C2

Accuracy in experimental work in the laboratory

Ensuring precise and reliable results in scientific experiments.

Apparatus used for measurement in chemistry

Instruments and tools utilized for measuring quantities in chemical experiments.

Rates of reactions

The speed at which chemical reactions occur.

Instrument

accurate stopwatch (hundredth of second):A precise timing device used to measure short durations of time in hundredths of a second.

Unit of time

hours (h), minutes (min), seconds (s):Standard units of measuring time in scientific experiments.

Instrument

thermometer:A device used to measure temperature.

Alcohol-in-glass

A type of thermometer that uses alcohol as the liquid inside the glass tube.

Mercury-in-glass

A type of thermometer that uses mercury as the liquid inside the glass tube.

Dangerous if it breaks

The potential hazards associated with the breakage of a mercury-in-glass thermometer due to the toxicity of mercury.

Unit

degrees Celsius:The unit of measurement for temperature in the Celsius scale.

Accuracy

tenth of a degree:The level of precision in temperature measurement, accurate to one-tenth of a degree.

Read

eye level of meniscus -> no parallax effects:Reading the temperature by aligning the eye level with the curve of the liquid (meniscus) in the thermometer, avoiding parallax errors.

Meniscus

The curved shape formed by the liquid surface in a container due to surface tension.

Mass

The amount of matter in an object.

Instrument

electronic balance:A device used to measure the mass of an object electronically.

Unit

grams (g) or kilograms (kg):Standard units of measuring mass in scientific experiments.

Accuracy

hundredth of a gram:The level of precision in mass measurement, accurate to one-hundredth of a gram.

Read

wait until reading = steady on balance:Allowing the reading on the electronic balance to stabilize before recording the mass of an object.

Volume

The amount of space occupied by a substance or object.

Liquid

amount of space it takes up:The volume occupied by a liquid substance.

Units

liters (l), cubic centimeters (cm³), or milliliters (ml):Standard units of measuring volume in scientific experiments.

1 liter = 1000 cm³

The conversion factor between liters and cubic centimeters.

1 cm³ = 1 ml

The equivalence between cubic centimeters and milliliters.

Read

apparatus needs to be vertical & on eye level with top of meniscus:Ensuring the apparatus used for measuring liquid volume is positioned vertically and the eye level is aligned with the top of the meniscus for accurate readings.

Criteria for purity

Standards and requirements for determining the level of purity in substances.

Drugs = high purity degree

Drugs need to have a high degree of purity.

Ensured by dissolving in suitable solvent + subjected to fractional crystallization

Achieving high purity in drugs by dissolving them in an appropriate solvent and subjecting them to fractional crystallization.

Chemical, pharmaceutical & food industry

substances must be pure:Industries such as chemical, pharmaceutical, and food require substances to be pure for various reasons.

Impurities affect chemical, physical & biological behavior

The presence of impurities can alter the chemical, physical, and biological properties and behavior of substances.

Testing purity

Evaluating the level of purity in a substance.

Melting point

The temperature at which a substance changes from a solid to a liquid state.

Pure = sharp melting point

A pure substance exhibits a distinct and precise melting point.

Impure

melting happens at a range of temperatures:An impure substance has a melting point that occurs over a range of temperatures.

Boiling point

The temperature at which a substance changes from a liquid to a gas state.

Pure

temperature = steady at boiling point:A pure substance maintains a constant temperature at its boiling point.

Impure

boil at a range of temperatures:An impure substance boils over a range of temperatures.

Chromatography

A technique used to separate and analyze the components of a mixture based on their differential movement through a stationary phase and a mobile phase.

Pure

produce 1 well-defined spot on chromatogram:A pure substance results in a single, clearly defined spot on a chromatogram.

Impure

several spots:An impure substance produces multiple spots on a chromatogram.

Solubility

The ability of a substance to dissolve in a solvent at a specific temperature.

Pure

all substance dissolves in suitable solvent at perfect temperature:A pure substance completely dissolves in a suitable solvent