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Cl 2 2Cl 2Cl 2 Purpose: Students will be able to balance chemical equations. Warm-up: Whats the difference between the three formulas below? one moleculetwo.

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Presentation on theme: "Cl 2 2Cl 2Cl 2 Purpose: Students will be able to balance chemical equations. Warm-up: Whats the difference between the three formulas below? one moleculetwo."— Presentation transcript:

1 Cl 2 2Cl 2Cl 2 Purpose: Students will be able to balance chemical equations. Warm-up: Whats the difference between the three formulas below? one moleculetwo atomstwo molecules

2 Molecules may also have brackets to indicate numbers of atoms. E.g. Ca(OH) 2 Notice that the OH is a group The 2 refers to both H and O O H O H Ca How many of each atom are in the following? a) NaOH b) Ca(OH) 2 c) 3Ca(OH) 2 Na = 1, O = 1, H = 1 Ca = 1, O = 2, H = 2 Ca = 3, O = 6, H = 6 Counting Atoms

3 Balancing Equations: MgO Law of Conservation of Mass: matter can neither be created or destroyed Since atoms cannot be created or destroyed, they are only rearranged in a chemical reaction The number of atoms must be the same on both sides!

4 Example: Magnesium + Oxygen Mg + O2 MgO However, this is not balanced Left: Mg = 1, O = 2 Right: Mg = 1, O = 1 O MgO + MgO Balancing Equations: MgO

5 However, this is not balanced Left: Mg = 1, O = 2 Right: Mg = 1, O = 1 O MgO + MgO Balancing Equations: MgO From: Mg + O2 MgO 2Mg + O2 2MgO is correct Mg + ½O2 MgO is incorrect Mg2+ O2 2MgO is incorrect 4Mg + 2O2 4MgO is incorrect

6 Balance Equations 5 233.5 2746 222 263 e) C 2 H 6 + O 2 CO 2 + H 2 O a) P 4 + O 2 P 4 O 10 b) Li + H 2 O H 2 + LiOH c) Bi(NO 3 ) 3 + K 2 S Bi 2 S 3 + KNO 3 d) C 2 H 6 + O 2 CO 2 + H 2 O

7 a)Mg + 2HCl MgCl 2 + H 2 b)3Ca + N 2 Ca 3 N 2 c)NH 4 NO 3 N 2 O + 2H 2 O d)2BiCl 3 + 3H 2 S Bi 2 S 3 + 6HCl e)2C 4 H 10 + 13O 2 8CO 2 + 10H 2 O f)6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O g)3NO 2 + H 2 O 2HNO 3 + NO h)Cr 2 (SO 4 ) 3 + 6NaOH 2Cr(OH) 3 + 3Na 2 SO 4 i)Al 4 C 3 + 12H 2 O 3CH 4 + 4Al(OH) 3 Balance these skeleton equations:

8 a)2KNO 3 2KNO 2 + O 2 b)2Pb(NO 3 ) 2 2PbO + 4NO 2 + O 2 c)P 4 + 6I 2 4PI 3 d)3MgO + 2H 3 PO 4 Mg 3 (PO 4 ) 2 + 3H 2 O e)Br 2 + 2KI I 2 + 2KBr f)Ca(OH) 2 + 2HNO 3 Ca(NO 3 ) 2 + 2H 2 O g) Bi 2 O 3 + 3H 2 2Bi + 3H 2 O h)3Fe + 2O 2 Fe 3 O 4 i)2CaO + 5C 2CaC 2 + CO 2 Here are some more to balance:


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