GCSE Combined Science (AQA)

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Advanced Chemical Equations

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Atomic structure and the periodic table A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

Advanced Chemical Equations

7:14 Chemical Reactions and Equations
Spec 4.1.1.1 4.3.1.1
Previous Balanced Chemical Equations Next Mixtures
  • Extra care is needed when balancing complicated equations.
  • Balancing equations is an essential skill for exams and should be practiced.
  • The video explains balancing the equation where carbon dioxide and water produce glucose and oxygen, a photosynthesis reaction.
  • To balance the equation, the same number of each type of atom is needed on each side.
  • Keeping track of atom numbers in a table is good practice.
  • Oxygen atoms in each molecule can make balancing tricky.
  • Step 1: Count the number of atoms of each element on each side of the equation.
  • Reactants: 1 carbon, 3 oxygens, 2 hydrogens.
  • Products: 6 carbons, 8 oxygens, 12 hydrogens.
  • The equation is not balanced initially.
  • Step 2: Balance elements that appear once on each side.
  • Carbon atoms appear once on each side; balance by adding a multiplier to carbon dioxide.
  • Update the table for changes in carbon and oxygen numbers.
  • Step 3: Identify elements that still need balancing.
  • Balance hydrogen by adding a multiplier to water.
  • Update the table for changes in hydrogen and oxygen numbers.
  • Step 4: Balance remaining elements using trial and error.
  • Change the number of oxygen molecules to balance oxygen without affecting carbon and hydrogen.
  • Calculate the needed number of oxygen molecules.
  • Step 5: Recount to check numbers are balanced.
  • Double-check the equation is balanced after solving.
  • Successfully balanced the equation with 6 carbon, 18 oxygen, and 12 hydrogen atoms on both sides.

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