Chemical reaction

ChemistryHow do we know a chemical reaction has

taken place?

ChemistryHow do we know a chemical reaction has

taken place?

ChemistryHow do we know a chemical reaction has

taken place?

ChemistryHow do we know a chemical reaction has

taken place?

we know a chemical reaction has taken place if we observe:

-Colour change precipitate (solid is formed)-gas or gases are produced-change in mass-light is given out-change in temperature (cold or hot)

Review cover lessonStarter.match

CH4 NaClC6H12O6

Extension-name them. METHANE GLUCOSETABLE SALT

Some info.

• You will be tested on this topic G Tuesday 12.05.15

• You will not be tested on topics K and L until the June exam.

• June exam info is all on my web.

Practical-Follow the power point first then complete the practical.

SafteyRemember clear desksHOT things look like COLD things…if your not sure DO NOT touch it!

EXPLAINING CHEMICAL REACTIONS

1. WHY DO SOME REACTIONS GIVE OUT HEAT ? E.g. the chemical reaction between iron and sulfur.

IRON

+

SULFUR IRON SULFIDE

First we have to add some heat to break the bonds between the reactants

IRON

+

SULFUR

When the new bonds are made we get back energy

IRON SULFIDE

EXPLAINING CHEMICAL REACTIONS

1. WHY DO SOME REACTIONS GIVE UT HEAT ?

IRON

+

SULFUR IRON SULFIDE

Iron sulfide

• Atoms in compounds made of a metal and a non-metal do not form simple molecules like FeS

Fe S

Iron sulfide

• They form LATTICES a regular arrangement of atoms in the RATIO of 1:1 (one Fe for every 1 S)

Practical-Follow the power point first then complete the practical.

SafteyRemember clear desksHOT things look like COLD things…if your not sure DO NOT touch it!

Addition reaction-Iron sulfide FeS(fools gold)

1. State 3 properties of iron2. State 3 properties of sulfur3. Does the mixture or iron and sulfur have these same properties?4. How could you separate a mixture or iron and sulfur?5. Now put 1 spatula of the iron and sulfur mixture into an ignition tube, place

mineral wool in the top of the tube.6. Using test tube holder heat in the hottest part of a Bunsen flame (top of the

inner cone) POINT AWAY from people when you heat.7. After 1 min take out of the flame and note any observations.8. Heat for a further 5 mins then place on a heat proof matt.9. Move on to the other practical's whilst the tube cools down.10. Describe the iron sulfide you have made11. Does it have any of the properties of the iron or the sulfur?12. How could you tell a chemical reaction had taken place?13. Why did the mixture glow when you removed it from the heat after 1 min ?14. What is wrong with this diagram of iron sulfide15. Correct the diagram.

Fe S

Decomposition reaction-Copper carbonate

Decomposition means to break apart.These involve splitting up substances so we usually need to ADD heat to break the bonds between the reactants.Metal carbonates can be heated to produce a metal oxide and carbon dioxide.

e.g. MgCO3 MgO + CO2

Decomposition reaction-Copper carbonate

Metal carbonates can be heated to produce a metal oxide and carbon dioxide.

e.g. MgCO3

MgO + CO2Reactant Product

Decomposition reaction-Copper carbonate

We can test for the product carbon dioxide by bubbling the gas through lime water. A positive test will turn the lime water cloudy.

e.g. MgCO3

MgO + CO2

Lime water turns cloudy

or milky

Decomposition reaction-Copper carbonate

1. Set up apparatus as shown in the diagram.2. Heat 3 spatulas of Copper carbonate in the hottest part of a Bunsen flame (use tongs) until you

see the limewater turn cloudy.3. REMOVE LIMEWATER test tube BEFORE you remove copper carbonate from the heat.4. Describe copper carbonate.5. Describe copper oxide6. Describe carbon dioxide7. Write a chemical equation for the reaction.8. What was the reactant? 9. What were the products?10. Lead carbonate reacts in a similar way to copper carbonate.Write a word equation for this reaction

Write a chemical equation for this reaction.

11.How could you demonstrate that carbon dioxide was given off.

Extension: Why did you need to add so much heat to make this reaction happen ? (link to addition reaction bond breaking and making).

Precipitation reactions

Some chemical reactions occur without heating.If the REACTANTS are soluble but one of the PRODUCTS is insoluble a PRECIPITATE (suspended solid) will form.

Precipitation reactions

e.g. Double displacement reactions.

SodiumCarbonate

CopperSulfate

CopperCarbonate

SodiumSulfate

Solubleaq Soluble

aqSolubleaq

InsolublePrecipitates

Precipitation reactions

e.g. Double displacement reactions.

Solubleaq Soluble

aqSolubleaq

InsolublePrecipitates

Precipitation reactions1. Describe copper sulfate solution.2. Is copper sulfate soluble?3. Describe sodium carbonate solution4. Is sodium carbonate soluble 5. Mix 2cm3 of copper sulfate solution with 2cm3 of sodium carbonate solution and record your

observations.6. Write a word equation for the reaction.7. All sodium salts are soluble. In the reaction you have just done what is the name of the precipitate

?8. Lead nitrate and sodium iodide are mixed, write a word equation for the reaction.9. One of the products makes a precipitate, name the product..10. What is a precipitate?

Extension1. Describe the solutions lead nitrate and potassium iodide.2.Add two drops of lead nitrate to 2 drops of potassium iodide.3. Describe the productsWrite a word equation for the reaction 4. Describe Mg and oxygen.EYES!!!!5.Heat Mg in a blue bunsen flame6. Remove from the flame.7. Describe the product8. Write word equation for the reaction9.A star Q ‘’why does the Mg continue to burn after you have removed it from the heat.