Chemistry Final Exam Questions – Flashcards
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Unlock answers| Rover Curiosity include: |
Mineral Identification camera. Chemical composition spectrometer. Weather sensors. Rock-vaporising laser and chemical identification camera. Organic compound detector. Radiation Sensor Hydrated mineral sensor. |
| EPA Lowering of arsenic levels. |
| From 50 to 10 ug/L |
| Taurine |
| Found in chocolate; Organic acid widely distributed in animal tissue. Major constituent of bile; can be found in large intestines. Function for conjugation of bile acids and antioxidizing. |
Safety Label Top Left Right Bottom |
Top(red) Fire hazard 0-4 Left (Blue): Health 0-4 Right(Yellow): Reactivity 0-4 Bottom(White): Info |
| graduated readings |
| Estimate to nearest 10th of division. I.g. 0.10ml divisions can be read 0.11ml. |
| Tolerances of class A burets. |
| [image] |
| Tolerance class A volumetric flask. |
| [image] |
1.Precision 2.Accuracy 3.Systematic Error 4.Random Error |
1. Reproducibility; how close the measurements are to each other. 2. How close the measurements are to real values. 3. Determinate error; values are either all high or all low. 4. Indeterminate error. |
| T-test |
Case 1: Compare an answer with accepted value Case 3: Testing two methods (paired t-test). Can also be used to determine if one datum is out of the norm. |
| Most common estimates of uncertainty |
1. Confidence interval 2. Standard deviation |
| Q-test |
Aka Grubbs'test. Determine if one datum point should be rejected. Gap/Range if Q is greater, than table, value can be rejected. |
| Least Square |
| Means to evaluate calibration curves. |
| Calibration curves error of y vs x |
| y value errors are greater than x value errors. |
| Single blind studies |
| Use samples identified the lab as performance evaluation studies. |
| Double blind studies |
| Use standards, but the measurer doesn't know that. |
| Control chart |
| Visual representation of confidence intervals for a Gaussian distribution. Warns observer whether values stray dangerously from the standard. |
| Observation on a control chart that requires troubleshooting. |
1 observation beyond the action lines 2 to 3 consecutive measurements between warning and action lines. 6 consecutive all increasing or all decreasing measurements. 7 consecutive measurements all above or all below the center line 14 consecutive points alterning up and down An obvious nonrandom pattern |
| Quality assurance process |
Use objectives Specifications Assessment |
| Method validation |
| Methods proving that a process is valid. |
| Specificity |
| How good he instrument is at seperating the intended analyte from other stuff. |
| Linearity |
| How well the curves follow a straight line. |
| How to determine accuracy |
1. Compare with ceritified reference 2. Compare results from one or two analytical methods. 3. Analyze blank sample spiked with known analyte. 4. Standard addition
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| How to determine precsion |
Instrument precision(repetitive injections) Intra-assays: Same person, smae method Ruggedness: different people, day, instruments Inter-laboratory: the greatest
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| Range |
| Concentration over which reliable data can be obtained. |
| Detection limit |
| Smallest quantity of analyte that is significantly different. 3s/m |
| What does the slope of a calibration graph tells us? |
| Method sensitivity. |
| Minimum limit of detection Lower limit of quantification |
| 3s/m 10s/m |
| What does the method of standard addition require? |
| Linear response to analyte. |
| Standard addition and internal standard |
Standard: Known quantity of analyte is added Internal: Known quantity of non analyte is added. |
| When are internal standards useful? |
| When quantity of sample analyzed or instrument reponse varies from time to time because of uncontrollable conditions. |
| Signs of S, H, G and K when a reaction is favored. |
S>0 H<0 G<0 K>1 |
| Common Ion effect |
| Salt is less solubl when constituent ions are already in mixture. |
| Through what atom does water bind to cationS?? |
| Oxygen |
| Which ions bind to molecules more tightly? |
| Smaller more highly charged. |
| What is ionic strength? How is ionic strength increased? |
| Total concentration of ions in solution. Inert salt is added. |
| As ka increases |
| pKa decrease; acid strength decreases |
| End point on a titration curve |
Volume where slope is greatest Maximum of first derivative The inflection point of the second derivative |
| What is a current |
The quantity of charge flowing each second through a circuit. 1A = 1C/S |
Relationship between charge and mole. Work and voltage. Free energy and electric potential. Ohms law Electric power |
q=nF Work= Eq deltaG=-nFE I= E/R P= Work/S=EI |
Oxidation electrode Reduction electrode |
Anode Cathode |
| What does a galvanic cell use to generate electricity? |
| Spontaneous reaction. |
| What SHE? and what is it used for? |
| It is the standard hydrogen electrode. Consist of a catalytic Pt surface, and an acidic solution. Used to deduce the standard electric potential of other cells. |
| Refrence electrode. |
| Maintains a fixed potential. |
| Junction potential and causes it? |
| Voltage difference formed when two dissimilar electrolyte solutions are in contact. Greater mobility of one ion compared to the other. The potential will slow down Cl- and accelerate Ag+. |
| What does the difference accross a membrane depend on? |
| Activity of analyte in outer solution. |
| Most common ion-selective electrode |
| Glass electrode |
| Categories of ion-selective electrodes. |
Glass membranes: for H+ and certain monovalent cations Solid-state electrodes: based on inorganic crystals or, recently, conductive polymers Liquid-based electrodes: using a hydrophobic polymer membrane saturated with a hydrophobic liquid ion exchanger Compound electrodes: with an analyte- selective electrode enclosed by a membrane that separates analyte from other species or that generates analyte in a chemical reaction. |
| Advantages and disadvantages of ion-selective electrodes: |
A: Respond linearly to logarithm of analyte over 6 order of magnitude Do not consume unknowns; negligible contamination Fast response time Color and turbity do not hinder them D: Low precision Can be cloaged Fragile and limited shelf life Only measure free analytes |
| Potentiometry vs electrolysis |
1. measures voltage in absence of current. 2. Forces current to make reaction happen. |
| Constant current vs controlled potential coulometry |
| Constant current is linear controlled potential is exponential. |
| What part of the molecule is responsible for light absorption? |
| Chromophore. |
