Chemical analysis Flashcards

1
Q

What is a pure substance

A

A substance with only one type of atoms or molecules, not mixed with anything else

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2
Q

How can you tell if a substance is pure

A

If it only melts or boils at one specific temperature
Then compare the temperature it boils at to a data book

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3
Q

What effect do impurities have on melting range

A

It makes the melting range bigger i.e makes boiling points higher and melting point lower

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4
Q

What is a formulation

A

A mixture that is designed for a specific purpose.
The components in the formulation are at a specific ratio to ensure the formulation can do its purpose

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5
Q

What is 2 examples of a formulation

A

Paint and resin

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6
Q

What is chromotography

A

A method to seperate substances in a mixture

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7
Q

What is the mobile phase in chromotography

A

A state in which molecules can move- either liquid or gas

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8
Q

What is the stationary phase

A

A state in which molecules cannot move- A solid or thick liquid

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9
Q

How do you calculate Rf

A

Distance travelled by Substance /
Distance travelled by Solvent
It is always less than 1

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10
Q

How do you test for chlorine

A

Damp blue litmus paper will turn white

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11
Q

How do you test for Oxygen

A

It will re- light a glowing splint

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12
Q

How do you test for carbon dioxide

A

Limewater will turn cloudy

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13
Q

How do you test for hydrogen

A

Use a lit splint and a tube of hydrogen
The hydrogen will make the lit splint make a squeaky pop sound

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14
Q

How can you test for Carbonates

A

Add some dilute acid to the sample
Connect the tube to a vile of limewater
If the limewater goes cloudy then there was carbonates presentas CO2 was released

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15
Q

How can you test for sulfates

A

Drop some dilute HCl (to purify)
Drop some barium chloride solution
The barium chloride should react with the sulfate and a white precipitate of barium sulfate should form.

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16
Q

How can you test for halides

A

Add Nitric acid and silver nitrate to the mytery solution
Chlorine gives a white precipitate
Bromine gives a crean precipitate
Iodine gives a yellow precipitate

17
Q

What is a flame test

A

When you put a piece of metal in a flame and it comes out as a different colour and you can work out what metal it is

18
Q

Give the results for all the flame tests

A

Li- Crimson
Ca- Orange
Na - Yellow
Cu- Green
K- Lilac

19
Q

What is the method of doing a flame test

A

Dip a platinum loop into Hcl then hold it ontop of a bunsen burner until there is no coloured flame anymore.
Dip the loop into the sample and then put it into the flame to see the colour change

20
Q

What substance do you use for finding metal hydroxide precipitates

A

Sodium hydroxide

21
Q

What is the colour of calcium precipitate when mixed with sodium hydroxide

A

White

22
Q

What is the colour of Copper precipitate when mixed with sodium hydroxide

A

Blue

23
Q

What is the colour of Iron II precipitate when mixed with sodium hydroxide

A

Green

24
Q

What is the colour of Iron III precipitate when mixed with sodium hydroxide

A

Brown

25
Q

What is the colour of Aluminium precipitate when mixed with sodium hydroxide
When you add excess what colour is it

A

First it is white
When excess is added it turns colourless

26
Q

What is the colour of Magnesium precipitate when mixed with sodium hydroxide

A

White

27
Q

What is the method of flame emission spectroscopy

A

The sample is put into a flame and the light given out is passed
through a spectroscope.
The output is a line spectrum that can be
analysed to identify the metal ions in the solution and measure their
concentrations.

28
Q

What are advantages of using flame emission spectroscopy over normal methods

A

Its more sensitive
Its faster
Its more accurate
Its not subject to opinion