mount of substance?","back":"

The quantity that counts the number of chemical particles present.
Symbol: $n$.
Unit: mole (mol).

","points":2,"mcqOptions":[{"text":"

The quantity that counts the number of chemical particles present.
Symbol: $n$.
Unit: mole (mol).

","correct":true,"explanation":"Amount of substance measures how many specified chemical particles are present, expressed in moles. Its symbol is $n$, and one mole contains the Avogadro constant of particles."},{"text":"

The total mass of the chemical particles present.
Symbol: $m$.
Unit: gram (g).

","correct":false,"explanation":"This confuses amount of substance with mass, which measures the quantity of matter in grams. Amount of substance counts chemical particles indirectly and has symbol $n$ and unit mole."},{"text":"

The amount of chemical particles per unit volume.
Symbol: $c$.
Unit: moles per cubic decimetre (mol dm$^{-3}$).

","correct":false,"explanation":"This defines amount concentration, not amount of substance. Amount of substance represents the number of chemical particles present, has symbol $n$, and is measured in moles."},{"text":"

The mass of one mole of chemical particles.
Symbol: $M$.
Unit: grams per mole (g mol$^{-1}$).

","correct":false,"explanation":"This defines molar mass, which relates mass to one mole of particles. Amount of substance instead counts the particles present and is represented by $n$ in moles."}]},{"id":"40c13a2c-b04c-4833-b9dd-2ecddc64b37c","cardType":"basic","front":"What is a formula unit?","back":"The simplest whole-number ratio represented by an ionic formula.","points":1,"mcqOptions":[{"text":"The simplest whole-number ratio represented by an ionic formula.","correct":true,"explanation":"An ionic compound forms a giant lattice rather than discrete molecules, so its formula unit gives the simplest whole-number ratio of its constituent ions."},{"text":"The actual number of atoms present in a single ionic molecule.","correct":false,"explanation":"This incorrectly treats an ionic compound as consisting of discrete molecules. A formula unit instead states the simplest whole-number ratio of ions in the ionic lattice."},{"text":"The simplest whole-number ratio represented by a molecular formula.","correct":false,"explanation":"This confuses a formula unit with an empirical formula. A formula unit specifically gives the simplest whole-number ratio of ions represented by an ionic formula."},{"text":"The relative mass of one mole represented by an ionic formula.","correct":false,"explanation":"This confuses formula units with molar mass, which is the mass per mole of a substance. A formula unit gives the simplest whole-number ratio of ions."}]}]}],"examCountdown":{"examDate":"2027-05-28","paperLabel":"Paper 1"},"heading":"The mole and the Avogadro constant","title":"The mole and the Avogadro constant Flashcards","topicSidebar":"$L40"}]}],"topicId":"5f9b0e45-40cf-5f93-baea-a4f5e62e210d","walled":"$L41"}],"$L42"]