How do chemists actually identify unknown substances or measure exact concentrations? This deck of 20 flashcards covers the core analytical techniques used in every chemistry lab, from titration and chromatography through to spectroscopy and mass spectrometry....
How do chemists actually identify unknown substances or measure exact concentrations? This deck of 20 flashcards covers the core analytical techniques used in every chemistry lab, from titration and chromatography through to spectroscopy and mass spectrometry. You'll learn how titration determines unknown concentrations using equivalence points and indicators, how chromatography separates mixtures using Rf values and stationary/mobile phases, and how UV-Vis spectroscopy uses the Beer-Lambert law to measure concentration from absorbance. The deck also introduces infrared spectroscopy for identifying functional groups, mass spectrometry for determining molecular mass, and NMR spectroscopy for structural analysis, finishing with the difference between precision and accuracy and systematic versus random error. Suited to A-Level and AP Chemistry students preparing for practical exam questions, these flashcards connect each technique to what it's actually used to find out.
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Determining the unknown concentration of a solution by reacting it with a solution of known concentration until the reaction reaches its endpoint.
The point at which the moles of titrant added exactly react with the moles of the substance being analysed.
A substance that changes colour near the equivalence point, signalling the endpoint of the titration visually.
Phenolphthalein: colourless in acidic solution, pink in basic solution (changes around pH 8.2โ10).
Separating a mixture into its individual components based on differing rates of movement through a stationary phase, carried by a mobile phase.
The retention factor: the ratio of the distance travelled by a compound to the distance travelled by the solvent front.
The stationary phase stays fixed (paper, silica gel); the mobile phase moves through it, carrying dissolved components at different rates.
Separating and analysing volatile compounds based on their interaction with a stationary phase inside a column, as they're carried by an inert gas.
The study of how matter interacts with electromagnetic radiation, used to identify substances and determine structure or concentration.
Absorption of ultraviolet and visible light by a sample, often used to determine concentration via the Beer-Lambert law.
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Characteristic vibrations of specific chemical bonds, used to identify functional groups present in a molecule.
The mass-to-charge ratio of ionised particles, used to determine molecular mass and structural fragmentation patterns.
The peak with the highest mass-to-charge ratio, corresponding to the unfragmented molecule that has lost one electron.
Nuclear Magnetic Resonance spectroscopy determines the structure of organic molecules by detecting the magnetic environment of specific nuclei (commonly ยนH and ยนยณC).
A graph relating a known property (e.g. concentration) to an instrument's measured signal (e.g. absorbance), used to determine unknown sample values.
Qualitative analysis identifies what substances are present; quantitative analysis determines how much of each substance is present.
A reference sample containing everything except the analyte, used to zero the instrument and correct for background absorbance.
Precision refers to the reproducibility of repeated measurements; accuracy refers to how close a measurement is to the true value.
A systematic error consistently skews results in one direction (e.g. miscalibrated instrument); a random error causes unpredictable variation in either direction.
