P6 Flashcards
1
Q
Filtration
A
used to separate insoluble solid from water or sol
2
Q
Define solvent
A
liquid that dissolve the solute
3
Q
simple distillation
A
used to obtain the solvent from aqueous sol
1-Heat the mixture
2-condense the vapour
4
Q
Define solute
A
solid dissolved by the solvent
5
Q
Evaporation
A
used to obtain the solute from ad sol
to obtain powder: evaporate till dryness
to obtain crystals: undergo crystalization
6
Q
Describe the effect of boiling a colored sol for several hours
A
the color will get darker
7
Q
why heating app a will cause the tube to crack
A
it will crack due to increased pressure as there is no side arm
8
Q
How to undergo crystallization
A
heat till point of crystallization
how to know crystallization point?
1-get a glass rod and dip it into the sol then place it on cold surface crystals will form
2-cool
3-filter
4-wash
5-dry between 2 filter papers
9
Q
why is it better to place the thermometer bulb above the vapor as in B not in the liquid as in A
A
to measure the temp of the vapor as the temp of liquid would not be constant
10
Q
Separating funnel
A
used to separate immiscible liquid
Examples
oil water
petroleum and water
11
Q
fractional distillation
A
used to separate mixture of liquids with diff boiling points
Examples
nitrogen and oxygen from air
ethanol and water
12
Q
which liquid will collect first
A
the one with lower bp
13
Q
how will the student know when all the liquid is collected
A
when the reading on thermometer start to increase again
14
Q
why electric heater is used instead of Bunsen burner when heating ethanol
A
as ethanol is flammable
15
Q
chromatography
A
used to separate mixture of colored dyes and amino acids and glucose
16
Q
name a suitable solvent
A
water or ethanol
17
Q
why draw a line in pencil
A
as it is insoluble so will not interfere with results
18
Q
why the baseline should be above the level of solvent
A
the dyes will dissolve down in the solvent
19
Q
why a glass cover is used
A
to prevent evaporation of solvent
20
Q
when should the paper be removed from the solvent
A
when the solvent is near the top of paper
21
Q
what is used to apply the mixture into the paper
A
teat pipette
22
Q
A student investigated the green colour in grass
the student followed these instructions
1-cut the grass into small pieces and crush the grass by grinding with sand and ethanol
2-decant the liquid
3-investigate which colors are present in the green solution
A
outline how student could carry out instruction 3
-draw a baseline with a pencil on the filter paper
-place the filter paper in a beaker containing the solvent (ethanol)
-place a drop the green solution using a pipette
-the baseline should be above the level of ethanol
-wait until it reach the solvent front
-the no of spots for it equal to the no of colours present
23
Q
calcium burns in air to form calcium oxide. The reaction is vigorous and some of the calcium oxide can be lost as smoke. Plan investigation to determine the maximum mass of oxygen burnt in air
A
-measure 2g of Ca using a balance
-crush the 2g Ca in mortar and pestle
-transfer 2g of Ca into a crucible,heat,cover,with alid
-remove the lid occasionally to allow O2 in
-repeat heating,cooling,weight until the lass gets constant
-final mass of CaO - initial mass of Ca
24
Q
Potassium sulfate is the salt produced when sulfuric acid is neutralised by potassium hydroxide solution.
The correct amount of potassium hydroxide solution must be added to neutralise all of the
sulfuric acid. Plan an experiment to obtain pure crystals of potassium sulfate from sulfuric acid and
potassium hydroxide solution. You are provided with common laboratory apparatus.
A
-add 25cm of KOH into a cornical flask using a pipette
-add 3-5 drops of methyl orange using dropper
-fill the burette; with the zero make. With H2SOF4
-add H2SO4 acid slowly into the cornical flask until the indicator changes colour
-repeat 3 times and take average
-repeat without using indicator. But using the same noted amounts acid and alkali
-crystallization in details
25
Agri Limes are mixtures of calcium carbonate and calcium oxide. Farmers use Agri Limes on fields
to neutralise acidity.
Plan an investigation to find out which of two different Agri Limes, Q or R, will neutralise more acid.
You are provided with common laboratory apparatus and chemicals, including dilute nitric acid.
-add 2g of agrilime Q into a cornical flask,measured using a balance.
-add 3-5 drops of methyl orange
-fill the burette with nitric acid till the zero mark
-add HNO3 slowly from the burette (while swriling the flask until the indicator changes colour)
-repeat the exp using agrilime R but using the indicator same mass conc of acid
the stronger the base,the greater volume
26
When solid barium hydroxide is added to solid ammonium chloride a reaction takes place.
(a) Describe an experiment to show that this reaction is endothermic.
