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Chemistry unit 3 > analysis and synthesis > Flashcards

analysis and synthesis Flashcards

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0
Q

What colours do the metals make in flames tests

A 
Lithium - Crimson 
Sodium - yellow 
Potassium - lilac
Calcium - red 
Barium - green
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1
Q

What are flame test used for?

A

Identify metal ions

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2
Q

What is the test for positive ions?

A

sodium hydroxide solution:

  1. place solution of sample in test tube
  2. add sodium hydroxide solution and look for precipitate
  3. add excess sodium hydroxide solution do see if precipitate redissolves
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3
Q

What do the samples produce in test with sodium hydroxide?

A 
calcium - White precipitate 
magnesium - White precipitate 
aluminium - White precipitate ( redissolves with excess)
Copper - blue precipitate 
Iron (II) green precipitate 
Iron (III) brown precipitate
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4
Q

What is the test for carbonate ions?

A
  1. Add dilute acid

fizzes and produces CO2 = carbonate ions

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5
Q

What is the test for halide ions?

A
  1. Place solution of sample in test tube
  2. Add dilute nitric acid
  3. add silver nitrate solution

Silver chloride = White precipitate
Silver bromide = cream precipitate
Silver iodide = yellow precipitate

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6
Q

What is the test for sulfate ions?

A
  1. Place solution of sample into test tube
  2. add hydrochloric acid
  3. Add barium chloride solution

White precipitate = sulfate ions

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7
Q

What are titrations used for?

A

to find volumes of acid and alkali solutions that react in a neutralisation reaction

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8
Q

what is the method of a titration?

A
  1. Use pipette to accurately measure volume of acid then place in conicle flask
  2. Add indicator to acid
  3. Full burette with alkali and then gradually add to flask
  4. Swirl until indicator changed colour and end point has been reached
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9
Q

How is concentration calculated when mass or miles are known?

A

concentration = mass or moles/ volume

conc - g/dm3 or mol/dm3
Volume - cm3 or dm3

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10
Q

When is M1V1 used?

A

when no big numbers in equation

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11
Q

What is the Haber process?

A

manufacture of ammonia using nitrogen from air and hydrogen from natural gas or other sources

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12
Q

How is the haber process carried out?

A

gases passed over iron catalyst at about 450^c and 200 atmospheres

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13
Q

What type of reaction is Haber process?

A

REVERSIBLE

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14
Q

What happens on cooling?

A

ammonia liquified and is removed. Remaining nitrogen and hydrogen recycled

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15
Q

When can’t reactants and products escape?

A

In a closed system

16
Q

How is equilibrium reached?

A

When a reversible reaction occurs in a closed system equilibrium is reached the rate of forwards reaction is equal to rate of backwards reaction

17
Q

What happens at equilibrium?

A

both reactions continue to happen but amount of reactants and products remain constant

18
Q

How can amounts of reactants and products be changed for a reversible reaction?

A

changing reaction conditions

19
Q

When does changing pressure effect equilibrium?

A

in reversible reaction when different numbers of molecules on one side of equation

20
Q

What happens if the forwards reaction produces more molecules of gas?

A

increase in pressure decreases amount of products formed and vice versa

21
Q

What happens if the forwards reaction produced fewer molecules of gas?

A

increase in pressure means increase in amounts of products formed and vice versa

22
Q

What happens if the forwards reaction is exothermic?

A

increase in temperature means decrease in amount of products formed and vice versa

23
Q

What happens if the forwards reaction is endothermic?

A

Increase in temperature means increase in amount of products formed

24
Q

What affect do catalysts have on equilibrium?

A

NO EFFECT

25
Q

What does an increase in pressure mean for Haber process and why?

A

Increased yield because the forwards reaction produces fewer molecules of gas

26
Q

why is 200 atmospheres used?

A

good yield but not too high so less money spent of building and maintenance

27
Q

What does a decrease in temperature mean for the Haber process?

A

increased yield because forwards reaction exothermic

28
Q

Why is 450^c used?

A

good yield but also fast rate of reaction

Chemistry unit 3 (5 decks)

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