2.4 - Reactivity Series

Potassium Sodium Lithium Calcium Magnesium Aluminium (carbon) zinc Iron (hydrogen) Copper Silver Gold

Magnesium powder and Copper(II) oxide are mixed together and heated very strongly at the end traces of magnesium oxide are left on the ceramic paper Magnesium + Copper(II) oxide > Magnesium oxide + copper Example of a displacement reaction. Less reactive metal, copper has been displaced from its compound by th more reactive magnesium. Any metal higher in the reactivity series will displace one lower from a compound However heating copper with magnesium oxide nothing would happen because copper is less reactive than Magnesium. Copper isn’t capable of displacemnt

A black mixture of carbon and copper(II) oxide is heated in a test tube .The mixture glows red hot because of the heat given out during the reaction and left with pink-brown copper in the tube. C + 2CuO > CO2 + 2Cu Carbon is above Copper in the reactivity series and displaces copper from Copper(II) Oxide

A substance has been oxidised if it gains oxygen. Oxidation is gain of oxygen.

A substance has been reduced if it loses oxygen. Reduction is loss of oxygen

Oxidation IS Loss Reduction Is Gain

A redox reaction is one in which both reduction and oxidation occours Oxidation and reduction always occour together because if something loses oxygen, something else must gain

A reducing agent is a substance that reduces something else. A reducing agent always gets oxidised in a chemical reaction because it takes the oxygen away from something else and therefore gains oxygen itself.

A substance that oxidises something else. An oxidising agent always gets reduced in a chemical reaction because it oxidises something else by giving away its oxygen

In a reaction between Magnesium and copper (II) oxide. Magnesium and the copper are metals are made of metal atoms. Copper (II) oxide and Magnesium Oxide are both ionic compounds CuO contains CU2+ and O2- ions, and MGO contains Mg2+ and O2-. O2- ions does not change Mg atoms are turned into Magnesium ions. Mg atoms lose electrons to form Mg ions. These electrons are gained by the copper ions to form copper atoms redox reaction.

The Copper is displaced by the more reactive zinc. Blue colour of the Copper (II) sulfate solution fades as colourless zinc sulfate is formed Zn + CuSO4 > ZnSO4 + Cu Ionic compounds formed sulfate is a spectator iron.

An oxidising agent is something that oxidises something else by taking its electrons away from it. Oxidising agents accept electrons and therefore are reduced in a reaction A reducing agent is something that reduces something else by giving electrons to it. Reducing agents give away electrons and therefore are oxidised. In reaction between Zinc and copper Zinc reduces copper giving it electrons ZN is reducing agent. Zinc is oxidised.

Silver below copper in reactivity series. CU + 2AgNO3 > Cu(NO3)2 + 2Ag Nitrate ions are spectator ions Cu + 2Ag+ > Cu2+ + 2Ag This is a redox reaction Cu is reducing agent (it is oxidised) because it gives electrons to the Ag+ ions to reduce them to Ag. Ag+ ion is the oxidising agent (It is reduced) becuase it take away electrons away from the Cu atoms.

Metals above hydrogen in the reactivity series react with water to produce hydrogen. If the metals reacts with cold water metal hydroxide and hydrogen are formed this is the same with steam Metal + Steam/Cold water . Metal oxide + hydrogen As moving down the reactivity series reactions become less vigorous Metals below hydrogen in the reactivity series such as copper don’t react with water or steam

Very vigorous reactions less violent moving down. 2M + 2H20 > 2MOH + H2

Calcium reacts gently with cold water. Grey granules sink but are carrier back to the surface as bubbles of hydrogen are formed around them. Mixture becomes warm. Calcium hydroxide forms not very soluble in water some does to form a white insoluble solid.

Almost no reaction. Unless very clean bubbles will form. But reaction stops again this is because magnesium becomes coated with insoluble magnesium hydroxide.

Magnesium ribbon can be heated in steam using delivery tube mineral wool soaked in water. Mineral wool is not heated directly. Enough heat move back along the test tube to turn the water to steam Burns with bright white flame producing hydrogen can be ignited to to produce white magnesium oxide.

Zinc and Iron the hydrogen comes off slowly to be collected. With Zinc Zinc oxide is formed. This is yellow when its hot white on cooling. With Iron Iron becomes slightly darker grey complicated oxide formed

Method: Set up four test tubes and about 2cm3 of dilute hydrochloric acid into each one Put a small peice of Magnesium, Zinc, iron or copper into each of the test tube If fizzing collect or trap gas and test with lighted splint a squeaky pop test indicated H2 gas Repeat experiments with dilute sulfuric acid

Magnesium - Reacts vigorously with a lot of fizzing. Produces hydrogen. Colourless solution formed very hot test tube Zinc - Steady reaction. Fizzing. Enough gas eventually collected to produce a squeaky pop with a lighted splint. A colourless solution formed. The test-tube gets warms Iron - Slow fizzing. Very little gas collected in time available. A very pale green solution formed. Test tube gets slightly warmer. Copper - No change These reactions exothermic. Now noticed a temp change measure the temp change to compare the reactivity of the metals.

Volume and concentration of hydrochloric acid. The mass of the metal. Surface area of the metal..

Measure out 50cm3 of 1 mol/dm3 hydrochloric acid using a measuring cylinder. Pour the hydrochloric acid into a polystyrene cup Measure Inital temperature of hydrochloric acid Weigh out 0.010 mol of magnesium powder Add the magnesium powder to the polystyrene cup, stirring rapidly, and measure the maximum tempreture reached Repeat with other metals using 0.01 metals.

Metals above hydrogen react with acids to form a salt and hydrogen. Higher the metal in the series the more violent reaction Metal + Acid > Salt + Hydrogen Metal + dilute sulfuric acid > metal sulfate + hydrogen