Chemistry 104 Laboratory
	This Week
Answer Keys Gen Chem Lab Periodic Table	· Expt 1: Brita, Scum, and Scale (Week 2) o Complete Parts B, C, D with your group · Report o Procedure for B, C, D due today o Data for B, C, D.1 (Excel spreadsheet, log sheet) due today o Week 2 Worksheet with Part B Excel graphs due in two days
	Next Time
	· Expt 1: Brita (Week 3) o Thermodynamics of a Rubber Band · Quiz 3: Expt 4
	Notes for Today
	The Brita Filtration Process Cation exchange on the filter: 2(R-SO3^-)(resin cation)^+(s) + M^2+(aq) --> (R-SO3^-)2 M^2+(s) + 2(resin cation)^+ (aq) Questions We Want To Answer About Brita Water Softening Is the Brita filter effective in softening tap water (removing Ca^2+, Mg^2+)? Does the softening capacity change over time? What is the cation exchange chemistry? What are the resin cations? To Answer These Questions You Must Identify the cations present in unfiltered tap water Identify the cations left in the water after Brita filtration Identify any cation concentration changes caused by filtration Analytical Tools For The Job EDTA (Y^4-) Titration M^2+(aq) + Y^4-(aq) --> MY^2-(aq) Used to measure [M^2+] in unfiltered water Endpoint detection by spectrophotometry What information is used to calculate [M^2+]? pH Measurement Use to decide if H^+ is a resin cation Is more H^+ present after filtration than before? Review: The pH Meter Ion Chromatography Use to measure [M^2+] in unfiltered tap water Same result as EDTA Titration? Use to measure [M^2+] in filtered tap water Is Brita filter effective in softening water (removing M^2+)? Use to identify resin cation(s)in filtered water Use to measure [resin cation] in filtered water