AQA AS Physical Chemistry - The Mole & Solutions PDF

AS CHEMISTRY 3.1.2 AMOUNT OF SUBSTANCE THE MOLE & SOLUTIONS n = number of moles c = concentration (mol.dm-3) (moles per decimeter cubed) V = volume (dm3)...

AS CHEMISTRY 3.1.2 AMOUNT OF SUBSTANCE THE MOLE & SOLUTIONS n = number of moles c = concentration (mol.dm-3) (moles per decimeter cubed) V = volume (dm3) How To Calculate This is the number of Moles & Concentration moles of a substance that n you have dissolved per unit volume in solution (aq) c V (or sometimes gases) Volume MUST be in dm3! For context, think of concentration as the number of moles that are present per unit volume. e.g. 0.1 moles per decimeter cubed. ALTERNATIVE UNITS OF CONCENTRATION Sometimes you will see concentration given in g.dm-3. i.e. grams per decimeter cubed THE CONVERSION g.dm-3 to mol.dm-3 : divide by the Molar Mass (Ar, RFM or Mr) of the substance. mol.dm-3 to g.dm-3 : multiply by the Molar Mass (Ar, RFM or M) of the substance. AQA www.chemistrycoach.co.uk © scidekick ltd 2024 AS CHEMISTRY 3.1.2 AMOUNT OF SUBSTANCE HINTS | TIPS | HACKS Understand what “concentration” means! “The number of moles present in 1 decimeter of solution”. Square brackets denote “concentration” e.g. [H+] = “concentration of H+ ions” Dilute = low amount of substance per unit volume Concentrated = high amount of substance per unit volume IONS IN SOLUTION When you dissolve an ionic substance in water it dissociates (splits) into its individual ions. Check the formula of the salt for the concentration of ions. A 1.00 mol.dm-3 solution of barium chloride [Ba2+] = 1.00 mol.dm-3 [BaCl2] 1.00 mol.dm-3 [Cl-] = 2.00 mol.dm-3 How To Calculate Concentration of Ions in Solution AQA www.chemistrycoach.co.uk © scidekick ltd 2024