Wednesday Bellwork How many atoms are in each of the following compounds? –H 2 SO 4 –Ca(NO 3 ) 2 –(NH 4 ) 3 PO 4 –C 6 H 12 O 6 –2 H 2 O –10 CO 2 7 atoms! 9 atoms! 20 atoms! 24 atoms! 6 atoms! 30 atoms!

CHEMICAL REACTIONS

8.1 Chemical reaction- the changing of substances by the breaking of bonds in reactants and the formation of bonds in products.

Evidence of a chemical reaction: 1. Release of a gas Zinc is added to hydrochloric acid producing hydrogen gas and solid zinc chloride.

2. Color changes two liquids are mixed solid and a liquid mixed

3. Formation of a precipitate –a precipitate is a solid product formed by the reaction of two aqueous solutions. –It is abbreviated ppt. Aqueous sodium iodide and aqueous lead (II) nitrate produce solid lead (II) iodide and aqueous sodium nitrate.

4. Changes in heat and light –all reactions either absorb or release energy Sodium peroxide (yellow powder) and zinc powder (gray powder in the bowl) are combined Water is then squirted in & the mixture ignites

Demo Time! Rusty, Crusty Steel Wool!

Writing Chemical Equations: reactants  products yield Na + Cl 2  NaCl EXAMPLE:

Possible symbols in chemical equations: + plus  yields (s) solid (l) liquid (g) gas (aq) aqueous  equilibrium N.R. no reaction  heat is added catalyst –  (light or heat) & catalysts are written above the yield sign

Examples: To what is the arrow pointing? H 2 O 2 (aq) H 2 O (l) + O 2 (g) MnO 2 CaCO 3 CaO (s) + CO 2 (g)  H 2 (g) + O 2 (g)  H 2 O (g)

Writing and Balancing Chemical Equations Example: Write the equation for the formation of sodium hydroxide and hydrogen, from the reaction of sodium with water.

1.Write the formulas of all reactants to the left of the arrow and all products to the right of the arrow. Sodium + water Translate the equation and be sure the formulas are correct. Na + H 2 O  NaOH + H 2 sodium hydroxide + hydrogen

Write the equation for the formation of sodium hydroxide and hydrogen, from the reaction of sodium with water. 2.Once the formulas are correctly written, DO NOT change them. Use coefficients (numbers in front of the formulas), to balance the equation. DO NOT CHANGE THE SUBSCRIPTS! _____Na + _____H 2 O  ____NaOH + _____H 2

3.Begin balancing with an element that occurs only once on each side of the arrow. Ex: Na _____Na + _____H 2 O  ____NaOH + _____H 2 Na H O Na H O When you are finished, you should have equal numbers of each element on either side of the equation

4.To determine the number of atoms of a given element in one term of the equation, multiply the coefficient by the subscript of the element. Ex: In the previous equation (below), how many hydrogen atoms are there? 4 ____Na + _____H 2 O  ____NaOH + _____H 2 222

Balance elements one at a time. Balance polyatomic ions that appear on both sides of the equation as single units. (Ex: Count sulfate ions, not sulfur and oxygen separately) Balance H and O last. Save the one that is in the most places for last… Use Pencil! (NH 4 ) 2 SO 4 (aq) + BaCl 2 (aq)  BaSO 4 (s) + NH 4 Cl (aq)

Practice: Balance the equation for the formation of magnesium nitride from its elements. ____Mg + ____N 2  Mg 2+ N 3- Mg 3 N 2 3 ____Mg 3 N 2

Balance the reaction of sodium metal with chlorine gas to form sodium chloride. ____Na + ____Cl 2  NaCl Cl - Na + 22 ____NaCl

Coefficients are always whole numbers: Sometimes though, fractions seem necessary.

