Ch1 Separation and Collection Flashcards
CREDITS TO GOOGLE for the stuff idk
1. How issit separated
- Fixed what?
- Cannot be a…?
Pure Substances Properties
- Cannot, separated, physical, means
- Fixed, boiling, point, fixed, density
- Cannot be a mixture
3 total, opposite of pure
Impure Substances Property
- Can, separate, physical, means
- boils/melts over range of temp, no fixed density
- Can be a mixture
The higher the Mr, the ____ the gas
denser
THINK ABOUT IT
As the relative mass increases, the density also increases
Solid-solid separation methods
- Magnetic separation
- Sublimation
- Filtration
decanting is solid liquid btw
Example of sublimeable solids
- Iodine
- Dry Ice
- Ammonium Chloride
- Naphthalene (moth balls)
ALL these are in solid state.
Liquid-solid separation methods
- Filtration
- Decanting
- Evaporation to dryness
- Crystallisation
Fractional Distillation usually liquid liquid!!
Liquid-liquid separation methods
- Circular Paper Chromatography
- Ascending Paper Chromatography
- Simple Distillation
- Fractional Distillation
- Separating Funnel
What is the Mr of air?
30
Solid ammonium chloride + solid X
separate solid X from ammonium chloride
Sublimation
sublimeable solids
- ammonium chloride (s)
- iodine (s)
- dry ice (s)
- Napthalene (s) (moth balls)
Huge Crystals with soln.
how to separate
Decanting
huge and numerous
powder X, heat-stable
Y, soluble in water
- add water, stir thoroughly until Y completely dissolve
- filter mixture
- retrieve, pour filtrate onto evaporating dish, evaporate to dryness
Gas syringe diagram
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit page 5
Solid Y not heat stable
Powder X, soluble in water
Crystallisation.
soluble but not heat-stable is the key here!
Wat is crystallisation?
Heating to, point of saturation
How does crystallisation work?
changing, solubility of solid with temperature
- temp increases -> solubility increases
- temp decreases -> solubility decreases, crystals formed
What happens to crystals in crystallisation when you overheat it? Why?
decomposes when heated
What is the point of saturation? How to check for saturation point?
What it is
Where biggest crystals, formed
How to check
Dip a cold, clean glass rod
Positive: Crystals form, glass rod
Negative: No crystals form, glass rod
For Chromatography, how do we see which solutes are of lowest solubility?
nearer to the ink dot = lower solubility
What must take note when making ascending paper chromatography?
- Solvent, below startline
- Startline drawn, graphite pencil
- high solvent front
- cannot let solvent front travel 2 edge of paper
- lid cover beaker, solvent
- Does a solute have different solubility in different solvents?
- Why cannot draw startline with pen?
- Yes
- Pen, soluble in water, affect chromatography results, graphite in pencil, insoluble in water
Rf Value Formula
Dist travelled by component/Dist between solvent front and starting line
3 Locating Agents + What are locating agents used for?
- Ninhydrin
- UV light
- Iodine
Detect, colourless, substances, on chromatogram
3 Uses of simple distillation
- Crude Oil Separation
- Distillation obtain alcohol, perfumes
How to increase efficiency of separation for FRACTIONAL DISTILLATION
longer fractionating column
longer fractionating column = better separation
What is the Water Bath for in Distillation?
What is it for?
prevent direct heating, if any flammable gases are in round bottomed flask, will not catch fire.
THINK ABOUT IT
Direct heating + flammable gases is some trouble, it will cause it to catch fire. Thats why its called “flammable” after all
Where is the water bath placed in distillation?
Around the round-bottomed flask
That is where the initial flask is (containing all the initial sol.)
Where is the thermometer put in distillation setup? Why?
Put at the mouth of the condenser
Why?
accurately measure the boiling point, of gas
What are boiling chips for?
ensure uniform heating
Where are boiling chips placed at?
inside the round-bottomed flask
How is the condenser placed in a distillation setup? Why?
placement
Water in bottom, water out top
why?
- Water go against gravity
- ensure cold water fillup as much space condenser
- maximize efficiency of condensation
I want to put a rubber stopper on the conical flask to maximize condensation. Can I? Why/Why not?
No.
Why Not?
buildup of pressure within the flask, cause explosion
Why will there be a buildup of pressure when the condenser condensed all the gas into liquid anyways?
Some gas may still escape the condenser and end up in the conical flask
I have oil and water. How to separate?
Using a separating funnel
What does miscible mean?
mix form homogenous solution
Example:
Petrol and water
3 gas dryers
Conc. sulfuric acid
Calcium chloride
Calcium oxide
What can calcium oxide dry?
