Activity series

Experiment # 15

What we are doing today:

• We are going to test reactions of metals with acids • We are going to test single replacement reactions. •We are going to determine a relative activity series BASED ON OUR EXPERIMENTAL DATA

What does reactivity mean?

9F Reactivity in chemistry

To compare the reactivity of different elements, we might see how easily they react with oxygen.

Some metals corrode in minutes out on the bench.

Others take longer to corrode, unless you heat them.

Elements that are reactive readily take part in reactions with other chemicals.

9F The Gold Cup again?

We can list metals in order of how quickly they react with oxygen.

This ranking of metals according to reactivity is called the reactivity series.

Element Reactivity

LiRbKBaCaNaMgAlMnZnCrFeNiSnPbH2

CuHgAgPtAu

Halogen ReactivityF2

Cl2

Br2

I2

Ca

What if we react different metals with acid?

9F Reaction of metals with acid

copper – no bubbles, no reaction with acid magnesium – the metal reacts quickly with the acid, producing lots of bubbles

iron – the metal reacts slowly, producing a few bubblessodium – the metal bursts into flames, a very strong reactionlead – the metal reacts very slowly, producing very few bubbles

9F Feeling a bit displaced?

A single replacement reaction happens when one metal replaces another one in a compound.

Magnesium is more reactive than copper.

magnesium + copper sulphate magnesium sulphate + ?

Magnesium displaces copper from copper sulphate solution.

9F A model for displacement reactions

Write a word equation for this reaction.

This model will help explain displacement reactions. Think of reactivity as aggression!

Activity series

• The higher up in the chart, the more reactive the metal.

• Only metals higher on the chart can displace a metal below it

Element Reactivity

LiRbKBaCaNaMgAlMnZnCrFeNiSnPbH2

CuHgAgPtAu

Halogen ReactivityF2

Cl2

Br2

I2

Fe II (s) + 2CuSO4 (aq) 2Cu(s) + Fe(SO4)2 (aq)

Part A

• To six test tubes add approximately 0.5 ml of HCl

• Add a small piece Ca metal to the test tube

• Record all changes

• Repeat for all five metals

• Write complete and ionic equations for each metal

Part B

• To one test tube add approximately 0.5 ml of a polyatomic ionic compound Ca(NO3)2

• Repeat for each of the other six polyatomic ionic compounds

• Add a small piece Ca metal to each test tube• Record all changes• Repeat for all five metals• Write complete and ionic equations for each metal

Part B

• Dispose of the waste and Repeat all procedures for each of the other five metals

• Write complete and net ionic equations for each metal

Part C

Based on your experimental data determine a relative activity series of the metals in question

CaCuFeMgSnZnAl

Types of chemical equationsEquations can be divided into 3 types 1) Molecular, 2) Ionic, 3) Net ionic

• Here is a typical molecular equation:Cd(NO3)2(aq) + Na2S(aq) CdS(s) + 2NaNO3(aq)

• We can write this as an ionic equation• (all compounds that are (aq) are written as

ions):

Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)

CdS(s) + 2Na+(aq) + 2NO3

–(aq)

Net Ionic equations

Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)

CdS(s) + 2Na+(aq) + 2NO3

–(aq)

• To get the NET ionic equation we cancel out all terms that appear on both sides:

Net: Cd2+(aq) + S2–(aq) CdS(s)

Equations must be balanced• There are two conditions for molecular, ionic,

and net ionic equationsMaterials balance

Both sides of an equation should have the same number of each type of atom

Electrical balanceBoth sides of a reaction should have the same net charge

Due next week

• Pg 167 and 168

• Need to show all work for full credit!!