Unit 12 Experimental Techniques Partial

How to measure the time

Stopwatch

How to measure temperature ?

Thermometer

How to measure mass

Digital Balance

How to measure approximate volumes of a liquid

Measuring Cylinder

How to accurately measure a fixed volume of liquid

Volumetric Pipette

How to accurately measure a variable volume of liquid

Burrettes

How to measure volume of Gas precisely and accurately

Gas Syringe

Disadvantage of Gas Syringe

Limited volume

Expensive

Fragile

Solvent

Substance that dissolves a solute

Solute

Substance that is dissolved in a solvent

Solution

Mixture of one or more solutes dissolved in a solvent

Saturated Solution

Solution containing the maximum concentration of a solute dissolved in the solvent at a specific temperature

Residue

Substance that remains after evaporation, distillation, filtration or any other substance

Filtrate

Liquid or solution that has passed through a filter

Chromotography process

Pencil line is drawn on chromatography paper and spots of the sample are placed on it

Paper is lowered into to the solvent container, ,making sure the pencil line sits above the level of the solvent so the samples don’t was into solvent container

Solvents travel up the paper taking some of the substance with it, different substances have different so they will travel at different rates causing them to spread apart#

Substance with higher solubility will travel farther

Substances with the same solubility will be

The same substance

Substances with multiple substances will have

produce more than one spot

Locating Agent

Used to see spots which aren’t visible with the human eye

Rf

Distance travelled by substance/ Distance travelled by solvent

How to identify carbon dioxide?

Using limewater, turns cloudy

How to test for chlorine

Bleaches damp litmus paper

How to test for hydrogen

Squeaky pop of lighted splint

How to test for oxygen

Glowing splint goes out than relights

How to test if substance is pure or impure

Fixed boiling/ melting points if pure, range of temperatures if not

How to use a suitable solvent to separate

Solids with different solubility, one dissolves in solvent other doesn’t

Place both in solvent

One will dissolve other won’t

How to use Filtration for separation

Used on mixture containing a insoluble solid in a liquid or solution

Filter paper placed in funnel above another beaker

Mixture powered placed in filter funnel above beaker

Filter paper will only let small liquid particles through into the filtrate

Solid particles will be too large too pass and stay behind as residue

Crystillisation

Dissolved solid from a solution

Solution heated allowing solvent to evaporate and leave a saturated solution behind

Dip clean dry cold rod into solution, crystals should begin to form when removed and allowed to cool

Saturated solution is allowed to cool

Solid will come out the solution as solubility decreases, crystals growing

Crystals collected by filtration

Washed with distilled water to purify, then allowed to dry

Simple Distillation

Liquid and soluble solid from a solution

Solution is heated, and the substance with the lower boiling point evaporates and boils producing a vapour which rises through the neck of the round bottom flask

Vapour passes through the condenser where it condenses and turns into pure water collected in a beaker

Only solid solute left

Fractional Distillation is used instead of simple distillation when

The liquids have a closer boiling point or a greater degree of accuracy is needed

Fractional Distillation

Used for miscible liquids

Substance raised to the boiling point of the substance with the lower boiling point

This substance will evaporate first

Rise and pass through fractionating column

Passes through condenser where they will cool and condense

Condensed liquid is collected in beaker

All of the substance is evaporated and collected