(b) How could you show whether or not the final mixture contains ammonium ions?
measure initial temperature of (solid) ammonium chloride / barium hydroxide
add barium hydroxide / ammonium chloride /other solid AND mix / stir
use a thermometer
measure the temperature of the mixture / final temperature
temperature decreases /test-tube feels cold
add (aqueous) sodium hydroxide (and warm) 1
gas produced turns (red) litmus blue
27
Iron, tin and zinc all react with dilute hydrochloric acid to produce hydrogen.
Plan an experiment to determine the order of reactivity of iron, tin and zinc.
You are provided with powdered samples of the metals and common laboratory apparatus
-measure 2g of powdered iron
-add to 10 ml of hcl
-stopper the flask,conncet to gas syringe
-measure the volume of gas produced per unit time
-repeat the same exp but using same volume and conc of hcl,same mass and S.A of metal
-the greater the volume of gas produced, the more reactive metal
28
Potassium chloride is a salt that dissolves in water.
The solubility of a salt is the mass in grams of the salt that dissolves in 100 cm3
of water at a
particular temperature.
Plan an investigation to determine the solubility of potassium chloride in water at 40 °C.
You are provided with potassium chloride and common laboratory apparatus.
-measure initial mass of excess KCl.50g using a balance
-measure 100 cm3 of water using measuring cylinder add to beaker
-immerse the beaker in a water bath, adjusted to 40°C
-add solid to the water using spatula, stir using a glass rod.
-stop stirring when no more solid dissolves
-filter excess solid
-dry between 2 filter papers
-measure final mass of solid
-solubility (initial mass-final mass)
29
Propanone and ethyl ethanoate are both solvents which can be used to remove paint.
Plan an investigation to determine which of these two solvents is better to use to remove paint.
You are provided with glass slides, paint, the two solvents and common laboratory apparatus
-add two spots of paint on a glass slide, some size, same amount of paint
-leave to dry
-add equal no of drops on each slide 2-3 drops
-wipe the solvent and paint out using a cloth
-the less spot left out, the better the solvent
-repeat 3 times and take average
30
When iron nails rust, the mass of the nails increases.
Plan an experiment to investigate if iron nails rust more quickly in tap water or in distilled water.
You are provided with new iron nails and common laboratory apparatus.
M1 weigh specified number of nail(s) / specified number of nails
M2 immerse in same volume
M3 samples of tap water and distilled water (in two test-tubes)
M4 for suitable time
M5 dry (in oven)
M6 reweigh nails
conclusion; the greater the final mass the faster the rate of rusting
31
Fizzy drinks contain carbon dioxide gas dissolved in a liquid. The carbon dioxide gas can be
removed from the fizzy drink by heating.
Plan an investigation to find the volume of carbon dioxide gas in 1dm3 of a fizzy drink.
Include in your answer how you will calculate the volume of carbon dioxide gas dissolved in 1dm3
of a fizzy drink.
You are provided with a small sample (less than 1dm3
) of the fizzy drink and common laboratory
apparatus.
(1dm3 = 1000cm3)
known/specified volume of fizzy drink
* warmed/heated
* in a suitable container
* gas collected in inverted measuring cylinder over water or in a (gas) syringe
* until no more gas collected / all carbon dioxide given off / no more bubbles
32
A sample of muddy river water contains water, dissolved solids and insoluble solid mud. Plan an investigation to find the concentration of dissolved solids, in g/dm3 in the river water. In your answer state how you will work out the concentration of the dissolved solids in g/dm3
You are provided with a small sample (less than 1dm3
) of muddy river water and common laboratory
apparatus.
(1dm3= 1000
-measure initial volume of sol, using large measuring cylinder/1000
-filter the solution to remove the mud.
-transfer the filtrate to round bottom flask. And measure the initial mass.
-heat the solution till dryness repeat heating,cooling,weight until constant mass
-measure final mass
-mass of salt=initial mass-final mass
33
Caffeine occurs naturally in coffee beans. Caffeine is a white crystalline solid. It is very soluble in
hot water but much less soluble in cold water.
Plan an investigation to obtain a pure crystalline sample of caffeine from coffee beans.
Assume that all other soluble substances in coffee beans are very soluble in both hot and cold
water.
You are provided with coffee beans and common laboratory apparatus
grind / crush / powder coffee beans
using pestle / mortar
add water and stir / mix
heat / hot (water) (to dissolve)
filter
leave (filtrate) to cool or leave to form crystals
wash / rinse (crystals / residue / caffeine
34
When solution A and solution B are mixed they react slowly to form iodine.
Starch solution is added to the mixture to act as an indicator.
