Unit 9E

Reactions of Metals

Learning Outcome

• Describe where to find metals on the periodic table

• Describe some properties of metals

The periodic tablehttp://www.youtube.com/watch?v=nsbXp64YPRQ

• Metals are on the left and centre.

• Non-metals are mostly on the right

• In between are metalloids – these are like metals in some ways and like non-metals in others.

Metals and non-metals have very different physical properties. Because of this the position of metals and non-metals show a pattern in the Periodic Table:

Metals and Non-metals

Properties of metalsMetals are all around us.We use them every day in a variety of forms.

With the person sitting next to youcreate a list of items that you use every day that are made from metals

Properties and Uses

Metals are used for a variety of reasonsbecause of their many properties.

Use the activity to sort out the property of metals with their uses.

Property Definition Suitability for use

Strength Able to withstand great force

bicycle frames, car bodies,

bridges

Density Mass per unit3 car bodies, horse shoes

Malleability Able to be shaped by rolling or hammering

Low densityaluminium in airplane bodies

Electrical conductor

Ability to conductan electricalcurrent

copper wires in cables

Thermal Conductor

Ability to conducta thermal current

Pots and pans for cooking

Learning Outcome

• State what gas is given off when a metal reacts with an acid.

• Describe a test for this gas.

Following the instruction card you havebeen given carry out the experiment.

Now discuss the results in your groups.

What happened to the light splint?

What did you notice about the rates of the reactionswhen you changed the metal?

gas

When some metals react with acid a ________ is released showing that a _________ reaction has taken place.When tested this gas _________ with a _______.

Copy and complete

chemicalBurnspop

From our experiment the reactivity of the metals is:

Learning Outcome

• Discover if the same gas is given off with every acid

• Describe a test for this gas.• Write a general formula for the

reaction of metals with acids.

Mg + acid

Lighted spill

Oxygen in the air

What is the gas and is it the same for every reaction of metal with acid?

When you tested some metals with hydrochloric acid a gas was given off.

This gas burned with a ‘POP’

Look at the chemical equation below

Mg + HCl +

magnesium + hydrochloric acid

magnesium chloride

+ hydrogen

H2MgCl2

From the equation above the gas must be _____________Hydrogen

Will the same gas be

given off if we change

the acid that we used??

Carry out the experiment as described on the

Experiment work card.

What did you discover about the gas released?

Draw a labelled diagram to show the experiment you carried out.

Reaction with Metals - general

• Many metals react with acids to release a salt plus hydrogen gas.

• The general word equation is:

metal + acid a salt + hydrogen

• The salt will depend upon the metal and the acid used.

hydrogen+magnesium chloride

Hydrochloric acid

+magnesium

•Hydrochloric acid gives Hydrochloric acid gives metal chloridesmetal chlorides•Sulphuric acid gives Sulphuric acid gives metal sulphatesmetal sulphates•Nitric acid gives Nitric acid gives metal nitratesmetal nitrates

•So, for example

Zinc + hydrochloric + acid

Use the general equation and the examples below to write the word equations for the reactions you carried out.

metal + acid a salt + hydrogen

iron + nitric acid +

calcium + sulphuric acid

+

iron nitrate

calcium sulphate

zinc chloride

hydrogen

hydrogen

hydrogen

magnesium + sulphuric acid

+magnesium sulphate

hydrogen

Learning Outcome

• Describe the products of the reaction between metal carbonates and acids.

• Write a general formula for the reaction of metal carbonates with acids.

Carry out the experiment as described on the experiment work card.

Consider the questions below:

1. What happened to the lime water?

2. What is the gas that is released?

3. What happened to the colour of the original solution?

Draw and label a diagram to show what you did.

Copy and complete

The limewater changed from clear and _________to _________. This shows the gas produced is _________________. The solution originally was ___________ and changed to ___________ showing that a chemical reaction had occurred.

Metal carbonates and acids

Metal carbonate + acid a salt + water + carbon dioxide

• When metal carbonates react with acids they fizz giving off carbon dioxide gas.

• Most metal carbonates are not very soluble and so reactions may be slow.

sulphuric acid

+copper carbonate

water+calcium chloride

carbon dioxide

+

• Now write the word equation for the reaction you carried out.

