CHEMICAL

REACTIONS

BELL RINGER QUESTION Name two signs of a chemical reaction.

Here are the signs of a chemical reaction that we saw in yesterday’s lab.Color ChangeRelease of GasFormation of a precipitateChange in temperature

SYNTHESIS REACTION A synthesis reaction is one in which two

or more substances react to produce a single product.

The generic equation for a synthesis reaction is listed below:

A + B AB

SYNTHESIS REACTION CONT. When two elements react to form a

product the reaction is always considered a synthesis reaction.

2Na (s) + Cl2 (g) 2NaCl (s)

SYNTHESIS REACTIONS CONT. Synthesis reactions can also apply to

compounds.

Example:

CaO (s) + H2O Ca(OH)2(s)

SYNTHESIS REACTIONS CONT. This type of reaction can also apply to a

reaction with an element and a compound.

Example:2SO2 (g) + O2 (g) 2SO3 (g)

SYNTHESIS

REACTION VIDEO

http://www.youtube.com/watch?v=9_Nk_5Ui8Po

http://www.youtube.com/watch?v=ofDpg5rlBOs

http://schools.utah.gov/curr/science/sciber00/8th/matter/images/SYNTHES.GIF

COMBUSTION REACTIONS In a combustion reaction oxygen

combines with a substance and releases energy in the form of heat and light.

Combustion reactions are quite common because Oxygen may combine with many different substances.

COMBUSTION REACTIONS CONT. In this example, the reaction between

hydrogen and oxygen. When hydrogen is heated, water is formed and a large amount of energy is released.

2H2 (g) + O2 (g) 2H2O (g)

COMBUSTION REACTIONS CONT. Coal when burned is another example of

a combustion reaction.

A large amount of energy is released when coal is burned.

Questions: Can you think of some examples of coal

being used for energy? What is coal classified as? (hint it’s part of a

product that we use every day to get to school)

COMBUSTION REACTIONS CONT. Some combustion reactions may be

considered synthesis reactions as well.

COMBUSTION REACTIONS CONT.

http://www.elmhurst.edu/~chm/onlcourse/chm110/labs/world3images/lab2b.GIF

COMBUSTION

REACTIONVIDEOS

http://www.youtube.com/watch?v=Os-EhqrpMGc•Pumpkin Demonstration

http://www.youtube.com/watch?v=BsL_ztNvbek•Pringles Can Demonstration

http://www.youtube.com/watch?v=-DjCum6yu8M&feature=related•Whoosh Bottle

http://media-2.web.britannica.com/eb-media/63/124363-004-81232F4C.jpg

DECOMPOSITION REACTIONS A decomposition reactions is one in

which a single compound breaks down into two or more elements or new compounds.

The generic Example:

AB A + B

DECOMPOSITION REACTIONS CONT. Decomposition reactions often require

an energy source.

What kinds of energy do you think it this reaction would typically require?

DECOMPOSITION REACTIONS CONT. A decomposition reaction is one in which

a single compound breaks down into one more products.

Examples:NH4NO3(s) N2O(g) + 2H2O(g)

2NaN3(s) 2Na(s) + 3N2(g)

DECOMPOSITION REACTIONS CONT.

Can you think of any real world examples of a decomposition reaction?

http://graphics8.nytimes.com/images/2006/12/19/business/19auto.1_600x333.jpg

DECOMPOSITION REACTION

VIDEOhttp://www.youtube.com/watch?v=hWiWjWHdHXM•Elephant Toothpaste

http://www.youtube.com/watch?v=UhfNBEqucE8&feature=related•Airbag deployment

http://www.youtube.com/watch?v=Q9zcnCQOlx4

http://genchem.chem.wisc.edu/demonstrations/Images/12kinetic/permanganate.jpg

Decomposition of hydrogen peroxide by permanganate

SINGLE REPLACEMENT REACTIONS A single replacement reaction is one in

which the atoms of one element replace the atoms of another element in a compound.

The generic example:

A + BX AX + B

SINGLE REPLACEMENT REACTIONS CONT.

Example:

Cu(s) + 2AgNO3(aq)

2Ag(s) + Cu(NO3)2(aq)

http://www.chemistry-blog.com/wp-content/uploads/2009/04/before1.jpg

SINGLE REPLACEMENT REACTIONS CONT. Example:

2Li(s) + 2H2O(l)

2LiOH (aq) + H2(g)

http://1.bp.blogspot.com/_rfhv4lPQhSY/Swclcaaax-I/AAAAAAAAAo8/_mbFcN0yO7o/s1600/Lithium+and+water.jpg

SINGLE REPLACEMENT REACTIONS CONT. A metal will not always replace another

metal in a compound dissolved in water.

