C1 + C2 A Flashcards
Law of Conservation of Mass
Total mass of products = total mass of reactants
How can the law of Conservation of Mass be broken?
In reactions involving gases, this law can appear to be broken when the reactions are carried out in open containers, like test tubes and conical flasks
Solution
A mixture of a liquid(solvent) and one/more dissolved solids(solutes)
Solvent
A liquid that dissolves certain solutes to make a solution
Solute
A solid that can be dissolved in solvent to make a solution
Soluble
Can be dissolved in a given solvent
Insoluble
Cannot be dissolved in a given solution
What separation technique is used for mixtures with liquids and insoluble solids?
Filtration
How does filtration occur?
1) A mixture is poured into the filter funnel, which has folded filter paper, and is designed to let liquids pass through, but stop solids passing through
What filtration technique separates a solvent from a solution?
Distillation
Processes of distillation
1) The solution is poured into a round-bottomed flask, connected to a condenser in a closed system to prevent the loss of gases.
2) The solution is heated - the liquid solvent boils into a gas.
3) The gas cools and condenses in the condenser back into a liquid(distillate) collected, but the solid solute remains as residue on the inside of the round-bottomed flask.
What collection technique would be used when the solute doesn’t break down at high temperatures?
Evaporation - separates the solute from a solution
How does evaporation occur?
1) The solution is poured into an evaporating basin and heated.
2) The liquid solvent boils off, leaving the solid solute as residue in the evaporating basin
What techniques separate a solute from a solution?
Evaporate
Crystallisation
What collection technique is used when the solute will thermally decompose at high temperatures?
Crystallisation
What happens in crystallisation?
The solution is gently heated in an evaporating basin, meaning liquid solvent evaporates and crystals form, which then are left to cool, so crystals of the solute form in the residual solution. Once cool, remaining solution is removed by filtration and the crystals are dried.
What technique can be used to separate a mixture of two or more liquids with different boiling points?
Fractional distillation
What technique is used to separate mixtures according to the solubility of the components?
Chromatography
What does Dalton suggest about the history of the atom?
Atoms are tiny, hard spheres that can’t be divided or split
Also that each chemical element had its own atoms that differed from others in their mass
What did JJ Thompson suggest about the history of the atom!
He suggested in an atom, there are tiny negatively charged electrons embedded in a cloud of positive charge, with atoms carrying no overall charge.
What did Rutherford suggest about the history of the atom?
Electrons are orbiting around a mucleus, with dense positively charged protons
What did Niels Bohr suggest about the atomic model?
Electrons orbit the nucleus at set distances, in certain fixed energy levels/shells
What did James Chadwick suggest about the atomic model?
That the nucleus also contains the sub-atomic particle neutron - with no charge and the same mass of a proton, because this explained the missing mass noticed in atoms at the time.
What’s the charge of the nucleus?
An overall positive charge, since it contains protons with a positive charge, but neutrons with no charge
Atomic number
The number of protons in each atom of an element
Where is the mass of an atom concentrated?
In the nucleus, protons and neutrons have the same relative mass(1), electrons are very light
How are the elements in the periodic table arranged?
In order of their atomic number
Ion
A charged atom/group of atoms
Isotopes
Atoms of the same element with different numbers of neutrons
What is the impact of extra neutrons on isotopes?
Extra neutrons make the nucleus unstable, so an isotope may he radioactive
Samples of different isotopes of an element have different physical properties(e.g. different density and level of radioactivity, but they have the same chemical properties as their atoms have the same number of protons + electrons).
What is the lowest energy level shown by shells of electrons?
The lowest energy level is shown by the shell nearest to the nucleus and the electrons in an atom occupy the lowest available energy level, the highest energy level is shown by the outermost shell in an atom.
What determines the way a particular element reacts?
The number of electrons in the outermost shell of an element’s atoms determine the way in which the element reacts and the overall chemical properties of an element
Which liquid will be collected first in fractional distillation?
The liquid witn the lowest boiling point
Paper chromatography
1) Draw a line near the bottom of a sheet of filter paper with a pencil(pencil marks are insoluble and won’t dissolve in the solvent).
2) Add a spot of the ink to the line and place the sheet in a beaker of dolvent e.g. water.
3) Ensure the ink isn’t touching the solvent - you don’t want to dissolve it.
4) Place a lid on top of the container to stop the solvent evaporating.
5) The solvent seeps up the paper, carrying the in, with it.
6) Each different dye in the ink will move up the paper at a different rate, s9 the dyes will separate out.
7) If any of the dyes in the ink are insoluble, they’ll stay on the baseline.
8) When the solvent’s nearly reached the top of the paper, take the paper out of the beaker and leave it to dry.
9) The end result is a pattern of spots called a chromatogram.
