Chemical Analysis

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  • Created by: 07BO02
  • Created on: 21-01-18 19:27
What is a pure substance?
A substance that only contains one compound or element throughout.
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What do impurities do the melting point and boiling point of a substance?
Impurities lower the melting point and increase the boiling point of substance. They also increase the melting range of the substance.
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What is a formulation?
A useful mixture with a precise purpose that are made with a formula. Each component is in a measured quantity and contributes to the properties of the mixture so it achieves its purpose.
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What's the test for chlorine?
Chlorine bleaches damp litmus paper white. (It can turn blue litmus paper red for a moment because chlorine is acidic.)
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What's the test for oxygen?
If you put a glowing splint inside a test tube containing oxygen, the oxygen will relight the glowing splint.
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What's the test for carbon dioxide?
Bubbling carbon dioxide through limewater (calcium hydroxide solution) causes the limewater to turn cloudy.
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What's the test for hydrogen?
If you hold a burning splint at the open end of a test tube containing hydrogen, you'll hear a squeaky pop.
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Why does hydrogen make a squeaky pop?
Hydrogen reactive and the noise comes from a mini-explosion made by hydrogen burning quickly with oxygen to form water.
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What is the mobile phase in chromatography?
This is where the molecules can move; it's always a liquid or a gas. (e.g. a solvent like water)
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What is the stationary phase in chromatography?
This is where the molecules can't move: it's usually a solid or really thick liquid. (e.g. chromatography paper)
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What's the formula for calculating Rf values?
Rf = distance traveled by substance / distance traveled by solvent
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How do you test for carbonates?
You add a few drops of dilute acid to the mystery substance in a test tube. Then connect that test tube to a test tube containing lime water and observe whether it turns cloudy.
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How do you test for sulfates?
You add a few drops of dilute hydrochloric acid (HCl) followed by a few drops of barium chloride solution (BaCl2) to a test tube containing the mystery substance.
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What colour precipitate is formed if sulfate ions (SO4 2-) are present?
A WHITE precipitate of barium sulfate.
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How do you test for halides?
You add a few drops of dilute nitric acid (HNO3) followed by a few drops of silver nitrate solution (AgNO3) to the mystery solution.
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What colour precipitate is formed if chloride ions (Cl-) are present?
A WHITE precipitate of silver chloride.
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What colour precipitate is formed if bromide ions (Br-) are present?
A CREAM precipitate of silver bromide.
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What colour precipitate is formed if iodide ions (I-) are present?
A YELLOW precipitate of silver iodide.
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What's the flame colour of lithium ions (Li+)?
Lithium ions produce a CRIMSON flame.
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What's the flame colour of sodium ions (Na+)?
Sodium ions produce a YELLOW flame.
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What's the flame colour of potassium ions (K+)?
Potassium ions produce a LILAC flame.
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What's the flame colour of calcium ions (Ca 2+)?
Calcium ions produce an ORANGE-RED flame.
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What's the flame colour of copper ions (Cu 2+)?
Copper ions produce a GREEN flame.
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Other than flame tests, how do you test for different metal ions?
You add a few drops of sodium hydroxide (NaOH) to the mystery substance in hope of forming a coloured insoluble hydroxide.
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What colour precipitate is formed if calcium ions (Ca 2+) are present?
A WHITE precipitate of calcium hydroxide.
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What colour precipitate is formed if copper(II) ions (Cu 2+) are present?
A BLUE precipitate of copper(II) hydroxide.
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What colour precipitate is formed if iron(II) ions (Fe 2+) are present?
A GREEN precipitate of iron(II) hydroxide.
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What colour precipitate is formed if iron(III) ions (Fe 3+) are present?
A BROWN precipitate of iron(III) hydroxide.
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What colour precipitate is formed if aluminium ions (Al 3+) are present?
A WHITE precipitate of aluminium hydroxide at first but then re dissolves in excess NaOH to form a colourless solution/
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What colour precipitate is formed if magnesium ions (Mg 2+) are present?
A WHITE precipitate of magnesium hydroxide.
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What happens in the process of flame emission spectroscopy?
A sample is placed in a flame and the ions' electrons become excited as the ions heat up. When the electrons drop back to their original energy levels, they release light energy which passes through a spectroscope to produce a line spectrum.
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Why do all ions have different line spectra?
No two ions have the same charge and electron arrangement so no two ions will emit the same exact combinations of light wavelengths - causing them to have different line spectra.
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What does the intensity of the spectrum indicate?
The intensity indicates the concentration of that ion in the solution.
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What are 3 advantages of using instrumental analysis?
1) They are very sensitive 2) They are very fast 3) They are very accurate
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Other cards in this set

Card 2

Front

What do impurities do the melting point and boiling point of a substance?

Back

Impurities lower the melting point and increase the boiling point of substance. They also increase the melting range of the substance.

Card 3

Front

What is a formulation?

Back

Preview of the front of card 3

Card 4

Front

What's the test for chlorine?

Back

Preview of the front of card 4

Card 5

Front

What's the test for oxygen?

Back

Preview of the front of card 5
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