It depends on the reactivity of the metal. A metal’s reactivity is its ability to react with another substance.

Go to figure 10-10, p. 288 in your textbook to see the activity series.

ACTIVITY

SERIES http://castlelearning.com/

review/reference/chem%20table%20j.gif

SINGLE REPLACEMENT REACTIONS CONT. Another type of single replacement

reaction involves the replacement of a nonmetal in a compound by another nonmetal.

Halogens are typically involved in these kinds of reactions.

Halogens, like metals, have different levels of activity.

SINGLE REPLACEMEN

TREACTION

VIDEOS

http://www.youtube.com/watch?v=ul4xRy8hcsQ•Copper & Silver Nitrate

http://www.youtube.com/watch?v=hKtynbVtMKc

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG05_06-02UN.JPG

DOUBLE REPLACEMENT REACTIONS

A double replacement reaction is a chemical reaction that involves the exchange of positive ions between two compounds and produces either a precipitate, a gas, or water.

DOUBLE REPLACEMENT REACTIONS CONT.Generic Equation:

AX + BY AY + BX

A and B represent the positively charged ions. X and Y represent the negatively charged ions.

In a double replacement reaction X will replace Y.

The ions switch sides with the ion most like it. So in other words each ion will either switch with the other positive ion if it’s positive or vise versa.

DOUBLE REPLACEMENT REACTIONS CONT.Examples:

Ca(OH)2(aq) +2HCl(aq) CaCl2(aq) + 2H2O(l)

2NaOH(aq) +CuCl2(aq) 2NaCl(aq) + Cu(OH)2(aq)

Looking at these two chemical reaction, identify the positively charged ions and the negatively charged ions. Write it down in your chemistry journals.

DOUBLE REPLACEMENT REACTIONS CONT. A key characteristic of a double

replacement reaction is the formation of a certain type of product. Either a,Precipitate

Which is a solid produced in solution during a chemical reaction.

GasWater

DOUBLE REPLACEMENT REACTIONS CONT. Table 10-2 from your textbook can be helpful

Guidelines for Double-Replacement ReactionsStep Example

1. Write the components of the reactants in a skeleton equation.

Al(NO3)3 + H2SO4

2. Identify the cations and anions in each compound.

Al(NO3)3 has Al 3+ and NO3-

H2SO4 has H+ and SO42-

3. Pair up each cation with the anion from the other compound.

Al3+ pairs with SO42-

H+ pairs with NO3-

4. Write the formulas for the products using the pairs from step 3.

Al2(SO4)3

HNO3

5. Write the complete equation for the double-replacement reaction

Al(NO3)3 + H2SO4 Al2(SO4)3 +HNO3

6. Balance the equation. 2Al(NO3)3+ 3H2SO4 Al2(SO4)3+ 6HNO3

DOUBLE REPLACEMENT REACTION

VIDEOShttp://www.youtube.com/watch?v=opY3FLrPTa4

http://www.youtube.com/watch?v=jrDV2-nsQ2g

http://elearning.flinnsci.com/Assets/product_images/1817_3_271.jpg

SUMMARY: TABLE 10-3 Predicating Products of Chemical

ReactionsClass of Reaction Reactants Probable Products

Synthesis •Two or more substances

•One compound

Combustion •A metal and oxygen•A nonmetal and oxygen•A compound and oxygen

•The oxide of the metal•The oxide of the nonmetal•Two or more oxides

Decomposition •One Compound •Two or more elements and/or compounds

Single-Replacement

•A metal and a compound•A nonmetal and a compound

•A new compound and the replaced metal•A new compound and the replaced nonmetal

Double-Replacement

•Two compounds •Two different compounds, one of which is often a solid, liquid or a gas

CONCLUSIONS Exit Ticket

Name one thing that you learned about chemical reactions today.

SOURCES Textbook:

Chemistry: Matter and Change. Copyright 2002. McGraw-Hill Companies, Inc.

Youtube All demonstration videos were taken from Youtube.

Links are on the PowerPoint Google Images

All of the images were taken from Google images (the websites are credited under the pictures).

All other images were taken from Microsoft PowerPoint ClipArt.