Hydrogen and Ammonia gases
credits google lol i didn’t know it dry hydrogen
What can conc. sulfuric acid dry?
Acidic, neutral gases insoluble in water
What can calcium chloride dry?
anything except conc. sulfuric acid, calcium oxide dried gases
What apparatus to use to measure gas? How does the setup look like?
Gas syringe
TIP:
- gas syringe use conical flask
- water displacement use measuring cylinder
- downward, upward collection use test tube/gas jar
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit page 6
When to use downward upward collection/displacement of water + their diagrams
Downward Collection
- Mr > 30
Upward Collection
- Mr < 30
Displacement of water
- Mr too close, 30
- volume of gas, determined, measuring amt. of water displaced
DIAGRAMS
Downward collection
Upward collection
Displacement of water
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit PAGE 1
I wan collect Gas B that is soluble in water and Mr = 32 how do I do it?
Gas syringe
**(rarely will have this kinda qns with gas syringe as collection)
ethanol b.p.
78deg
78% nitrogen in inhaled, exhaled air, just saying…
sublimation vs decomposition
sublimation
- no chem. reaction
- change of state
decomposition
- chem. reaction
- new products
what causes vaporisation? what is it?
vaporisation: conversion, any substance from liquid -> gaseous state
is oxygen soluble in water?
no
is hydrogen, nitrogen soluble in water?
no
is carbon dioxide, ammonia gas soluble in water?
yes
does “fluid” consist of solid, liquid or gas?
liquid and/or gas
what 2 measure time
digital, mechanical stopwatch
wat 2 measure mass, and SI unit
electronic, beam balance
SI: kg
wat 2 measure volume, and SI unit
- gas syringe
- burette
- pipette
- volumetric flask
- measuring cylinder
SI: m^3
wat to measure temp. and SI unit
-
alcohol thermometer
SI unit: Kelvin
wat to measure length and SI unit
metre rule
SI unit: m
what does pipette and volumetric flask measure?
pipette: accurate fixed smaller volumes
volumetric flask: accurate fixed large volumes
Fill in the blanks
smaller particles pass through ___ of filter paper, while bigger particles are retained on it
pores
what is the liquid collected in conical flask after distillation called?
distillate
not filtrate
why use conical flask as recieving flask for distillation?
- narrow neck, reduce loss of distillate
1spot chromatogram vs no spot chromatogram
1spot:
pure substance
nospot:
insol. in solvent or
sample dissolved in solvent (if starting line below solvent)
from top to bottom, list components of paper chromatography.
- lid
- solvent front
- chomatography paper, chromatogram
- spot
- starting line, sample
- solvent
SETUP
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit page 2
why use small amt. of sample in paper chromatography?
prevent tailing, smudging of different components,
identify spots easily
why have high solvent front but cannot allow solvent front to travel to edge of paper
high solvent front
allow all components, separate fully
cannot allow solvent front travel -> edge
- prevents components, being unaccountable as it is more accurate measure actual distance travel by solvent
wat is lid on paper chromatography for?
prevent evaporation, solvent
wat is chromatography paper for paper chromatography for?
- allow separation, components in sample
why starting line above solvent?
- prevent sample, dissolve in solvent
advantages of using paper chromatography
- quick, accurate analysis of sample
- req small amt. of sample
- separate complex mixture
define solute
substance which dissolve in solvent, form soln.
define solvent, solvent front
solvent
liquid in which solute dissolve in
solvent front
frontmost area/end point, solvent travels to
3 scenarios where filter funnel used
- filtration
- precipitation reaction
- filter excess solid reactant
accuracy of apparatus
- burette
- pipette
- measuring cylinder
- Electronic Balance
- ANALOUGE Stopwatch
- DIGITAL Stopwatch
- ALCOHOL Thermometer
Burette: +- 0.05cm^3
Pipette: more accurate than measuring cylinder
Measuring Cylinder: +-0.5cm^3
Electronic Balance: +-0.01g
ANALOUGE Stopwatch: +- 0.1s
DIGITAL Stopwatch: +- 0.01s
ALCOHOL Thermometer: +-0.5deg celc
How 2 accurately read volume of liquid?
Read off scale:
1. eye lvl
2. meniscus, liquid
CONCAVE VS CONVEX MENISCUS READING
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit Page 3
Common liquids that have concave, convex mensicus
CONCAVE
water
CONVEX
mercury
what is a meniscus?
surface of liquid, curves at sides of walls, measuring instrument
gas drying diagram
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit page 7
Long tube in first.
gas diffusion diagram
- hydrogen outside
- air inside
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit page 8
water displacement can collect o2?
yes
