Unit 4, Lesson 3: Writing Chemical Equations

Writing Chemical Equations Write the formula for each substance involved. Remember: 7 special elements always form diatomics (two-atom compounds) when by themselves. These are H2, N2, O2, F2, Cl2, Br2, and I2.

Writing Chemical Equations Show the phase by writing the appropriate symbol in brackets after the formula. Solid = s Liquid = l Gas = g Aqueous (meaning dissolved in water) = aq The words crystal, powder, and precipitate all indicate a solid.

Brain Break!

Examples Solid magnesium reacts with chlorine gas to produce solid magnesium chloride. (Try it!) Aqueous hydrochloric acid reacts with calcium carbonate crystals, producing aqueous calcium chloride, gaseous carbon dioxide, and liquid water. I do #1, then we do #2 – 15 min

Practice Time! Pg. 113 #57(a-d) and 58-61 Formulae of acids: phosphoric acid = H3PO4 sulphuric acid = H2SO4 hydrobromic acid = HBr 15 min