+

Experimental Chemistry

Measurements in Chemistry

+Measurements in Chemistry

Four basic physical quantities measured in Chemistry experiments:

1. Volume

2. Temperature

3. Time

4. Mass

+Measurement: Volume of Liquids

The apparatus used depends on:– the volume being measured–how accurate the measurement needs to be

Common apparatus: Measuring cylinder Burette Pipette Beaker** Conical flask**

+Measurement: Volume of Liquids

Measuring cylinder Only used for measuring

approximate volume Accurate only to the

nearest 1 cm3

+Measurement: Volume of Liquids

Bulb pipette Measures out precise

volumes EXACTLY 20.0 cm3, 25.0

cm3 or 50.0 cm3

Used with a pipette filler

+Measurement: Volume of Liquids

Burette Long scale: 0 cm3 to 50 cm3

Each graduation is 0.1 cm3

Accurate up to 0.05 cm3

+Other Measurements

Physical quantity to be measured

Apparatus

volume of gases gas syringe Measures up to 100 cm3

temperature thermometer Accuracy to 0.5°Ctime digital

stopwatchMeasures to nearest second

mass of substance electronic balance

Measures to nearest 0.01 g

+Apparatus for Chemistry Experiments

Water bath: Heating flammable liquid

+Apparatus for Chemistry Experiments: Rates of reaction

Change in mass

+Apparatus for Chemistry Experiments: Rates of reaction

Collecting and measuring a volume of gas Conical flask VS test tube

+Collection of GasesMethods depends on the physical properties of the

gas the solubility of the gas in water the density of the gas compared to air

+Collection of Gases: Solubility & Density of Common Gases

Gas Solubility in water Density compared to air

ammonia extremely soluble less dense

carbon dioxide slightly soluble denser

chlorine soluble denser

hydrogen not soluble less dense

oxygen very slightly soluble slightly denser

sulfur dioxide very soluble denser

+Collection of Gases:Dry Samples

Dry samples can be obtained by passing the gas through a drying agent.

Common drying agents:

concentrated sulfuric acid [ ammonia]✗

quicklime (calcium oxide) [ ammonia]✓

Fused calcium chloride

+Concentrated Sulfuric acid

+Quicklime & Fused Calcium Chloride

+Data Logging