Assignment Worksheet on classification of chemical reactions Test

Assignment • Worksheet on classification of chemical reactions

Test Results-From before the holidays! Per 2 80% Per 3 82% Per 5 80% Per 7 83% Per 8 76% Da winna? Is there a surprise in the results today?

Homework review In the review book: Read page 37 -39. Do page 40, #44 -46, 49 -51, and 54 -56.

H in front is an acid. H in front is H+

Once oxygen is breathed in a spacecraft—how could it be recovered? Now , see if you can make a biology connection: plants do what with carbon dioxide? They break it into carbon and oxygen!! Humans eat plants and breath out carbon dioxide and water—so which process would help us get the oxygen back from Answer? the carbon. Decompose dioxide? it!!

Types of Chemical Reactions (con’t) 4. Double Replacement 5. Combustion

A third type: Single replacement. In these, one element replaces a second element in a compound. These happen in water (aqueous) so they are ionic compounds. In this case a “general formula” will help. A + BX AX + B Can you see how that worked? “A” displaced “B”. Zn(s) + Ag. NO 3 (aq) Zn. NO 3(aq) + Ag(s) But there is another way this can happen. Instead of replacing B, we replace X. A + BX Cl 2(g) + 2 Na. I(aq) BA + X 2 Na. Cl(aq) + I 2(s)

How to recognize? Learn to circle!! Let’s go back to the previous slide.

A third type: Single replacement (sometimes called displacement). In these, one element replaces a second element in a compound. Note: A is happen a neutral metal. Can(aqueous) you give some These in water soexamples? they are ionic compounds. BX is an ionic compound. What is B? Can you give examples? How about X? In this case a “general formula” will help. A + BX AX + B A + BX Can you see how that worked? “A” displaced “B”. Zn(s) + Ag. NO 3 (aq) Zn. NO 3(aq) + Ag(s) Since the positively charged ions exchanged places, and they are called cations—this is called “cationic” replacement.

But there is another way this can happen. Instead of replacing B, we replace X. A + BX BA + X A + B X Cl 2(g) + 2 Na. I(aq) 2 Na. Cl(aq) + I 2(s) Since the negative ions---called anions have switched places—we call this anionic replacement.

Double Replacement Reactions In double replacement reactions, the positive ions of two reacting ionic compounds exchange. R+ S - + T + U- R + U- + T + S - So, the cations exchanged positions, resulting in two new compounds. Ex: K 2 CO 3(aq) + Ba. Cl 2 1 Notice that you can keep track if you circle them or number them 2 3 2 KCl + Ba. CO 3 4 Notice that 1 is now with 4, and 3 is with 2.

Combustion—generally, an element or compound reacts rapidly with oxygen. For regents chemistry, it is usually a reaction of oxygen with fuels such as hydrocarbons, which are compounds of carbon and hydrogen. Ex: C 6 H 6 + O 2 CO 2 + H 2 O CH 4 + O 2 CO 2 + H 2 O In regents chemistry—also include the fuel hydrogen. H 2 + O 2 H 2 O

You are now at a point where you should be able to recognize what type of chemical reaction is in front of you so, Your assignment is to do just that.

Here’s some if we have time: Decomposition reactions Single replacement reactions Thermite is on that other website with all the reactions Anyone for Bill Nye?

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Homework Review An answer to how oxygen is recycled in space Molecular sieve design in a spaceship