Ions in Solids and Solutions, ppt reactions

Question 1

are K+, Na+ and NH4 + compounds soluble or insoluble?

Answer 1

soluble

Question 2

are nitrates soluble or insoluble?

Answer 2

soluble

Question 3

are sulfates soluble or insoluble & are there any exceptions?

Answer 3

all sulfates are soluble, except Ca2 +, Sr2 +, Ba2 +, Ag+, Pb 2+ sulfates which are insoluble

Question 4

are Cl-, Br- & I- compounds soluble or insoluble and are there any exceptions?

Answer 4

all are soluble except Ag+ and Pb 2+ which are insoluble

Question 5

are carbonates soluble or insoluble and are there any exceptions?

Answer 5

all carbonates are insoluble except Na+, K+ and NH4 + carbonates which are soluble

Question 6

are hydroxides soluble or insoluble and are there any exceptions?

Answer 6

all hydroxides are insoluble, except Na+, K+, NH4 +, Sr 2+, Ba 2+ hydroxides which are soluble

Question 7

what is formed when mixing OH- solution with Cu 2+?

Answer 7

blue ppt of Cu(OH)2

Question 8

what is formed when mixing OH- solution with Fe 2+?

Answer 8

dirty green ppt of Fe(OH)2

Question 9

what is formed when mixing OH- solution with Fe 3+?

Answer 9

orange-brown ppt of Fe(OH)3

Question 10

what is formed when Pb 2+ is mixed with iodide ions?

Answer 10

bright yellow ppt of PbI2

Question 11

what happens when an acid solution is added to a solution containing carbonate ions?

Answer 11

CO2 gas is given so the solution fizzes

Question 12

what is formed when a solution containing barium ions is added to a solution containing sulfate ions?

Answer 12

a white ppt of BaSO4

Question 13

what is the method for making a soluble salt from an acid with an insoluble base, carbonate or metal?

Answer 13

• half fill a beaker with acid solution
• add the solid base, carbonate or metal a spatula at a time until excess has been added (so we know all the acid has gone)
• filter the mixture to remove the excess solid
• evaporate off most (but not all) of the water then leave the salt to crystallise

Question 14

method for making a soluble salt from an acid + alkali both in solution

Answer 14

• carry out an acid-alkali titration using an indicator to see the end point
• once you know the average titre, repeat the titration without the indicator, adding that precise volume from the burette
• evaporate off the water to get the salt crystals
• wash the crystals
• dry the crystals

Question 15

method for making an insoluble salt from solutions of 2 soluble salts by precipitation

Answer 15

• mix together solutions of 2 suitable soluble salts
• the insoluble salt will appear as a solid ppt. filter the mixture, the salt is the solid on the filter paper
• wash it by rinsing it will distilled water
• scrape it onto a watch glass or fresh filter paper and leave it to dry