C3.2 Quantitative Analysis Flashcards
What is a mole?
A number of atoms (6.023 * 10^23)
Why are moles used?
I mole will always be the same number of particles in that amount for any element.
How do you work out moles?
Mass in g / Atomic mass
What is the formula for concentration?
Mass / Volume
How do you work out mole concentration?
Mass concentration / Atomic number
How do you work out mass concentration?
Mole concentration * Atomic mass
What two methods can remove permanent hardness in water?
An ion exchange column and adding sodium carbonate.
What is the generic formula for working out the concentration of the acid from a titration?
Moles = concentration * volume
Work outvhow many moles of one substance you need compared to the other. If it is 1:2, then :
Moles/ 2 then /(concentration/1000)
What are the two methods that you can use to make a soluble salt?
Using an acid and an Insoluble reactant
Using an acid and a soluble reactant
How do you make a soluble salt using an acid and an insoluble reactant?
Add the base to the acid until it is in excess and sinks to the bottom.
Filter out the excess solid and heat the solute (salt and water) until all the water has evaporated
How do you make a soluble salt from an acid and a soluble reactant?
You need to carry out a titration first to find the volume of acid needed to neutralise the base. The add that volume of acid and alkali together without indicator and heat the solution that is left.
25 cm3 of NaOH reacts with 0.1 mol HCl. An average of 20cm3 HCl was needed to react the NaOH completely. What is the concentration of the Sodium Hydroxide?
Work out number of moles of HCl so 0.1 (concentration) * (20/1000) = 0.002 moles of HCl present.
Write out the balanced equation to work out how many moles of acid reacted with how many moles of alkali.
0.002 moles of HCl reacts with 0.002 moles of NaOH.
0.002/0.025 = 0.08 mol dm-3