When a certain amount of iodine is made there is a sudden colour change to blue-black.
Plan an investigation to find the effect of temperature on the rate of the reaction between solution A
and solution B.
You are provided with solution A, solution B, starch solution and common laboratory apparatus.
known volumes of aqueous solution A and solution B
suitable apparatus for measuring volumes of solutions
measure temperature
mix solutions together (with starch solution)
time until blue black colour seen
repeat at a different temperature
solutions warmed before they are mixed.
35
The leaves of some trees contain coloured substances which can be used as pH indicators. These
coloured substances are soluble in ethanol but insoluble in water.
You should assume that nothing else in the leaves is soluble in ethanol.
Plan an investigation to extract the coloured substances from some leaves and test them to see if
they work as a pH indicator.
You are provided with leaves from a tree and common laboratory apparatus and chemicals.
MP1 crush / grind leaves
MP2 using pestle / mortar
MP3 add ethanol to (ground up) leaves and stir / mix
MP4 filter (and split sample into two)
MP5 add named acid to one portion
MP6 add named alkali to second portion
MP7 samples colour will change / look for colour change
36
Old concrete contains calcium carbonate. Calcium carbonate reacts with dilute hydrochloric acid.
CaCO3(s) + 2HCl(aq) → CaCl 2(aq) + H2O(l) + CO2(g)
Plan an investigation to find which of two lumps of concrete contains the larger percentage of
calcium carbonate. Your plan should include how you will use your results to determine which one
of the two lumps has the larger percentage of calcium carbonate.
You have access to all common laboratory materials and a supply of dilute hydrochloric acid.
-measure 25 cm3 of HCl to a cornical flask
-measure 5g concrete (initial mass of mass of sample of concrete)
-crush and grind the solid using mortar and pestle
-add the HCl,heat gently and stir. Stop stirring when no more bubbles evolve
-
-filter the unreacted solid, wash with distilled water and dry between 2 filter papers.
-repeat the exp with other sample of CaCO3
37
Dilute hydrochloric acid reacts with calcium carbonate to make carbon dioxide gas. The apparatus
shown in the diagram can be used to follow the progress of the reaction. The carbon dioxide gas
leaves the flask causing the mass shown on the balance to decrease
Plan an investigation, using the apparatus shown in the diagram, to find out how the temperature
of the dilute hydrochloric acid affects the rate of the reaction. Your plan should include how your
results will show how the temperature of the dilute hydrochloric acid affects the rate of the reaction.
You are provided with dilute hydrochloric acid, calcium carbonate and common laboratory apparatus.
stated / set / same / measured volume of acid
* stated / set / same / measured mass of calcium carbonate
* add / combine / put together and start timing
* Repeat (with acid) at higher / lower temperature
then:
* graphical method:
* measure / record mass at known / regular / specified times
* plot graph
* steepest line is fastest
38
the energy given out when different liquid alcohols are burned can be compared using the apparatus
shown.
Describe how the apparatus shown can be used to compare the amount of energy given out by
three different liquid alcohols, ethanol, propanol and butanol. Your answer should include how the
results can be used to determine which fuel gives out the most energy.
any 6 from:
* specified / set volume / mass of water
* measure start temperature of water
* heat water using sprit burner for all three fuels
and
* start timing when heating started
* heat to set temperature / set temperature rise
* record time
* shortest time gives out most energy
OR
* measure mass of fuel (plus spirit burner) at start
* heat to set temperature / set temperature rise
* measure mass of fuel (plus sprit burner) at end (and subtract from first mass to fine mass of fuel used)
* smallest mass used gives out most energy
OR
* put specified mass / volume of fuel in spirit burner
* burn until burner goes out
* measure final temperature of water and calculate temperature rise
* highest temperature (rise) gives out most energy
OR
* heat water for a specified time
* measure final temp of water
* calculate temperature rise
* highest temperature (rise) is fuel that gives out most energy
38
Stayclean and Brightwhite are two brands of washing powder. Both contain sodium carbonate.
Sodium carbonate is soluble in water and reacts with dilute sulfuric acid to produce
carbon dioxide gas.
Plan an investigation to determine which of the two washing powders, Stayclean or Brightwhite,
contains the greatest percentage of sodium carbonate.
You are provided with samples of the two washing powders and common laboratory apparatus and
chemicals
gas volume method
* weigh both washing powders or equal masses of both washing powders
* place in suitable container (flask / boiling tube / test-tube)
* add acid
* to excess / until no more fizzing
* collect gas
* in gas syringe or by downward displacement in measuring cylinder
* measure volume of gas
* largest volume of gas has most sodium carbonate
OR
mass loss method
* weigh both washing powders or equal masses of both washing powders
* place in suitable container (flask / boiling tube / test-tube / beaker)
* add acid
* to excess / until no more fizzing
* weigh mixture once acid added
* weigh mixture at end
* calculate mass drop
* largest mass drop has most sodium carbonate
39
Cobalt, manganese and nickel are metals. They react with dilute hydrochloric acid to form
hydrogen gas.
