Chapter 1 SABIS Grade 10 (Level L) Chemistry

Chapter 1.1: Laboratory Skills Chemical Apparatus 

Chapter 1.1: Laboratory Skills Safety Rules 

Chemical Apparatus used in Chemistry Lab

Evaporating dish: Used in crystallization

 

Burette: To measure variable volumes of liquids from 0 to 50 ml to the nearest 0.05 cm³ per reading. Determining the V of liq used requires two readings to be taken and subtracting one from the other, therefore, the uncertainty per measured V is ±0.1 cm³ .

 

Pipette: To measure specific V of liq (exactly 5, 10, 25 or 50 cm³ ) with great accuracy, uncertainty of ∓0.05 cm³ 

. It has one calibration mark.

 

Measuring cylinder: To measure various volumes of liquids, accuracy depending on size and graduation of the cylinder (rather inaccurate) .

Volumetric flask: To prepare solutions with a specific volume, e.g. 250 cm³ , 1000 cm³ , etc., to the nearest 0.10 cm³ .

Separating funnel: To separate two immiscible liquids

Beaker: To measure only approximate volumes of liquids, not to be used for precise quantities. It can be also used as a container. 

Volumetric flask: Volumetric flask used to prepare solutions with a specific volume and to the nearest 0.10cm³ .

Separating funnel: used to separate two immiscible liquids.

Test tube holder: used to hold test tubes while heating them.

Wire Gauze: used to allow uniform heat distribution when using a Bunsen-burner.

Rules which should be followed when using a Bunsen burner.

Safety rules when using a Bunsen burner:

• Never open the gas tap before placing the lighted match near the muzzle of the burner.
• Never leave the Bunsen burner with a blue flame when not in use. A red flame is more easily seen than a faint blue flame. A blue flame is more likely to go off.

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Rules to be followed when heating a test-tube.

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. Crystallization: is the process of forming crystals.

 

Apparatus used in crystallization: Bunsen burner, tripod, wire gauze, beaker for the steam bath, evaporating dish, tongs 

 

Demonstration: steps to follow to perform a crystallization using salt and water.

 

There are two methods to be followed during crystallization using a non-flammable solvent. 

 

Use tongs and never your hands to transfer the hot evaporating dish to a steam bath.

 

 

Alcohol is a flammable volatile solvent. Heating it is never done by direct heating, but by using a steam bath or an electric heater.

 

Filtration the process of separating a liquid from an insoluble solid e.g sand and water.

 

 

Sugar and salt are soluble in water.

 

Sugar is soluble in alcohol salt is not.

 

Sand is insoluble in alcohol and water.

 

 

Filtration apparatus: beaker or conical flask, funnel, filter paper and filter stand.

 

Filter paper: porous paper used to separate insoluble solids from liquids or solutions.

 

Filtrate: The liquid that passes through the filter paper in the filtration process.

 

Residue: The solid which is left behind on the filter paper in the filtration process.

 

Demonstration: filtration to separate sand from water.

 

Common sizes of a pipette: 5, 10, 25 and 50ml.

 

Demonstration: Steps to follow while filling a pipette.

 

Demonstration: steps to follow to fill a burette.

 

Demonstration: steps to follow to measure a volume using the burette

 

A drop of liquid has a volume of 0.050 ml. 

 

From the most to least accurate apparatus: pipette, beaker, cylinder, and burette.