chem161sg_chapter4

chem161sg_chapter4 - Chapter 4 Chemical Reactions in...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 4 Chemical Reactions in Aqueous Solutions Electric current: is a flow of charged particles. In metals, the conduction of electricity is accomplished by the flow of electrons. Molten (melted) ionic compounds, like Na + Cl - , (contrast with molecular compounds, like alcohol ), or aqueous solution of ionic compounds that release cations and anions in solution, also conduct electricity and the conduction is due to the flow of the ions. Michael Faraday studied the conduction of electricity in solution. Electrolyte: a substance that, when dissolved in water results in a solution that conducts electricity. Reason: electrolytic solution contains ions that are responsible for conduction of electricity. NaCl (s) Na + (aq) + Cl (aq) H 2 O N a C l ( s ) H 2 O Na + (aq) Cl (aq) Nonelectrolyte: a substance that, when dissolved in water results in a solution that does not conduct electricity. Reason: the solute molecules remain molecular (i.e. they do not dissociate into ions.) e.g. sugar (glucose, sucrose…), alcohol 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Electrolytes Weak Electrolyte: A substance that is partially ionized in solution. - weak acids - weak bases HF (aq) Æ H + (aq) + F (aq) mostly this form very little Therefore, HF in water is represented by HF (aq) Strong Electrolyte: A substance that completely ionizes in solution.( table 4.1 ) - strong acids - strong bases - ionic compounds HCl (aq) Æ H + (aq) + Cl (aq) NaOH (aq) Æ Na + (aq) + OH (aq) NaCl (aq) Æ Na + (aq) + Cl (aq) Note : Strong and weak electrolyte are terms used to indicate the extent to which a particular compound dissociates to generate ions in solution. Note: When a strong electrolyte dissolves in water to give anions and cations, the concentration of these ions can be calculated based on the stoichiometric relationship between the cation and the anion. e.g. NaCl(s) Æ Na + (aq) + Cl - (aq) , NaCl is a 1:1 salt MgCl 2 (s) Æ Mg 2+ (aq) + 2 Cl - (aq) MgCl 2 is a 1:2 salt Na 2 SO 4 (s) Æ 2 Na + (aq) + SO 4 2- (aq) Na 2 SO 4 is a 2:1 salt In NaCl, the [ Na + ] is equal to [ Cl - ] ( brackets refer to concentration) In MgCl 2 the [Cl - ] is twice the [Mg 2+ ] In Na 2 SO 4 the [Na + ] is twice the [SO 4 2- ] In calculating the concentration of a particular ion in solution, one should take into consideration the contribution to the concentration of that ion from all the sources. e.g. What is the concentration of the chloride ion when 50.0 mL of a 0.50 M NaCl is added to 100 mL of 0.20 M MgCl 2 .(assume volumes are additive) 2
Background image of page 2
Reactions to be considered: A. Acid – Base Reactions – (neutralization.) B. Precipitation Reactions – (the formation of an insoluble solid) C. Redox Reactions – (electron transfer from one specie to another) A. Acid base reactions. Recall:
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 15

chem161sg_chapter4 - Chapter 4 Chemical Reactions in...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online