 Write the formula from the following names: ◦ Magnesium chloride ◦ Manganese (II) fluoride ◦ Sodium sulfate ◦ Lithium hydroxide ◦ Sulfur hexachloride ◦ Lead (IV) oxide

Reactions, Day 1 Whitaker 27 October 2014

 The process of how a chemical change occurs can be described by a chemical equation.  Chemical change results in a change in the chemical composition of a substance.

 General Form: ◦ Reactants  Products ◦ Reactants: what you start with. ◦ Products: what you end with.

SymbolMeaning +Plus or reacts with  Yields or produces (s)Solid (l)Liquid (g)Gas (aq)Aqueous or dissolved in water

 H 2(g) + O 2(g)  H 2 O (l)  What are the Reactants?  What are the Products?

 1 st law of conservation of matter states that matter cannot be created or destroyed, only changed.  H 2 + O 2  H 2 O

 There must be equal amounts of each element on both sides of the equation.  Number of atoms are conserved, so mass is conserved.

 Coefficients are the large numbers in front of a compound showing how many of that compounds are needed for the reaction to occur. ◦ No coefficient mean that there is only one.  Add only coefficients to change numbers. Never change the subscripts after a formula is written!!!

Fix only one element at a time. Start with whichever comes first. If an element is in two places on either side of the equation, save it for last. Always, go back and recount! You might have to change something after you’ve already fixed it.

 N 2 + H 2  NH 3  Zn + HCl  ZnCl 2 + H 2

 N 2 + 3H 2  2NH 3  Zn + HCl  ZnCl 2 + H 2

 N 2 + 3H 2  2NH 3  Zn + 2HCl  ZnCl 2 + H 2

 Na 2 CO 3 + HCl  NaCl + H 2 O + CO 2

 Na 2 CO 3 + 2HCl  2NaCl + H 2 O + CO 2

 Na (s) + H 2 O (l)  NaOH (aq) + H 2 (g)

 2Na (s) + 2H 2 O (l)  2NaOH (aq) + H 2 (g)

 S 8 (s) + O 2 (g)  SO 3 (g)

 S 8 (s) + 12O 2 (g)  8 SO 3 (g)

 Make sure you swap and drop your ionic charges  You have to go from the name to the formula!

◦ Never exist as just one atom but must be bonded to another ◦ If there’s no other atom around, they will just bond to another of the same atom

 Aqueous sodium nitride and chlorine gas combine to form aqueous sodium chloride and nitrogen gas.

 Balance the following  1. ____ Cu(s) + ____ O 2 (g) → ____ CuO(s)  2. ____ H 2 O(l) → ____ H 2 (g) + ____ O 2 (g)  3.__ Fe(s) + __ H 2 O(g) → __ H 2 (g) + __ Fe 3 O 4 (s)  4.____ AsCl 3 + ____ H 2 S → ____ As 2 S 3 + ____ HCl

 Balance the following  1. 2 Cu(s) + ____ O 2 (g) → 2 CuO(s)  2. ____ H 2 O(l) → ____ H 2 (g) + ____ O 2 (g)  3.__ Fe(s) + __ H 2 O(g) → __ H 2 (g) + __ Fe 3 O 4 (s)  4.____ AsCl 3 + ____ H 2 S → ____ As 2 S 3 + ____ HCl

 Balance the following  1. 2 Cu(s) + ____ O 2 (g) → 2 CuO(s)  2. 2 H 2 O(l) → 2 H 2 (g) + ____ O 2 (g)  3.__ Fe(s) + __ H 2 O(g) → __ H 2 (g) + __ Fe 3 O 4 (s)  4.____ AsCl 3 + ____ H 2 S → ____ As 2 S 3 + ____ HCl

 Balance the following  1. 2 Cu(s) + ____ O 2 (g) → 2 CuO(s)  2. 2 H 2 O(l) → 2 H 2 (g) + ____ O 2 (g)  3.3 Fe(s) + 4 H 2 O(g) → 4 H 2 (g) + __ Fe 3 O 4 (s)  4.____ AsCl 3 + ____ H 2 S → ____ As 2 S 3 + ____ HCl

 Balance the following  1. 2 Cu(s) + ____ O 2 (g) → 2 CuO(s)  2. 2 H 2 O(l) → 2 H 2 (g) + ____ O 2 (g)  3.3 Fe(s) + 4 H 2 O(g) → 4 H 2 (g) + __ Fe 3 O 4 (s)  4.2 AsCl H 2 S → ____ As 2 S HCl