The general word equation for thesereactions is:

Metal carbonates and acids

Metal carbonate + acid a salt + water + carbon dioxide

water+zinc sulphate

sulphuric acid

+zinc carbonate

ZnCO3 + H2SO4 ZnSO4 + H2O + CO2

+ carbon dioxide

water+sodium chloride

hydrochloric acid

+sodium carbonate

+ carbon dioxide

water+nickel nitrate

nitric acid+nickel carbonate

Na2CO3 + 2HCl 2NaCl + H2O + CO2

+ carbon dioxide

NiCO3 + 2HNO3 Ni(NO3)2 + H2O + CO2

Learning Outcome

• Describe the products of the reaction between metal oxides and acids.

• Write a general formula for the reaction of metal oxides with acids.

Metal OxidesWhat are metal oxides?

Metal oxides are formed when a metal reacts with oxygen

in the air.

Metal oxides and acids

• Most metal oxides are not soluble.

• This means their reaction with acids is often slower.

• Heating can help to speed up the reaction.

Acid

Oxide

sulphuric acid

+Copper oxide

copper sulphate

+ water

Carry out the experiment as instructed

Draw and label a diagram into your jotter

What did you notice?

Using the general equation you have been

given can you write the word equation for

the reaction you have just carried out?

Where is the salt??

Acid

Oxide

From your word equation you havecreated copper sulphate salt.

What could we do to extract the copper

sulphate from the water to check ourequation?

Metal oxides and acids

Metal oxide + acid a salt + water

water+zinc sulphate

sulphuric acid+zinc oxide

water+sodium chloride

hydrochloric acid

+sodium oxide

water+iron nitratenitric acid+iron oxide

ZnO + H2SO4 ZnSO4 + H2O

Na2O + 2HCl 2NaCl + H2O

Fe2O3 + 3HNO3 Fe(NO3)3 + 3H2O

Learning Outcome

• Describe what acid rain is and how it is formed

• Explain some of the problems associated with acid rain

• Describe some methods to reduce acid rain.

Your task……….

• Create an informative article for a newspaper. You must include – – Pictures– An explanation of what acid rain is– An explanation why acid rain is a

problem– Methods of reducing acid rain

Learning Outcome

• Be able to state what is formed when an acid reacts with metals, metal carbonates and metal oxides.

In your teams!!

You must create 3 sets of individual cardswith:Reactant namesArrowsProduct names

e.g.

Hydrochloric acid

Magnesium

Magnesium chloride

Hydrogen+ +

Once your cards are made:

You will pass your cards to the next group.

You will be passed cards by another group.

You now have 10 minutes to unjumble the cards you have been given and lay out on the desk in front of

you the correct answers

Now a runner from the group who made your cards will come and assess your answers!!

This will be added to the quiz scores!!!!

GOOD LUCK!

Learning Outcome

• Be able to explain what neutralisation is and what the products of neutralisation are.

Neutralisation

When an acid is added to an alkali or an alkali added to anacid, neutralisation takes place: the substance changespH to become closer to being neutral.

In your group think about examples from everydaylife where neutralising an acid or an alkali mightbe useful. Write your ideas onto a show me board.

Alkali HazardsAlkalis just like acids can be dangerous to use.

Weak alkalis like calcium hydroxide(lime water) are irritants and cancause skin to redden and itch and blister.

Strong alkalis like sodium hydroxide(caustic soda) are corrosive and cancause skin to redden and itch and blister.

Learning Outcome

• Describe what an ion is.• Explain how salts are formed from

ions.

Bases

Bases are substances that neutralise acids.

Bases are usually:•Metal hydroxides contain OH•Metal oxides contain O•Metal carbonates contain CO3

The following general word equation describes neutralisations:

acid + base a salt + water

In the case of carbonates we also get carbon dioxide.

Alkalis

Bases are substances that neutralise acids.

Alkalis are soluble bases.

Although both can neutralise acids solubility is important when it comes to the pH of solutions. For example, adding sodium hydroxide to water gives a solution with a pH of about 14.

When calcium carbonate is added to water it does not dissolve and so the pH remains close to 7. Even so it can neutralise acid that is added although more slowly than a soluble base might.

Neutralisation - Indigestion

If we have too much acid in our stomachs, we get indigestion.

Acid can move up out of our stomach creating a burning feeling in the chest.

We neutraliseneutralise the excess acid by taking a tablet containing a base.

