CHEMISTRY

Bryan Terán & Andrea Alonso

Precipitation in Double Displacement Reactions

• In this lab activity we have to observe precipitation reactions by mixing aqueous solutions of cations and anions.

• We have to Indicate which 2 cations form the most precipitates.

Materials for the practise• Pb(NO3)2

• KI• NaOH• Na2CO3

• AgNO3

• KNO3

• CaCl2• NaCl• FeCl3• CuSO4

• Test tubes• Test tubes rack

Procedure1- Place 21 clean test tubes

in a test tube rack2- Add 6 drops of the solution

indicated at the worksheet to 7 clean test tubes

3- Add 6 drops of AgNO3,

Pb(NO3)2 and CaCl2 solution to every test tube

EXEMPLES

4- Observe and record information and color of precipitates formed

For example … Pb ( NO 3)2 reaction with NaCl to form PbCl2 and Na(NO3)

• But one of the new compounds are not soluble and precipitates are formed

• The Cl- ions aren’t soluble with Pb++.

Pb(NO3)2 + NaCl PbCl2 + NaNO3 white

More exemples …

This reaction between AgNO3 and KI, forms AgI and KNO3.The Ion I- isn’t soluble with Ag and forms precipitates.

At the end…

• After mixing all the compounds and balance the reactions…

…5- We must tidy and clean all the materials

REMEMBER! • We must not

make any reaction without the supervision of our teacher FELISA PINILLA.

VERY IMPORTANT!!And even

more important,- not to

ingest any material…