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Precipitation Reactions. Write Precipitation Reactions and use Solubility Rules to determine precipitate Write net ionic equations Use principles of solubility to determine water quality!. Review of Solubility!.
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Precipitation Reactions Write Precipitation Reactions and use Solubility Rules to determine precipitate Write net ionic equations Use principles of solubility to determine water quality!
Review of Solubility! • Soluble means: Ionic compound dissociates in solution. (when we are talking about aqueous the solution is water!) • Symbol: (aq) • Insoluble means: • Does not dissociates in solution.. • Another way to describe an insoluble compound is a precipitate!!! • Symbol: (s)
Write the complete equation for: • Silver nitrate and sodium carbonate react to form silver carbonate and sodium nitrate:
Why are precipitation reactions useful to understand? • Many types of ions contaminate our water and we can’t see them! (Pb2+, Hg2+) • By combining water samples with aqueous compounds, we can look for precipitates and determine what types of ions might be present in the water!!!
Ways to write precipitation reactions! • Complete molecular: shows the entire precipitation reaction and indicates the precipitate: AB + CD AD + BC • Complete ion: shows how each compound separates into its individual ions: • A+ + B- + C+ + D- AD(s) + C+ + B- • Net ionic: crosses out spectator ions and only shows ions that form the precipitate: • A+ + D- AD(s)
Spectator Ions • Ions on both sides of the complete ionic equation. They can be cancelled out as they are not directly involved in forming the precipitate!
It gets a little tricky! • You must show numbers of each type of ion. • In compounds, numbers are indicated 2 ways! • Coefficients in front of the compound • Subscripts after the element. • When writing ions, the number must always be a coefficient.
Let’s Practice: • We will write the complete molecular (already done), complete ionic, and net ionic equations for #3-7 on your solubility rules worksheet. • HW: Write the complete molecular (on a separate piece of paper), complete ionic, and net ionic equations for #2 (a-e) on the 15-1 side of your worksheet!!!