Ex:NH 3 + O 2  NO 2 + H 2 O H can be balanced by placing a 2 in front of NH 3 and a 3 in front of H 2 O. Then put a 2 in front of NO 2 for nitrogen to balance. _____NH 3 + _____O 2  ____NO 2 + ____H 2 O 232

Now all that is left to balance is the oxygen. There are 2 O on the reactant side and 7 on the product side. Our only source of oxygen is the O 2. Any whole number we place in front of the O 2 will result in an even number of atoms. The only way to balance the equation is to use a coefficient of 7/2. _____NH 3 + _____O 2  ____NO 2 + ____H 2 O 2327/2

On a molecular level this makes no sense. You cannot have ½ of an O 2 molecule. So…to get rid of the fraction, multiply all the coefficients by 2 (the denominator). _____NH 3 + _____O 2  ____NO 2 + ____H 2 O 2327/2 ____NH 3 + _____O 2  ____NO 2 + ____H 2 O 2327/2 () 2 = _____NH 3 + _____O 2  ____NO 2 + ____H 2 O 4647

____H 2 + ____O 2  ____H 2 O ___NH 3 + ____O 2  ____NO 2 + ____H 2 O ___Ca + ___H 2 O  ___Ca(OH) 2 + ___H 2

__NH 4 Cl +__Ca(OH) 2  __NH 3 + __H 2 O+__CaCl 2 ___ZnO + ___HCl  ___ZnCl 2 + ___H 2 O ____K + _____F 2  _____KF ____C 2 H 4 + ____O 2  ____CO 2 + ____H 2 O

Thursday Bellwork Balance the following equations. ___Zn + ___HCl  ___ZnCl 2 + ___H 2 __ Al 2 (SO 4 ) 3 + __Ca(OH) 2  __Al(OH) 3 + __CaSO 4 __K + __H 2 O  __KOH + __H 2 __CH 4 + __O 2  __CO 2 + __H 2 O

Synthesis reaction (combination reaction)- the combination of two or more substances to form a compound Elem. or cmpd. + elem. or cmpd  cmpd. General form A + B  AB The product in a reaction will have different properties from either of the reactants that formed it.

EXAMPLES: _____Na + _____Cl 2  _____Fe + _____O 2  _____Al + _____Cl 2  _____H 2 O + _____CO 2  ____NaCl ____Fe 2 O 3 H 2 CO 3 ____AlCl

Decomposition Reaction: is the breakdown of one substance into two or more other substances compound  two or more elements AB  A + B

____H 2 CO 3  ____H 2 O + ____CO 2 _____KCl  _____HCl  ____K + ____Cl 2 ____H + ____Cl

Friday Bellwork Predict the products of the following reactions and balance the equation. – Ca + N 2  – Cl 2 + Fe (iron III)  – MgO + CO 2  – Mg 3 N 2  – Li 3 N  – H 2 CO 3 

Single Replacement Reaction: One element replaces another element in a compound. element + compound  element + compound A + BC  AC + B

___Zn + ___HCl  ___Cl 2 + ___KI  ___ZnCl 2 + ___H 2 ___KCl + ___I

To determine if a single replacement reaction will take place you must compare the activities of the elements involved. For metals, use the Activity Series (pg. 217). A metal will replace any metal below it on the activity series.

Activity Series of Metals and Halogens MetalsHalogens Deceasing activity LithiumFluorine PotassiumChlorine CalciumBromine SodiumIodine Magnesium Aluminum Zinc Chromium Iron Nickel Tin Lead HYDROGEN Copper Mercury Silver Platinum Gold Will Na replace Cr in a single replacement reaction? Yes!

Practice: ___I 2 + ___NaCl  ___AgNO 3 + ___Mg  ___KBr + ___F 2  ___Mg(NO 3 ) 2 + ____Cu  N.R. ___Mg(NO 3 ) 2 + ___Ag ___KF + ___Br 2 N.R Activity Series of Metals Lithium Potassium Barium Calcium Sodium Magnesium Aluminum Zinc Iron Cadmium Nickel Tin Lead Hydrogen (a nonmetal) Copper Mercury Silver Gold Platinum Metals from Li to Na will replace H from water and acids; metals from Mg to Pb will replace H from acids only. Decreasing Activity

Double Replacement Reaction: Two elements replace each other in compounds. AB + CD  AD + CB MgCO 3 + 2HCl  MgCl 2 + H 2 CO 3 AgNO 3 + NaCl  AgCl + NaNO 3

In order for double replacement reaction to take place, one of the products must be an insoluble solid (ppt), a gas, or a molecular compound (like H 2 O). Solubility rules on pg 227 list common insoluble substances.

