chemistry

  • Created by: EveKay
  • Created on: 05-01-18 09:15

what apparatus do u need for separating a salt fro

Apparatus:

  • Funnel
  • Spatula
  • Mixture of sand and salt
  • Filter paper
  • Chronical flask
  • Bunsen burner
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atoms

Atoms are the smallest particle of anything that can exist on its own.  Atoms are made up of even smaller particles called protons, neutrons and electrons.

Mass number = protons + neutrons

Atomic number = protons

There is the same amount protons as electrons.

Amount of neutrons = mass number - atomic number

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whats steps to separate a salt?

Steps

Step 1 : add water to the mixture so the salt can dissolve into the water

Step 2 : they you filter the mixture through the funnel with the filter paper in it. The salt will be left in the water in the chronical flask.

Step 3 : Then heat the salt water so that the water evaporates leaving just the salt in the flask.

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summary of separating a salt?

Summary

The sand and salt is a mixture; we then add water to dissolve the salt. The sand is insoluble and the salt is soluble.  The mixture was filtered and the sand was the residue in the filter paper.  The water was evaporated from the solution to leave the salt behind.

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ionic compounds

Ionic compounds make giant ionic lattices.  Positive and negative ions alternate.  There are strong electronic forces of attraction between positive charged ions. Ionic solids do not conduct as the ions are not free to move.  Ionic compounds are good conductors when they are liquid (molten) for solution because the ions are now more freely than when they where in the solid formation. 

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covalent bonding

A covalent bond is when a pair of electrons are shared between two atoms.  If two pairs of electrons are shared this is called a double covalent bond.  These happen between non-metal atoms.  Atoms bond this way in order to achieve a full outer shell of electrons.

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simple molecular substances

Non-metal atoms bond with other non-metal atoms to form simple molecules.  Atoms in the molecule are held together by strong covalent bonds. An example of a simple molecule is water.  Simple molecular substances have low melting and boiling points.  They have low melting and boiling points because between the molecules there are weak intermolecular forces.  Simple molecular substances don’t conduct electricity.  This is because the molecules have no charge on the.

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exothermic reactions

Exothermic reactions

  • Products have less chemical energy than the reactants
  • Activation energy = minimum energy needed to react
  • Overall, the temperature gets hotter because: chemical energy = heat energy
  • In calculations, the energy change of an exothermic reaction is negative. E.g. burning methane = -890KJ/mol
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endothermic reactions

Endothermic reactions

  • Products have more chemical energy than the reactants.
  • Activation energy = minimum energy needed to react
  • Overall, the temperature gets colder because: heat energy = chemical energy
  • In calculation, the energy change for an endothermic reaction is positive, e.g. reaction of sodium hydrogen carbonate with hydrochloric acid  = +30KJ/mol
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catalysts

Catalysts

  • Activation energy = minimum energy needed to react
  • Catalyst = substance that speeds up an reaction but does not get used up
  • A catalyst works by providing an alternate route with a lower activation energy.
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displacement reaction

Displacement

The most reactive metal was magnesium because magnesium displaced all of the other three metals. The least reactive metal was copper because copper couldn't displace any of the other metals. In a displacement reaction, the more reactive the metal is the metal loses electrons to become a positive ion.  This is called oxidation.  The less reactive the metal is more it gains electrons to change from a positive ion to a metal atom.  This is called reduction.

Oxidation

Is

Loss of electrons

Reduction

Is

Gain of electrons

Metal reactivity

When metals react with each other substances like copper, water and acids, the metal atoms lose electrons to form and gain positive ions.  The more easier a metal atom can lose electrons, the more reactive that metal is.  For example, potassium  loses electrons to get K+, easier than when magnesium loses two electrons to get Mg2+.  This means that potassium is more reactive than magnesium.

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making soluble salts theory

  • Salts are important substances with many uses.  Many re used as medicines or in the production of food.  It is important that when we make salts that we can produce pure salts.
  • Salts are made when acids react with metals or with bases.
  • Some salts are soluble in water and some are not.  We are looking at how to make salts that are soluble in water.
  • It is easiest to make soluble salts using a metal or an insoluble base.
  • It is vital that there is no left over acid and no left over metal/base mixed in with the salts.

Step 1

  • React acid with an insoluble substance (e.g. a metal, metal oxide, metal carbonate) to produce the salt
  • The mixture may need to be heated
  • Add the insoluble substance until it no longer reacts

Step 2

  • Filter off the left over metal / metal oxide / metal carbonate

Step 3

  • Heat the solution to evaporate some water until crystals start to form (possibly using a water bath)
  • Leave the solution to cool down - more crystals will form as it cools
  • Filter off and wash the crystals of the salt
  • Allow the crystals to dry
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electrolysis

Electrolysis is the breaking down of an ionic substance using electricity.  The substance that is broken down is called the electrolyte.  The substance must be a state of a liquid in order to conduct electricity because the ions are free to move so a solid's ion are not free to move therefore it doesn't conduct electricity.

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