Presentation on theme: " Mass is never created or destroyed-ALL must be conserved and accounted for during a chemical reaction The same number of atoms of reactant elements."— Presentation transcript:
Mass is never created or destroyed-ALL must be conserved and accounted for during a chemical reaction The same number of atoms of reactant elements must equal the atoms of product elements
To write a balanced chemical equation, first write the skeleton equation. Then use coefficients to balance the equation so that it obeys the law of conservation of mass. 11.1
Some elements exist naturally in pairs, as diatomic molecules. You will be expected to memorize these: Br 2, I 2, N 2, Cl 2, H 2, O 2, F 2.
Soild: (s) Examples: S (s), Na (s), Cu (s) Liquid: (l) Examples: H 2 O (l), C 4 H 10(l) Gas: (g) Examples: O 2(g), Cl 2(g), CH 4(g) Aqueous: (aq) – Dissolved in water. Examples: NaCl (aq), HF (aq), BaCl 2(aq)
There are five types of chemical reactions: 1. Synthesis reactions 2. Decomposition reactions 3. Single displacement reactions 4. Double displacement reactions 5. Combustion reactions Unit objective: identify the type of reaction and predict the product(s).
Steps for doing reaction problems: 1. Identify the type of reaction. 2. Predict the product(s) using the type of reaction as a model. 3. Check for diatomics. (BrINClHOF) 4. Balance the equation.
Synthesis reactions occur when two substances (generally elements) combine to form a compound. reactant + reactant 1 product Basically: A + B AB Example: 2H 2 + O 2 2H 2 O Example: C + O 2 CO 2
Predict the products. Write and balance the following synthesis reaction equations. Sodium metal reacts with chlorine gas Na (s) + Cl 2(g) Solid Magnesium reacts with fluorine gas Mg (s) + F 2(g) Aluminum metal reacts with fluorine gas Al (s) + F 2(g)
Decomposition reactions occur when a compound breaks up into the elements or into a few simpler compounds 1 Reactant Product + Product In general: AB A + B Example: 2 H 2 O 2H 2 + O 2 Example: 2 HgO 2Hg + O 2
Predict the products. Then, write and balance the following decomposition reaction equations: Solid Lead (IV) oxide decomposes PbO 2(s) Aluminum nitride decomposes AlN (s)
Identify the type of reaction for each of the following synthesis or decomposition reactions, and write the balanced equation: H 2(g) + O 2(g) BaCO 3(s) Zn (s) + S (s) NH 3(g) + H 2 CO 3(aq) NI 3(s)
Single Replacement Reactions occur when one element replaces another in a compound. A metal can replace a metal (+) OR a nonmetal can replace a nonmetal (-). element + compound element + compound A + BC AC + B (if A is a metal) OR A + BC BA + C (if A is a nonmetal) (remember the cation always goes first!) When H 2 O splits into ions, it splits into H + and OH - (not H+ and O -2 !!)
Example: Zn + CuCl 2 Zn Cl Cu + General: AB + C AC + B Cl Zn Cu + LIKE replaces LIKE
Activity Series lists metals in order of decreasing reactivity. As a general rule, more reactive metals replace less reactive metals in a compound Li K Ba Ca Na Mg Al Zn Fe Cd Ni Sn Pb H Cu Hg Ag Au Li K Ba Ca Na Mg Al Zn Fe Cd Ni Sn Pb H Cu Hg Ag Au
Write and balance the following single replacement reaction equation: Zinc metal reacts with aqueous hydrochloric acid: Zn (s) + HCl (aq) ZnCl 2 + H 2(g) Note: Zinc replaces the hydrogen ion in the reaction 2
Sodium chloride solid reacts with fluorine gas NaCl (s) + F 2(g) NaF (s) + Cl 2(g) Note that fluorine replaces chlorine in the compound Aluminum metal reacts with aqueous copper (II) nitrate Al (s) + Cu(NO 3 ) 2(aq) 22
Double Replacement Reactions occur when a metal replaces a metal in a compound and a nonmetal replaces a nonmetal in a compound Compound + compound compound+ compound AB + CD AD + CB
Solubility rules- The formation of a precipitate is a driving force of a double replacement reaction When you predict the products of a double replacement reaction, you must indicate which product is the precipitate using the solubility rules If both products are soluble, the reaction will not occur- all ions will remain in solution
Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO 3(aq) + NaCl (s) AgCl (s) + NaNO 3(aq) Another example: K 2 SO 4(aq) + Ba(NO 3 ) 2(aq) KNO 3(aq) + BaSO 4(s) 2
Predict the products. Balance the equation HCl (aq) + AgNO 3(aq) CaCl 2(aq) + Na 3 PO 4(aq) Pb(NO 3 ) 2(aq) + BaCl 2(aq) FeCl 3(aq) + NaOH (aq) H 2 SO 4(aq) + NaOH (aq) KOH (aq) + CuSO 4(aq)
Combustion reactions occur when a fuel reacts with oxygen gas, which produces heat! Fuel + O 2 (+ Heat) Product
Hydrocarbon Combustion: C x H y + O 2 CO 2 + H 2 O Products in combustion are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by- products like carbon monoxide) Combustion is used to heat homes (CH 4 )and run automobiles (octane: C 8 H 18 )
Edgar Allen Poe’s drooping eyes and mouth are potential signs of CO poisoning.
Example C 5 H 12 + O 2 CO 2 + H 2 O Write the products and balance the following combustion reaction: C 10 H 22 + O 2 568
State the type, predict the products, and balance the following reactions: 1. BaCl 2 + H 2 SO 4 2. C 6 H 12 + O 2 3. Zn + CuSO 4 4. Cs + Br 2 5. FeCO 3