Use​ ​of​ ​amount​ ​of​ ​substance​ ​in​ ​relation​ ​to​ ​masses​ ​of pure​ ​substances

what is one mole of any substances

an amount of that substance that contains an Avogrado number of particles

the particles could be atoms, molecules, ions or electrons

Avogadro’s constant

6\.02 x 10²³*Using*​ ​*moles*​ ​*to*​ ​*balance*​ ​*equations*

using moles to balance equations

**Balancing**​ ​**numbers**​ ​**in**​ ​**a**​ ​**symbol**​ ​**equation**​ ​**can**​ ​**be**​ ​**calculated**​ ​**from**​ ​**the**​ ​**masses**​ ​**of reactants**​ ​**and**​ ​**products:**


1. **convert​ ​the​ ​masses​ ​in​ ​grams​ ​to​ ​amounts​ ​in​ ​moles**
2. **convert​ ​the​ ​numbers​ ​of​ ​moles​ ​to​ ​simple​ ​whole​ ​number​ ​ratios,​ ​then​ ​you know​ ​how​ ​many​ ​moles​ ​you​ ​have​ ​of​ ​one​ ​element/compound​ ​compared to​ ​another**

**total**​ ​**moles**​ ​**of**​ ​**one**​ ​**element**​ ​**must**​ ​**be**​ ​**the**​ ​**same**​ ​**on**​ ​**both**​ ​**sides**​ ​**of**​ ​**the**​ ​**equation**

*Limiting*​ ​*reactants*

 ==**limiting**​ ​**reactant:**​ ​**the**​ ​**reactant**​ ​**that**​ ​**is**​ ​**used**​ ​**up**​ ​**/**​ ​**not**​ ​**in**​ ​**excess**​ ​**(since**​ ​**it**​ ​**limits**​ ​**the amount**​ ​**of**​ ​**products)**==

* **In**​ ​**a**​ ​**chemical**​ ​**reaction**​ ​**with**​ ​**2**​ ​**reactants**​ ​**you**​ ​**will**​ ​**often**​ ​**use**​ ​**one**​ ​**in**​ ​**excess**​ ​**to ensure**​ ​**that**​ ​**all**​ ​**of**​ ​**the**​ ​**other**​ ​**reactant**​ ​**is**​ ​**used**
* **If**​ ​**a**​ ​**limiting**​ ​**reactant**​ ​**is**​ ​**used,**​ ​**the**​ ​**amount**​ ​**of**​ ​**product**​ ​**produced**​ ​**is**​ ​**restricted**​ ​**to the**​ ​**amount**​ ​**of**​ ​**the**​ ​**excess**​ ​**reactant**​ ​**that**​ ​**reacts**​ ​**with**​ ​**the**​ ​**limiting**​ ​**one**​ ​**(so**​ ​**use amount**​ ​**of**​ ​**limiting**​ ​**reagent**​ ​**not**​ ​**one**​ ​**in**​ ​**excess**​ ​**for**​ ​**calculations)**

how to calculate volume of a gas

**Volume**​​**of**​​**gas**​​**(dm**​**3)**​ ​​**at**​​**RTP**​​**=**​​ **Moles**​​**x**​​**24**

what is concentration

the amount of substance in a certain volume of a solution

more solute there is in a given volume the more concentrated the solution

how to calculate concentration of solutions

concentration (g/dm³) = mass of solute(g) / volume of solvent (dm³)

concentration (mol/dm³) = mass of solute(mol) / volume of solvent (dm³)

relationship between volume, mass and concentration

*  **a**​ ​**smaller**​ ​**volume**​ ​**or**​ ​**larger**​ ​**mass**​ ​**of**​ ​**solute**​ ​**gives**​ ​**a**​ ​**higher**​ ​**concentration**
* **a**​ ​**larger**​ ​**volume**​ ​**or**​ ​**smaller**​ ​**mass**​ ​**of**​ ​**solute**​ ​**gives**​ ​**a**​ ​**lower**​ ​**concentration**

divide by 1000 to convert from cm³ to dm³

cm³ to dm³

dm³ to cm³

multiply by 1000 to convert from dm³ to cm³

mol/dm³ to g/dm³,

to convert from mol/dm³ to g/dm³, multiply by the relative formula mass

g/dm³ to mol/dm³,

to convert from g/dm³ to mol/dm³, divide by the relative formula mass