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IGCSE Chemistry > Alt to prac > Flashcards

Alt to prac Flashcards

1
Q

what type of indicator to use in titration

A

methyl orange, phenophalein (only one end point)

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2
Q

why do we not use universal indicator in titration

A

has a range of colours (no set end point)

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3
Q

how and why do we heat alcohols

A

with a naked flame, in a water bath. naked flame because alcohols are extremely volatile

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4
Q

describe the experiment to reduce copper (III) oxide to copper

A

powdered solid and add heat and attach bung and delivery tube to provide dry hydrogen to the powedered solid.

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5
Q

how to test for products of combustion

A

burning material, filter funnel above flame, attach filter funnel to bung attached to delivery tube of limewater, and then another delivery tube to anhydrous copper sulfate (tests for CO2 and water)

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6
Q

how to test for rust

A

test tube 1 = air and oxygen
test tube 2 = oil and boiled water (no air)
test tube 3 = calcim chloride (no water)

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7
Q

what factors affect rate of reaction

A
  • different temperature acid
  • different sizes of reactants/particles
  • concentration of acid
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8
Q

how to measure timing when insoluble thing is forming

A
  • measure how long it takes for cross to disappear
  • change temp/conc of acid
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9
Q

constant variables in acid reaction

A
  • cross
  • diameter of beaker
  • volume
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10
Q

what to do if there are large lumps

A

use pestle and mortar to crush

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11
Q

what physical things should you mention

A
  • apparatus
  • exact volume/mass
  • chemical/substance
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12
Q

what you could possible do to get more marks

A

labelled diagram

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13
Q

what you should do when saying what you’re doing

A

state what experiment you will carry out

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14
Q

what is the principle of chromatography

A

difference in solubility that seperates different substances

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15
Q

what is stationary phase

A

the one which does not move with the sample

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16
Q

what is the mobile phase

A

one which moves with the sample

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17
Q

what does Rf mean

A

retention factor

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18
Q

how to figure out the Rf value?

A

distance moved by solute/distance moved by solvent

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19
Q

how to make colourless substances visible during chromatography

A
  • dry chromatogram in oven
  • spray with locating agent
  • heat for 10 minutes in the oven
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20
Q

what is the water level

A

mobile phase

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21
Q

what is the chromatography paper

A

stationary phase

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22
Q

why do we draw line in pencil during chromatography

A

it is insoluble

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23
Q

how to do filtration

A
  • mixture goes in a funnel with filter paper into a flask
  • residue is insoluble, filtrate goes through
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24
Q

how to do crystallization

A
  • some water in solution is evaporated (solution becomes more concentrated
  • solution left to cool and crystallise (solubility decreases as temperateure decreases)
  • crystals are filtered to remove solvent
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25
Q

how can we obtain pure dry crystals from the filtrate (COMMON QUESTION)

A
  • pour filtrate into the evaporating basin and heat
  • leave to evaporate and let it cool to crystallisation point
  • wash crystals with distilled water
  • dry it between filter paper
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26
Q

process of simple distillation

A
  • impure liquid is heated
  • boils and steam rises into condenser
  • impurities left behind
  • condenser = cold so steam condenses to pure liquid and drops into the beaker
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27
Q

what is fractional distillation

A

removes a liquid from a mixture of liquids because liquids have different bp

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28
Q

process of fractional distillation

A
  • mixture is heated to evaporate substance with lowest bp (some other liquids evaporate too)
  • beads are heated to the boiling point of the lowest substance being removed cannot condense on beads
  • other substances continue to condense (drip back into flask)
  • beaker = changed after every fraction
  • thermometer placed on the top of fractional distillation column to measure TEMPERATURE OF THE VAPOUR INSTEAD OF THE LIQUID
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29
Q

how to do acid-base titration

A
  • place known volume of alkali using volumetric pipette into a conical flask
  • add indicator (e.g. thymolphthalein)
  • titration: add acid using burette until end point reached
  • record volume of acid added
  • repeat without indicator
  • transfer to evaporating basin
  • heat with bunsen burner
  • leave to cool at crystallisation point
  • was crystals with distilled water
  • dry crystals on filter paper
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30
Q

