1 / 19

Chemical Equations Review

Chemical Equations Review. CH 4 + 2 O 2 CO 2 + 2 H 2 O “ coefficients ” “ subscripts ” coefficients can be changed to achieve mass balance but subscripts are never changed to balance an equation Why?

mulan
Download Presentation

Chemical Equations Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemical Equations Review CH4 + 2O2 CO2 + 2H2O “coefficients” “subscripts” coefficientscan be changed to achieve mass balance but subscripts are never changed to balance an equation Why? Because changing a subscript changes the compound entirely!!!

  2. So how do we get subscripts? In ionic compounds you simply cross the ions charge values. Li + MgCl2 ??????? Single replacement reaction. Why? Li is a metal, Mg is a metal, Cl is a nonmetal Li+ replaces Mg2+ and combines with Cl- The products are Mg + LiCl The balanced equation will be 2 Li + MgCl2 Mg + 2 LiCl

  3. Balancing a Chemical Equation • write formula for each reactant and product on the correct side of the “reaction arrow” • count atoms of each element on both sides of arrow • start with the compound which has the most complex formula • add coefficients to chemical formulas to balance numbers of each atom • trial and error begins...

  4. What am I? Mg + HCl  MgCl2 + H2 Single replacement Na2CO3 + HCl  NaCl + H2CO3 Double replacement Cu + S Cu2S Synthesis

  5. NaCl is soluble in water. Solid NaCl dissociates into Na+ and Cl- ions in aqueous solution: NaCl(s) Na+(aq) + Cl-(aq)

  6. Pb(NO3)2 + 2NaI  PbI2 + 2NaNO3 (aq) (aq) (s) (aq) See solubility rules

  7. Solubility Rules:

  8. Net Ionic Equations Balanced Chemical Equation: Pb(NO3)2(aq) + 2NaI(aq)  PbI2(s) + 2NaNO3(aq) “Complete Ionic” Equation: Pb2+(aq) + 2NO3-(aq) + 2Na+(aq)+ 2I-(aq)  PbI2(s) + 2Na+(aq) + 2NO3-(aq) Cancel the “spectator ions” that appear on both sides of the arrow Pb2+(aq) + 2NO3-(aq) + 2Na+(aq)+ 2I-(aq)  PbI2(s) + 2Na+(aq) + 2NO3-(aq) “Net Ionic” Equation: Pb2+(aq) + 2I-(aq)  PbI2(s)

  9. For the exam: know how to use solubility rules to predict whether an ionic compound is insoluble or not

  10. Net Ionic Equations Revisited: • Write the (balanced!) molecular equation first • Reaction products: swap cations and anions • Predict solubility (using Solubility rules) • Write the complete ionic equation next • (s) compounds don’t ionize • (aq) compounds do ionize • ion subscripts in the molecular equation become coefficients in the complete ionic equation! • Write the netionic equation next • cancel spectator ions • The net ionic equation is a “simplified” form • of the complete ionic equation

  11. Example: Problem Ba(NO3)2 + NiSO4 Balanced Molecular Equation:

  12. Example: Problem Ba(NO3)2 + NiSO4 Ni(NO3)2 + BaSO4 Balanced Molecular Equation:

  13. Example: Problem Ba(NO3)2(aq)+ NiSO4(aq) Ni(NO3)2(aq)+ BaSO4(s) Balanced Molecular Equation:

  14. Example: Problem Ba(NO3)2(aq)+ NiSO4(aq) Ni(NO3)2(aq)+ BaSO4(s) Ba2+(aq) + 2NO3-(aq) + Ni2+(aq) +SO42-(aq) Ni2+(aq) + 2NO3-(aq) + BaSO4 (s) Balanced Molecular Equation: Complete Ionic Equation:

  15. Example: Problem Ba(NO3)2(aq)+ NiSO4(aq) Ni(NO3)2(aq)+ BaSO4(s) Ba2+(aq) + 2NO3-(aq) + Ni2+(aq) +SO42-(aq) Ni2+(aq) + 2NO3-(aq) + BaSO4 (s) Balanced Molecular Equation: Complete Ionic Equation:

  16. Example: Problem Ba(NO3)2(aq)+ NiSO4(aq) Ni(NO3)2(aq)+ BaSO4(s) Ba2+(aq) + 2NO3-(aq) + Ni2+(aq) +SO42-(aq) Ni2+(aq) + 2NO3-(aq) + BaSO4 (s) Balanced Molecular Equation: Complete Ionic Equation: Net Ionic Equation: Ba2+(aq) + SO42-(aq) BaSO4 (s)

  17. What is the Net Ionic Equation for the reaction: HCl(aq) + NaOH(aq) ?

  18. HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq) H+(aq) + -OH(aq) H2O(l)

More Related