Negative IonPlusPositive IonForm a Compound Which is: Any negative ion+Alkali metal ions (Li +, Na +, K +, Rb +, Cs + ) Soluble Any negative ion+Ammonium ionSoluble Nitrate+Any positive ionSoluble Acetate+Any positive ion Ag + Soluble Not soluble Chloride, Bromide, or Iodide +Ag +, Pb 2+, Hg 2 2+, Cu + Any other positive ion Not soluble Soluble Sulfate+Ca 2+, Sr 2+, Ba 2+, Ra 2+, Ag +, Pb 2+ Any other positive ion Not soluble Soluble Sulfide+Alkali ions or Ammonium, Be, Mg, Ca, Sr, Ba, Ra, Any other positive ion Soluble Not soluble Hydroxide+Alkali ions or Ammonium Any other positive ion Soluble Not soluble Phosphate, Carbonate, or Sulfite +Alkali ions or Ammonium Any other positive ion Soluble Not soluble

The Solubility Song! To the tune of “ My Favorite Things” from “The Sound of Music” Nitrates and Group One and Ammonium, These are all soluble, a rule of thumb. Then you have chlorides, they’re soluble fun, All except Silver, Lead, Mercury I. Then you have sulfates, except for these three: Barium, Calcium and Lead, you see. Worry not only few left to go still. We will do fine on this test. Yes, we will! Then you have the--- Insolubles Hydroxide, Sulfide and Carbonate and Phosphate, And all of these can be dried!

CompoundPrecipitate Formed? BaSO 4 _______ Pb(NO 3 ) 2 _______ Ag 2 S_______ PbCl 2 _______ NH 4 Cl_______ Cr PO 4 _______ Yes No Yes No

__Na 2 SO 4 + __Ba(NO 3 ) 2  __NaOH + __Fe(NO 3 ) 3  __NaNO 3 + __Fe(OH) 3 __NaNO 3 + __BaSO Na + NO 3 - NaNO 3 Ba 2+ SO 4 2- BaSO 4 Na + NO 3 - NaNO 3 Fe 3+ OH - Fe(OH) 3

Bellwork Write the products of the following reactions. Balance the equation when you are done. Ni(s) + MgSO 4 (aq)  Br 2 (l) + CaCl 2 (aq)  zinc + copper(II) nitrate 

An exothermic reaction in which a substance combines with oxygen forming products in which all elements are combined with oxygen. (Burning) Energy is usually released in the form of heat and light. General form for combustion of a hydrocarbon: C x H y + O 2  CO 2 + H 2 O

Examples ____C 3 H 8 + ____O 2  ____C 6 H 12 O 6 + ____O 2  ____Mg + ____O 2  ____CO 2 + ____H 2 O ____CO 2 + ____H 2 O ____MgO

Tuesday Bellwork Write the type of reaction on the left and complete and balance the equation on the right. TypeEquation ____Li + O 2  ____Cl 2 + MgF 2  ____C 5 H 12 + O 2  ____MgCO 3  ____AgNO 3 + NaCl 

Monday Bellwork Convert the following word equations into formulas, complete the equation, and balance. –Copper (II) sulfide is added to barium hydroxide –Ethanol (C 2 H 5 OH) is burned in oxygen –Magnesium metal is added to nitrogen gas –Magnesium carbonate is heated

Quiz Information Negative IonPlusPositive IonForm a Compound Which is: Any negative ion+Alkali metal ions (Li +, Na +, K +, Rb +, Cs + )Soluble Any negative ion+Ammonium ionSoluble Nitrate+Any positive ionSoluble Acetate+Any positive ion Ag + Soluble Not soluble Chloride, Bromide, or Iodide +Ag +, Pb 2+, Hg 2 2+, Cu + Any other positive ion Not soluble Soluble Sulfate+Ca 2+, Sr 2+, Ba 2+, Ra 2+, Ag +, Pb 2+ Any other positive ion Not soluble Soluble Sulfide+Alkali ions or Ammonium, Be, Mg, Ca, Sr, Ba, Ra, Any other positive ion Soluble Not soluble Hydroxide+Alkali ions or Ammonium Any other positive ion Soluble Not soluble Phosphate, Carbonate, or Sulfite +Alkali ions or Ammonium Any other positive ion Soluble Not soluble

Quiz Information MetalsHalogens Deceasing activity LithiumFluorine PotassiumChlorine CalciumBromine SodiumIodine Magnesium Aluminum Zinc Chromium Iron Nickel Tin Lead HYDROGEN Copper Mercury Silver Platinum Gold