Making Insoluble Salts

Question 1

what is a precipitate?

Answer 1

an insoluble solid that forms inside a solution - the ions in the solution collide with each other, a precipitate forms and sinks to the bottom

Question 2

when mixing two solutions how can you tell a precipitate will form?

Answer 2

by mixing the ions up and seeing if either of the resulting compounds is insoluble - if an insoluble compound is formed, it will appear as a precipitate

Question 3

how to make salts by precipitation

Answer 3

• we make insoluble salts by mixing solutions to make a precipitate
• each solution should contain one of the ions needed to make it

Question 4

what are spectator ions?

Answer 4

ions that aren’t involved in making the precipitate and remain in the solution as ‘leftovers’

Question 5

what is an ionic equation?

Answer 5

a simpler equation for the reaction just involving the precipitate

Question 6

method to separate a salt that has been made by precipitation

Answer 6

1. filter out the salt precipitate - the residue is the salt we want to keep and the filtrate is the leftover solution
2. rinse the salt with water - this washes off traces of the leftover solution and it doesn’t dissolve our salt because it’s insoluble
3. dry the salt by dabbing it with filter paper - this removes the last few traces of water, leaving us with a pure dry salt