When talking about results of a chromatogram, why do you describe the number of dyes as “minimum” (of say three)
Because there could be more dyes which perhaps travelled the same distance and have the same color
Why do substances in a mixture each move up at different rates in chromatography and why
Because they have different attractions the the mobile and stationary phase
- due to their properties
