4. Chemical Analysis Flashcards

1
Q

What defines a pure element?

A

A pure element contains only one substance with no other substances mixed in.

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2
Q

How can you assess the purity of a substance?

A

Purity can be assessed using melting point and boiling point information.

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3
Q

Why are measures of purity important?

A

Measures of purity are important in everyday substances such as foodstuffs and drugs.

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4
Q

What is a mixture?

A

A mixture consists of two or more elements or compounds not chemically combined, retaining their individual properties.

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5
Q

How can the substances in a mixture be separated?

A

Substances in a mixture can be separated by physical methods, including distillation, filtration, and crystallization.

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6
Q

What is paper chromatography used for?

A

Paper chromatography is used to analyze substances present in a solution, such as food colorings and inks/dyes.

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7
Q

How do you carry out paper chromatography?

A

Place a spot of the solution on chromatography paper, dip the paper in solvent, and allow the solvent to rise, separating the components.

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8
Q

What is the Rf value in chromatography?

A

The Rf value is the ratio of the distance moved by the compound to the distance moved by the solvent front.

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9
Q

What are the phases in chromatography?

A

Chromatography involves a stationary phase and a mobile phase, with separation depending on the relative solubility of the components.

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10
Q

How can chromatography distinguish pure from impure substances?

A

Pure substances show one spot, while impure substances show multiple spots.

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11
Q

What is the test for hydrogen gas?

A

A pop is heard when a lighted splint is placed near hydrogen gas.

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12
Q

What is the test for oxygen gas?

A

A glowing splint relights in a test tube of oxygen gas.

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13
Q

What is the test for carbon dioxide?

A

Carbon dioxide turns limewater (calcium hydroxide solution) cloudy white.

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14
Q

What are the properties and tests for ammonia gas?

A

Ammonia has a sharp, choking smell, turns damp red litmus paper blue, and forms white smoke of ammonium chloride with hydrogen chloride gas.

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15
Q

What are the properties and tests for chlorine gas?

A

Chlorine has a sharp, choking smell, turns damp blue litmus paper red, and then bleaches it white.

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16
Q

What colors do lithium, sodium, potassium, calcium, and barium produce in flame tests?

A

Lithium: crimson
Sodium: yellow
Potassium: lilac
Calcium: red
Barium: green.

17
Q

What ions form white precipitates with sodium hydroxide solution, and which one dissolves in excess?

A

Aluminium, calcium, and magnesium ions form white precipitates; only aluminium hydroxide dissolves in excess sodium hydroxide.

18
Q

What are the colors of the precipitates formed by copper(II), iron(II), and iron(III) ions with sodium hydroxide?

A

Copper (II): blue
Iron (II): green
Iron (III): brown.

19
Q

How do carbonates react with dilute acids, and how can carbon dioxide be identified?

A

Carbonates react with dilute acids to form carbon dioxide, which turns limewater cloudy white.

20
Q

What precipitates do halide ions form with silver nitrate solution in the presence of dilute nitric acid?

A

Silver chloride: white
Silver bromide: cream
Silver iodide: yellow.

21
Q

What is the test for sulfate ions in solution?

A

Sulfate ions produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid