balancing equations.ppt
- 1. Reactants and Products •Reactant - The chemical(s)/element(s) you start with before the reaction occurs Think “Raw” Materials! •Written on left side of equation… •Where the “arrow” begins •Product - The new chemical(s)/elements formed by the reaction •Right side of equation… •Where the “arrow” points
- 2. Law of Conservation of Mass •In a chemical reaction, matter is neither created nor destroyed •In other words, the number and type of atoms going INTO a reaction MUST be the same as the number and type of atoms coming OUT •If an equation obeys the Law of Conservation, it is balanced. •In a chemical reaction, matter is neither created nor destroyed •In other words, the number and type of atoms going INTO a reaction MUST be the same as the number and type of atoms coming OUT •If an equation obeys the Law of Conservation, it is balanced.
- 3. How to Balance Chemical Equations
- 4. Rules for balancing a chemical equation 1. Matter cannot be created or destroyed. 2. Subscripts CANNOT be added, removed, or changed. 3. You can ONLY CHANGE coefficients.
- 5. Subscripts and Coefficients • Subscript - shows how many atoms of an element are in a molecule • EX: H2O • 2 atoms of hydrogen (H) • 1 atom of oxygen (O) • Coefficient - shows how many molecules there are of a particular chemical • EX: 3 H2O • Means there are 3 water molecules.
- 6. An Unbalanced Equation •CH4 + O2 CO2 + H2O Reactant Side Product Side 1 carbon atom 4 hydrogen atoms 2 oxygen atoms 1 carbon atom 2 hydrogen atoms 3 oxygen atoms NOT THE SAME!
- 7. A Balanced Equation CH4 + 2O2 CO2 + 2H2O Reactant Side Product Side 1 carbon atom 4 hydrogen atoms 4 oxygen atoms 1 carbon atom 4 hydrogen atoms 4 oxygen atoms BOTH ARE EQUAL!
- 8. Balancing Equations Balance the following equation by adjusting coefficients Make a “t” chart to help! reactants products N H N2 + H2 NH3 2 2 1 3 2 2 6 3 6
- 9. Balancing Equations • Balance the following equation by adjusting coefficients Try the “t” chart again! KClO3 KCl + O2 reactants products K Cl O 1 1 1 1 3 2 3 2 2 2 6 6 2 2 2
- 10. Try this, Zn + HCl ---> ZnCl2 + H2
- 11. Check your answer: Zn + 2HCl ---> ZnCl2 + H2
- 12. Try this, S8 + F2 ---> SF6
- 13. f we start by balancing the fluorine, we know that as soon as we try to balance the sulfur, we will have to alter the fluorine again. So start with the sulfur. There are eight of them on the left but only one on the right. Put an 8 in front of the SF6 S8 + F2 ---> 8SF6 And now we can see that there are 48 fluorines on the right and only two on the left, so put a 24 in front of the F2 on the left. S8 + 24F2 ---> 8SF6
- 14. C5H12 + O2 ---> CO2 + H2O
- 15. There are five carbons on the left but only one on the right, and on each side the carbon is in a single chemical species. Put a 5 in front of the CO2 on the right hand side. C5H12 + O2 ---> 5CO2 + H2O There are twelve hydrogens on the left but only two on the right hand side, and hydrogen is in a single species on each side. Put a 6 in front of the H2O on the right hand side. C5H12 + O2 ---> 5CO2 + 6H2O Finally, there are only two oxygens on the left hand side but 16 of them on the right hand side. So put a 8 in front of the O2 on the left hand side. C5H12 + 8O2 ---> 5CO2 + 6H2O It's now a balanced chemical equation.