01. Experimental Chemistry

Like all science chemistry involves measurements of various quantities. Often in chemistry we need accurate measurements of chemicals, solids(like crystals and powder), liquids(acid and alkali)or gases. To measure these different values we have different quantities, for solids we have mass, for liquids and gases we have volume.     

The Mass

The mass of a substance is regarded as the amount of matter it consists of. The SI unit for mass is "grams(g) " for small amounts and kilograms(kg) for larger amounts.

The apparatus used in school laboratory to measure mass is called a beam balance. In a beam balance, a weight is moved along a horizontal scale until it balances the mass of an object on the scale pan. Electric beam balance can measure masses even more accurately to 0.01g or even 0.001g.

The Volume

The volume of a substance is the amount of space it occupies. The SI unit for volume is "cubic centimeters(cm³)" for larger values "cubic decimeter(dm³)" is used. Liquids are measured using graduated beakers, for example measuring cylinder, pipette, burette. Volumetric flask is used to, both measure fixed volume of liquid and is used for preparing solution of known concentration.

                                      The common laboratory instrument for measuring volume.

When we measure the volume of a liquid, it is important to read the bottom of the curve surface of the liquid, called the Meniscus, in the center. Syringe can also be used to measure volumes of gases and liquids.

                                    

Time and Temperature

Time is a very important quantity in the laboratory. The SI unit for time is "seconds(s)". We can use a stopwatch to measure time accurately up to 0.01s{human reaction time fyi not important}.    

Temperature is also as important . The SI unit for temperature is "degree Celsius(^oc)". We use a thermometer to measure temperature in the lab.

    

What to measure	Units	Measuring device
Mass	Milligram (mg) Gram (g) Kilogram (kg) 1 000 mg = 1 g 1000 g = 1 kg 1000 kg = 1 tonne	-Beam balance -Electronic balance
Volume	Cubic centimeters (cm3) 1 000 cm3 = 1 dm3 1 dm3 = 1 litre 1 000 dm3 = 1 m3	-Beaker -Measuring cylinder   -Pipette -Burette -Volumetric flask -Syringes
Time	Second (s) 60 s = 1 min 3600 s = 1 h	-Stopwatch -Stopclock
Temperature	Degree Celsius (Co)	-Mercury-in-glass thermometer -Electronic thermometer