what is filtration used to seperate

A

solid from a liquid

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31
Q

what is evaporation used to seperate

A

solid from a solution

32
Q

what is crystallization used to seperate

A

solid from a solution

33
Q

what is simple distillation used to seperate

A

solvent from a solution

34
Q

what is fractional distillation used to seperate

A

liquids from each other

35
Q

what is chromatography used to seperate

A

different substances from a solution

36
Q

making salts (metal and insoluble base) describe metal process

A
  • warm acid (increases speed of reaction)
  • add excess reactant and stir
  • filter mixture
  • transfer to evaporating basin
  • heat using bunsen burner
  • leave to cool until crystallisation point
  • wash crystals with distilled water
  • dry crystals on filter paper
37
Q

making salt (metal and insoluble base) describe insoluble base process

A
  • add insoluble base to acid and heat gently (it will dissolve)
  • keep adding until no more dissolves (reaction is done)
  • filter out insoluble/excess base
38
Q

process of precipitation to form an insoluble salt

A
  • mix 2 soluble salts together so they react
  • filter mixture to the products produced (soluble and insoluble salt produced)
  • wash insoluble salt with distilled water
  • dry insoluble salt between filter paper
39
Q

color of methyl orange in acidic and alkaline conditions

A

acidic = red
alkaline = yellow

40
Q

colour of phenolphthalein in acidic and alkaline conditions

A

acidic = colourless
alkaline = pink

41
Q

colour of copper(II) sulfate

42
Q

colour of copper (II) oxide

43
Q

colour of copper (II) carbonate

44
Q

colour of manganese (IV) oxide

45
Q

colour of iron(II) salts

A

pale green

46
Q

colour of iron (III) salts

A

brown/orange

47
Q

liquid is touched with a lighted splint and burns with a blue flame. what is the liquid

A

organic fuel

48
Q

what does it mean if it says ‘ condensation forms on the side of the test tube’

A

it is hydrated

49
Q

process of flame testing

A
  • dip unreactive metal into concentrated acid and hold it in the blue blame of bunsen burner until no colour change
  • dip loop of the solid sample and and place it on the edge of blue bunsen flame
50
Q

how is bunsen burner. adjusted to give scorching flame

A

by opening the air hole to increase air supply

51
Q

what is test for ammonia and positive result

A

damp red litmus paper turns blue

52
Q

test for sulfur dioxide and positive result

A

turns acidified aqueous potassium manganate (VII) from purple to colourless

53
Q

colour of anhydrous and hydrous copper sulphate

A

anhydrous: white
hydrated = blue

54
Q

colour of anhydrous and hydrous cobalt (II) chloride

A

anhydrous = blue
hydrous = pink

55
Q

error: no repeats
improvement?

A

repeat 3 times

56
Q

error: different colour changes
improvement?

A

use colorimeter

57
Q

error: measuring cylinder is inaccurate
improvement?

A

use pipetter because it is more accurate

58
Q

error: adding past endpoint
improvement?

A

add volume in smaller quantities

59
Q

error: temperature/heat loss
improvement:

A

use thermostatically controlled water bath

60
Q

error: same measuring cylinder used in multiple investigations
improvement?

A

use different measuring cylinders

61
Q

when do we use downward delivery for gas collection

A

when gas is more dense than air (CO2, SO2, HCL (g) )

62
Q

when do we use upward delivery for gas collection

A

when gas is less dense than air (ammonia, hydrogen)

63
Q

when do we use collection overwater for gas collection

A

when gas is sparingly soluble in water (CO2, H2, O2)

64
Q

when do we use gas syringe for gas collection

A

to measure volume for any type of gas

65
Q

graph requirements

A
  • sharp pencil
  • label both axis
  • labels should be in form ‘quantity/units’
  • appropriate scale
  • use crosses to mark data points for scatter graphs
  • line of best fit
  • do not join data plots for scatter
66
Q

why does graph level off?

A

the reaction is finished and ALL of the (named reactant) has reacted

67
Q

why must the line of graph pass through origin?

A

because when there is no (named reactant) added, there is no reaction

68
Q

what happens when we add carbonate to acid

A

effervescence

69
Q

how is bunsen burner adjusted to give very hot flame

A

open collar

70
Q

disadvantage and advantage of using measuring cylinder compared to pipette

A

advantage: quick and easy to use
disadvantage: less accurate

71
Q

estimate pH of dilute sulfuric acid

72
Q

where does cold water enter the condenser

A

bottom jacket

73
Q

substances obtained from filtration

A

residue (solid)
filtrate (solution)

74
Q

another method instead of bung

A

divided flask with reagent tube inside, tipping it will start reaction

75
Q

observations when copper (II) sulfate is heated

A

white fumes, collect at mouth of test tube and copper (II) sulfate turns white

IGCSE Chemistry (12 decks)

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