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 slowly sinks to the bottom

Question 2

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

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

making salts by precipitation explaination?

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

for example to make BaSO4 we could mix: BaCl2 + Na2SO4

Question 4

what are ions called that are not involved in making the precipitate?

Answer 4

spectator ions and they remain in the solution as ‘leftovers’

Question 5

if we write the equation without including the spectator ions, just the precipitate formula, what is this called?

Answer 5

an ionic equation

Question 6

method of separating salt from the solution after being made by precipitation

Answer 6

1. filter out the salt precipitate - the residue is the salt we want to keep, the filtrate is the leftover solution
2. rinse the salt with water - this washes off traces of the leftover solution, 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