chapter 1 - experimental chemistry.doc

8/10/2019 Chapter 1 - Experimental Chemistry.doc

1/5

Chap 1: EXPERIMENTAL CHEMISTRY

I). Measurements:

The study of chemistry requires the measurement of various quantities, such as mass and

volume.

Mass:

The mass of a substance is the amount of matter it contains. Its unit is thegram (g)for

small amounts or the kilogram (kg)for larger amounts. It is measured using a beam

balance or an electronic balance.

Fig 1.1. Beam Balance

Fig 1.2. Electronic balance.

Time:


2/5


3/5

Fig 1.-. ! measuring cylinder is accurate to the nearest cm.

Fig 1./. ! burette is accurate to the nearest '.1 cm. The volume of liquid required is runoff from the bottom through a ta".

Fig 1.0. ! "i"ette measures fied volumes 2-cm, -'cm, 1'cm, etc. very accurately.

II). C!!e"tin # $ases:

Spee% # Chemi"a! Rea"tins:In a chemical reaction #here a gas is given off, #e can

measure the s"eed of the reaction by recording the volume of gas given off in a certain

time interval, #hich can be measured using a gas syringe, or by recording the "rogressiveloss in mass as the gas esca"es into the air, #hich can be measured using a balance.

To collect a gas, the follo#ing "ro"erties may be ta$en into consideration*

1. Its density #ith res"ect to air.


4/5

2. its solubility in #ater

If the gas 3to be collected4 is denser than air, it can be collected using the do#n#ard

delivery method, in #hich the air is dis"laced u"#ard.

If the gas is lighter than air, it can be collected using the u"#ard deliver method, in #hich

the air is dis"laced do#n#ard, and the gas is collected in an u"side&do#n container.

For gases that are insoluble or slightly soluble in #ater, the method of dis"lacement of

#ater may be used, in #hich the gas is "assed through #ater into an u"side do#ncontainer5 the gas collects on to" and the #ater gets dis"laced do#n#ards.


5/5

chapter 1 - experimental chemistry.doc

Documents