Plan an investigation to find the order of reactivity of these three metals.
You are provided with:
● samples of each metal
● dilute hydrochloric acid
● common laboratory apparatus.
Your plan must make it clear how your investigation will be a fair test and how you will use your
results to place the metals in order of reactivity
add metals to HCl in a beaker / flask / test-tube
fair test – max 4
* same volume HCl
* some concentration HCl
* same temperature acid
* same mass / moles / amount metals
* same surface area / form of metal
measure
* start timing when solid added
* stop timing when all solid gone / reaction to stop
OR
* start timing when solid added
* stop timing when collected set volume of gas
OR
* start timing when solid added
* measure volume of gas after a set time
OR
* measure temperature at start
* measure temperature after reaction OR highest temperature reached
conclusion
* shortest time is most reactive
OR
* biggest volume of gas most reactive
OR
* biggest temperature change most reactive
40
The rate of reaction between magnesium and dilute hydrochloric acid can be followed by measuring
the volume of hydrogen produced.
Plan an experiment to investigate the effect of decreasing the temperature on the rate of this
reaction by measuring the volume of hydrogen produced.
You are provided with magnesium ribbon, dilute hydrochloric acid and common laboratory
apparatus.
Weighed amount / x gram of magnesium
* Add known volume of dilute hydrochloric acid
* gas syringe / measuring cylinder over water
* Use of stop-clock / timer
* Measure volume of hydrogen at fixed time or time for a fixed volume to be made
* Repeat using different temperatures
* Compare results / conclusion
41
Steel nails rust in the presence of air and water. Plan an investigation to:
● show that coating steel nails with paint helps to protect the nails from rusting
● show that coating steel nails with zinc helps to protect the nails from rusting
● determine which coating is more effective at protecting steel nails from rusting.
You are provided with:
● uncoated steel nails
● steel nails coated with paint
● steel nails coated with zinc
● common laboratory apparatus.
* weigh nails / use set number of nails
* place nails in a suitable container
* add water to nails
* leave in water for a suitable time (
≥ 1 week)
* observe nails / compare / reweigh nails
* repeat with nail with other coverings
* nail with least rust / mass increase has best coating
42
Magnesium reacts with dilute sulfuric acid at room temperature to form hydrogen gas.
Plan an experiment to find the rate of reaction between magnesium ribbon and dilute sulfuric acid.
In your answer:
● include a diagram
● indicate how you could use the results obtained to find the rate of reaction.
You are provided with common laboratory apparatus, magnesium ribbon and dilute sulfuric acid.
gas volume mass loss
M1 Mg added to sulfuric acid
M2 in a suitable container with ability to have a bung
M3 methods of measuring gas volume (gas syringe,
downward displacement of water using a measuring cylinder)
M4 start timer / timing (when added together)
M5 measure volume of gas
M6 at set time / at end of experiment / at (regular)
known intervals
M7 rate = volume ÷ time
42
Azurite is an ore of copper which contains copper(II) carbonate. Azurite contains no other metal
ions.
Plan an experiment to show how a sample of copper could be obtained from large lumps of azurite.
Your answer should include:
● descriptions of the reactions involved
● the expected observations.
You are provided with a large lump of azurite and common laboratory chemicals and apparatus
crush/powder azurite/ore/lumps
using a suitable method e.g. mortar and/or pestle, hammer
heat
in crucible / test-tube / boiling tube / etc
with carbon/coke /iron/zinc/
aluminium/magnesium/CO/
hydrogen
REDOX
brown solid formed
43
Iodine dissolves in two different solvents: ethanol and hexane.
Plan an experiment to find out in which solvent iodine is the most soluble at room temperature.
You are provided with iodine, the two solvents and common laboratory apparatus.
known volume of ethanol
* add known mass of iodine
* stir / shake
* filter
* dry and weigh (undissolved) iodine
* repeat with hexane
* the greater the dissolved amount the greater the solubility
44
nickel sulfate-6-water,NiSO4.6H2O is blue crystalline salt
plan an exp to obtain a sample of pure water from this salt, your answer should include a diagram of the apparatus, any expected observations and a test to show the presence pf pure water.
-add NiSO4.6H2O in the round bottom flask then heat
-water evaporates, then condenses in the condense and collected Vas pure water
-measure the B.p, water boils at exactly 100)C
