POD Write the chemical equations for the following 1.Hydrogen gas reacts with oxygen gas to form water 2.Nitrogen gas mixes with hydrogen gas to form ammonia 3.Iron reacts with water to form iron(IV)oxide and hydrogen gas 2H 2 (g) + O 2 (g)  2H 2 O(l) N 2 (g) + 3H 2 (g)  2NH 3 (l) Fe(s) + 2H 2 O(l)  FeO 2 (s) + 2H 2 (g)

Avogadro’s #, Moles, & Molar Mass

Moles  particles (multiply by Avogadro’s #) How many atoms are in 2 mol Zn? 2 mol (6.02E23 atoms / 1 mol) = 1.2E24 atoms Particles  moles (divide by Avogadro’s #) How many moles are in 7.99E23 molecules of sugar? 7.99E23 molecules (1 mol / 6.02E23 molecules) =1.3 mol

Moles  grams (multiply by molar mass) How many grams is 2 moles of O 2 ? First find molar mass of O 2 =31.98g/mol 2 mole O 2 (31.98g / 1 mol) = g Grams  moles (divide by molar mass) How many moles is g barium iodide? First find molar mass of BaI 2 =391.13g/mol g (1 mol / g) = 0.5 mol

Chemical Reactions The process by which the atoms of one or more substances are rearranged to form different substances Evidence of a chemical reaction: ‒Color change ‒Temperature change ‒Odor ‒Gas bubbles ‒Formation of a solid (precipitate)

Balancing chemical equations To balance a chemical equation you must use a coefficient (a # that goes before the reactant or product) Always whole #’s Not balanced Al(s) + Br 2 (l)  AlBr 3 (s) Balanced 2Al(s) + 3Br 2 (l)  2AlBr 3 (s)

Steps to Balance Chemical Equations 1.Write the skeleton equation for the reaction. Make sure your chemical formulas are correct 2.Count the atoms of elements in the reaction

Steps to Balance Chemical Equations 3. Change the coefficients to make the number of atoms of each element equal on both sides of the equation. NEVER change a subscript 4. Write coefficients in their lowest possible ratio.

Steps to Balance Chemical Equations 5. Check your work

2NaOH + CaBr 2  Ca(OH) 2 + 2NaBr

Classifying Chemical Reactions Synthesis Combustion Decomposition Replacement Neutralization

Classifying Chemical Reactions Synthesis – Two or more substances react to form a single product Combustion – Oxygen combines with a substance and releases energy in the form of heat & light Decomposition – A single compound breaks down into two or more elements or new compounds (opposite of synthesis) Replacement – Involves the replacement of an atom in a compound, can be single or double replacement (think switching partners) Neutralization – A reaction in which an acid and a base in an aqueous solution react to produce a salt and water

Classifying Chemical Reactions Synthesis – Two or more substances react to form a single product A + B  AB A + B + C  ABC CaO(s) + H 2 O(l)  Ca(OH) 2 (s) 2SO 2 (g) + O 2 (g)  2SO 3 (g)

Classifying Chemical Reactions Combustion – Oxygen combines with a substance and releases energy in the form of heat & light Most common form of power plant in the US is coal plant C(s) + O 2 (g)  CO 2 (g) CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2 H 2 O(g)

14. Al(s) + S(s)  Al 2 S 3 (s) synthesis 16. NO 2 (g) + O 2 (g)  N 2 O 5 (g) combustion, synthesis 15. H 2 O(l) + N 2 O 5 (g)  HNO 3 (aq) synthesis

Classifying Chemical Reactions Decomposition – A single compound breaks down into two or more elements or new compounds (opposite of synthesis) AB  A + B Usually require an energy source (such as heat, light, or electricity) to occur NH 4 NO 3 (s)  N 2 O(g) + 2H 2 O(g)

Classifying Chemical Reactions Decomposition – A single compound breaks down into two or more elements or new compounds (opposite of synthesis) 2NaN 3 (s)  2Na(s) + 3N 2 (g)

18. 2Al 2 O 3 (s)  4Al(s) + 3O 2 (g) 19. Ni(OH) 2 (s)  NiO(s) + H 2 O(l) 20. NaHCO 3 (s)  Na 2 CO 3 (aq) + H 2 O(l)

Classifying Chemical Reactions Single Replacement – Involves the replacement of an atom in a compound, (think switching partners)

Classifying Chemical Reactions Single Replacement – Involves the replacement of an atom in a compound, (think switching partners) A + BX  AX + B 2Li(s) + 2HOH(l)  2LiOH(aq) + H 2 (g) F 2 (g) + 2NaBr(aq)  2NaF(aq) + Br 2 (l)

a)Fe(s) + CuSO 4 (aq)  FeSO 4 (aq) + Cu(s) b) 3Mg(s) + 2AlCl 3 (aq)  2Al(s) + 3MgCl 2 (aq) c) 2K(s) + ZnCl 2 (aq)  Zn(s) + 2KCl(aq) challenge) 2Al(s) + 3Pb(NO 3 ) 2 (s)  3Pb(s) + 2Al(NO 3 ) 3 (aq)

Classifying Chemical Reactions Double Replacement – Involves the exchange of ions between two compounds (think switching partners)

Classifying Chemical Reactions Double Replacement – Involves the exchange of ions between two compounds (think switching partners) AX + BY  AY + BX Ca(OH) 2 (aq) + 2HCl(aq)  CaCl 2 (aq) + 2HOH(l) 2NaOH(aq) + CuCl 2 (aq)  2NaCl(aq) + Cu(OH) 2 (s)

Writing Double Replacement Reactions