This is usually a carbonate or an oxide.

Strong soluble bases (like sodium hydroxide) would create too alkaline a solution and cannot be used.

AlkaliAcid 1 2 14131211109876543

Neutralisation - Stings

A bee sting is acidic.

One way to treat a basicbasic wasp’s sting is with an acidacid : vinegar - ethanoic acid.

So one way to treat an acidicacidic bee sting is to dab on a basebase: bicarbonate of soda more properly known as sodium hydrogen carbonate.

A wasp sting is alkaline.

Neutralisation – Soil pH

Many plants won’t grow well in acid soil and so farmers have to regularly check the pH and adjust it by adding a base.

Plants remove compounds from the soil in a way that tends to leave the soil acidic.

Calcium carbonate or calcium hydroxide are cheap and so are often used for this purpose.

Neutralisation – Soil fertilisers

Ammonia is a water soluble gas high in nitrogen and in some countries it is injected directly into moist soil. However, because it is a gas much of it is quickly lost.

In the UK ammonia is dissolved in water to give ammonium hydroxide (an alkali) and this is neutralised by reacting it with nitric acid to give a solid nitrogen rich fertiliser.

Plants also remove nitrogen compounds from the soil and this is often replaced using fertiliser.

water+ammonium nitrate

nitric acid+ammonium hydroxide

NH4OH + HNO3 NH4NO3 + H2O

The gases are “scrubbed”, as much as possible, of these acidic oxides by reacting them with a base before releasing them into the air.

Many power stations burn coal containing sulphur.

When this burns it produces acidic sulphur oxides which can cause acid rain.

Calcium oxide or calcium hydroxide are often used for this purpose.

Neutralisation - acid gases

Steps have been taken to reduce emissions of acidic sulfur oxides from power stations and nitrogen oxides from cars.

Even so the atmosphere still contains enough of them to make the rain from industrial areas quite acidic.

Acid rain – living things

Trees and lakes are badly affected in many parts of the world including Northern Germany and Scandinavia which suffers from South-West winds from the UK.

Acid rain damaged tress

Acid rain increases the rate of corrosion of metals.

Acid rain – metals and stone

The metal above the wheel arch of this car is rusting away

It also greatly accelerates the rate of chemical weathering of certain stones used in building such as limestone and marble. (These stones are carbonates. What gas will be given off as they dissolve?)

CO2

Learning Outcome

• Understand the hazards of alkalis• State what a base is• State what an alkali is• Explain the importance of the

solubility of a base in neutralisation

Copy and completeBases are substances that _________ acids. When a base is soluble in water it is called an ___________.An insoluble base will not alter the pH of ________but will still neutralise an acid although more ________.

Alkalis are important in a number of situationse.g. neutralising acidic soil.

Learning Outcome

• Describe 2 ways to find the exact volume of 1 substance that will neutralise another substance

A simple way of neutralising a solution is to add an acid toAm alkali until the indicator turns green.

Using a dropping pipette makes it very difficult to measure the exact volume of alkali or acid required for the reaction.

Chemists use burettesto add small amountsgradually and to measure volume added accurately.

Finding the volumeExperiment 1• Fill the burette with HCl• Accurately measure 25cm3

of NaOH (using a pipette) into a conical flask

• Add 2 drops of universal indicator

• Now carefully add HCl from the burette into the conical flask as shown.

• Record the volume of HCl needed to neutralise the NaOH.

Experiment 2• Accurately measure 25cm3

of HCl into a beaker• Collect a pH probe and

data logger and insert the pH probe into the HCl

• Now measure 1cm3 of NaOH and add it into the HCl.

• Stir and record the pH • Add another 1 cm3 of

NaOH and repeat.• Keep adding until the pH

on the data logger reads 7.

.

Graph the results

Create a graph of pH of solution against

the volume of NaOH added.

Using your graph find the exact volumeneeded to neutralise the HCl.

Homework

Write a short essay (300 words) on salts and theircommercial and industrial importance in society.

Learning Outcome

• Describe 2 ways to find the exact volume of 1 substance that will neutralise another substance

Learning Outcome

• Describe 2 ways to find the exact volume of 1 substance that will neutralise another substance

Learning Outcome

• Describe 2 ways to find the exact volume of 1 substance that will neutralise another substance