Chem 209 - Study guides, Class notes & Summaries

Calculate the pH of a 0.10M HOAc (acetic acid) solution. - Answer-pH = -log(.10) = 1 Calculate the pH of each of the following solutions: a. 0.10M HCl b. 2.0x10^-4M HNO3 c. 0.015M NaOH d. 12M HCl - Answer-Use equation: pH = -log(molarity) a. 1 b. 3.7 c. 12.17 d.-1.1 Calculate the total number of moles of acid in 33.6 mL of 0.10M HCl and 0.10M H2SO4. - Answer-.00336 mol each Calculate the total number of moles of base in: a. 675 mg CaCO3 b. 135 mg Mg(OH)2 - Answer-a. 0.00674 b. 0.0...

1. Draw a block diagram of a GC instrument, labeling all the important components. - Mobile Phase Reservoir, Sample Injector, Stationary Phase, Detector, and Read-out carrier gas - mobile phase In a GC experiment, a student injects 2.0 μL of a 20% ethanol/water solution into the GC. Calculate the weight of ethanol that has been injected. (The density of ethanol is 0.789 g/mL at 20° C.) - 0.789 g/ml -> 0.789 mg/μL 20% of 2.0 = 0.4 0.4 μL x 0.789 mg/μL = 0.3156 mg In general, how w...

Calculate the absorbance A of solutions whose percent transmittance is measures as 5%, 10%, 50%, and 100%. - Answers-A=-log(T) 1.3, 1.0, .30, and 0 respectively Give the block diagram of a visible spectrophotometer, illustrating the major components of the instrument in the correct sequence. - Answers-[Light source] ---many lambdas---> [Monochromator] --- one lambda---> [Sample cell] ---I---> [Photodetector] ------> [Readout] It is important that Kf for FeSCN2+ has a large valu...

carrier gas -Answer-mobile phase In a GC experiment, a student injects 2.0 μL of a 20% ethanol/water solution into the GC. Calculate the weight of ethanol that has been injected. (The density of ethanol is 0.789 g/mL at 20° C. -Answer-0.3156 mg In general, why will an increase in operating temperature/mobile phase flow rate cause a given peak to have a longer or a shorter retention time? -Answer-faster flow through column In general, will an increase in operating temperature/mobile phase...

Chem Ch. 2 Questions and Answers 100% Pass 1. What defines ions? - A. Particles with a net electrical charge not equal to zero - B. Atoms having gained electrons - C. Atoms having lost electrons - D. All of the above Explanation: Ions are atoms or molecules that have gained or lost electrons, resulting in a net electrical charge. This definition encompasses both positively charged ions (cations) that have lost electrons and negatively charged ions (anions) that have gained electr...

What is a back titration? - ️️A titration in which a known excess of titrant is added and then the excess is carefully titrated. What is the balanced chemical equation for the complete reaction between CO3 2- and HCl? Between KHP and NaOH? SHOW THE NET IONIC EQUATIONS. - ️️2HCl(aq) + CO3 2-(aq) ---> H2O(l) + CO2(g) + 2Cl-(aq) 2H+(aq) + CO3 2-(aq) ---> H2O(l) + CO2(g) KHP(aq) + NaOH(aq) ---> NaKP(aq) + H2O(l) KHP(aq) + OH-(aq) ---> KP-(aq) + H2O(l) Calculate the total ...

What is the Bronstead-Lowry definition of an Acid? - ️️They are proton DONORS! [H+] What is the Bronstead-Lowry definition of a Base? - ️️They are proton ACCEPTORS! [H+] Example/further description of Bronstead-Lowry Acids - ️️These give AwAy protons; emphasis on the A's.... "A.P.A." Example/further description of Bronstead-Lowery Bases - ️️protons Belong to them, they Bring them in... emphasis on the B's.... "P.B.B." What is a STRONG Base and Acid? -️️These diss...

What is a back titration? - ️️A titration in which a known excess of titrant is added and then the excess is carefully titrated. What is the balanced chemical equation for the complete reaction between CO3 2- and HCl? Between KHP and NaOH? SHOW THE NET IONIC EQUATIONS. - ️️2HCl(aq) + CO3 2-(aq) ---> H2O(l) + CO2(g) + 2Cl-(aq) 2H+(aq) + CO3 2-(aq) ---> H2O(l) + CO2(g) KHP(aq) + NaOH(aq) ---> NaKP(aq) + H2O(l) KHP(aq) + OH-(aq) ---> KP-(aq) + H2O(l) Calculate the total ...

What is the balanced chemical reaction of Fe3+ with thiocyanate? -️️SCN-(aq) + Fe3+(aq) = Fe(SCN)2+(aq) Show the equation for Beer's Law and define all the terms (including units) - ️️A=Ebc A= Sample's measured absorbance E= molar absorptivity at the wavelength used (L/(mol x cm) b= width of sample (cm) c= sample concentration (M) What is the lambda max, how is it determined, and why are absorption measurements such as those in this experiment made at this lambda? - ️️Lambd...