Chemical Reactions Part II Chemistry 1

Check for Understanding Balance the following Chemical Equations:  CH 4 + O 2  CO 2 + H 2 O  Na 2 O 2 + H 2 SO4  Na 2 SO 4 + H2O2  N 2 + H 2  NH 3  When solid copper reacts with aqueous silver nitrate, the products are aqueous copper (II) nitrate and silver metal.

Review Individual Practice

Steps to Follow to Balance Equations 1. Determine the number of atoms for each element. 2. Pick an element that is not equal on both sides of the equation. 3. Add a coefficient in front of the formula with that element and adjust your counts. 4. Continue adding coefficients to get the same number of atoms of each element on each side. **Note: LEAVE THE SUBSCRIPTS ALONE! (you cannot change the chemical formula to balance atoms)

Steps to Write Equations 1. When writing formulas don’t forget to look up charges if the compound is ionic!!! 2. Diatomic Molecules: Always travel in pairs 1. H.O.F.Br.I.N.Cl. (Dr. HOFINBrCl) 2. These elements need a subscript 2 after them if they are by themselves! 3. Once the equation is written, then balance the equation by adding coefficients.

Individual Practice Word problems:  When sodium metal reacts with iron (II) chloride, iron metal and sodium chloride are formed.  When dissolved beryllium chloride reacts with dissolved silver nitrate in water, aqueous beryllium nitrate and silver chloride powder are made. (include state)  On your homework from today write the names of the products and reactants for 1-6.

Types of Chemical Reactions

Types of Reactions DEMO Activity  LAB Pictures  Keys to success-  Be sure your hand is VERY soapy!!  Keep your hand flat  Keep all your fingers together and “tuck your thumb in”  Do NOT move your hand once it is on fire.  Do not forget to SMILE for your picture!

Synthesis Reaction Synthesis Reaction: A reaction in which two or more substances combine to form a new compound. A + B AB

Examples of Synthesis Rxn A + B AB Water: H 2 + O 2 H 2 O Table Salt: Na + Cl 2 NaCl Given the following reactants, predict the products. S 8 + O 2

Synthesis: 2Mg + O 2 → 2MgO

Decomposition Reactions Decomposition Reaction: A reaction in which a single compound breaks down to form two or more simpler substances. AB A + B

Examples of Decomposition Rxn Digestion is a series of decomposition reactions that break down food for fuel for your body. The production of gasoline is done by “cracking” crude oil where you break down carbon and hydrogen molecules. Electrolysis of water: H 2 OH 2 + O 2

Decomposition: C 12 H 22 O 11 → 12C + 11H 2 O

Combustion Reactions Combustion Reactions: A reaction where an organic molecule is combined with oxygen. C x H y + O 2 CO 2 + H 2 O  Oxygen (O 2 ) is a reactant.  CO 2 and H 2 O are produced

Uses for Combustion Combustion reactions are used in your home everyday in stoves, water heaters, and furnaces. Example of Combustion Reaction: 2CH 4 + 4O 2 2CO 2 + 4H 2 O

Combustion: CH 4 + 2O 2 → CO 2 + 2H 2 O

Single Displacement Reaction Single Displacement Reaction: A reaction in which one element takes the place of another element in a compound. * A more reactive element will take the place of a less reactive element. (see page 286 Table 3) AX + B BX + A

Examples of Single Displacement Zn + HCl ZnCl 2 + H 2 Q: In the example above, which element is more reactive? CuCl 2 + Al Q: In the above example, predict the products.

Single Replacement: Cu + 2AgNO 3 → Cu(NO 3 ) 2 + 2Ag

Double Displacement Reaction Double Displacement Reaction: A reaction where there is an apparent exchange of atoms or ions between two compounds. AX + BY AY + BX Indicators of a double displacement reaction:  Formation of a Precipitate (solid)  Formation of a Gas (bubbles)  Formation of Water

Example of Double Displacement The yellow lines on the roads are made from a double displacement reaction. Pb(NO 3 ) 2 + K 2 CrO 4 PbCrO 4 + KNO 3

Double Replacement: 3CuCl 2 + 2Na 3 PO 4 → Cu 3 (PO 4 ) 2 + 6NaCl

Practice (in your notes)  Balance and Classify the following chemical reactions:  __Mg + ___HCl ____MgCl 2 + ____H 2  __C 4 H 8 + ___ O 2 ____CO 2 + ____ H 2 O  ___Ca(OH) 2 + ___H 2 SO 4 ____CaSO 4 + ___H 2 O  ___N 2 + ___O 2 ____N 2 O 5

Individual Practice  Unit 8 Review Packet  Access Term 1 Final Exam Review Packet (blog)  Questions? (10minutes)

Chemical Equations/Reactions Exam  Friday, March 6th!  Term deadline is March 9th!

Acid-Base Reactions Acid/Base Rxn: The reactants will include an acid combining with a base. The products will include water and a salt. HX + B(OH) H 2 O + BX

Acid-Base Reactions  The Bronsted-Lowry Definitions  Acid is a proton donor.  Base is a proton acceptor.  An acid-base reaction is often called a neutralization reaction.

Examples of Acid/Base Reaction HCl + Ca(OH) 2 H 2 O + CaCl 2 HCN + K(OH)H 2 O + KCN

Oxidation Reduction (REDOX) Reactions  Reactions in which one or more electrons are transferred (redox reactions)  Example: H 2(g) + Cl 2(g) 2HCl (g) Electrons are transferred from the hydrogen to the chlorine.  Recall Rules for Assigning Oxidation States  Remember: The sum of the oxidation states in a neutral compound must equal zero.

Oxidation States  Assign oxidation states to each of the atoms in the following compounds: Hint: Check that oxidation states sum up to the charge on the compound/ion.  CaF 2  C 2 H 6  H 2 O  ICl 5  KMnO 4  SO 4 2-

Practice- Oxidation States Fe 2 O 3 + 2AlAl 2 O 3 + 2Fe THE IRON GAINED ELECTRONS. IT HAS BEEN REDUCED. THE ALUMINUM LOST ELECTRONS. IT HAS BEEN OXIDIZED. OIL – Oxidation Involves Loss (of electrons) RIG- Reduction Involves Gain (of electrons)

OIL RIG Practice  For each reaction, identify the atoms that undergo reduction or oxidation (and charges). Also, list the oxidizing and reducing agents. 2H 2(g) + O 2(g) 2H 2 O (g) Zn (s) + Cu 2+ (aq) Zn 2+ (aq) + Cu (s) 2AgCl (s) + H 2(g) 2H + (aq) + 2Ag (s) + 2Cl - (aq)