Post on 31-Dec-2015
transcript
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.
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