# CHEM 2080 Lecture Notes - Lecture 99: Conjugate Acid, Potassium Chloride, Galvanic Cell

140 views9 pages

:

-If any of the analyte wasn't transferred from a flask after separating it from other

components, there will be an error in the calculations.

-Calibration clock is a graph where you put peak height (y axis) vs analyte

concentration (in parts per million).

- - Certified Reference Material, shows if the results are accurate or not. Not

everything has a CRM, so you cant always check if the results are accurate.

-If there is no CRM, try using other methods and look if you get to the same (or

close) answer.

-Read 3.1 - 3.2 for more info about uncertainty. (review from high school).

- is how accurate the results are

- is how close the results are (they can be far from the real answer but

precise

-If we have to pick one, Accuracy is preferable.

-How to calculate central estimates: for the numbers 1,2,3,4,5,6,7,8,9.

-: (average) add all and divide by 9 = 5.

-: (the middle number) = 5, if even number of results add two mid

numbers and divide by 2.

-You can add variances (the square of standard deviation (SD)) but cannot add SD.

-: subtract the average from each number. Square each

subtraction and add all the squares. Divide by the number of numbers - 1. Square root.

- !: 100 x SD/mean = in %

-Types of errors: "(systematic)and #(random)

-" errors - You can see where you made the error and why. Can be

corrected

find more resources at oneclass.com

find more resources at oneclass.com

-Types of Determinate errors: #nstrumental Error, Method Error, Personal Error,

Constant Error and Proportional Error.

-# error for example if you use a dirty burette.

- error example is if you use a wrong indicator for a substance.

- error for example is when you don't line your eyes on the meter.

- error is when the difference between measured value and true value is

the same, its also called an absolute error. Use large amounts of analyte to minimize

error.

-$ error increases as the amount of analyte increases. Usually happens

when the analyte has contamination.

-We can fix Constant Errors by a %& experiment. A blank measurement is the

analysis of everything the same except its without the analyte. (Its like a control

experiment).

-# errors cannot be corrected. Effect - scattered values around the

mean.

-The statistics samples and population. Mean Standard

dev

-Finite number of measurements is called a $ x(with_on top) s

-Infinite number of measurements is called a $$ µ (true σ (true

-Properties of Gaussian distribution Mean) std v)

-Mean is in the central

-Symmetric (bell-shaped) gaussian equation

-50% below the mean, 50% above the mean

-4768 bulbs.

-Range sqrt(30) - 1100

-Random error

-2 variable

-µ and σ

-Slide 28 correction, against “N” is suppose to be against “z”.

find more resources at oneclass.com

find more resources at oneclass.com

-' = σ^2

-Similarity s^2 = variance

-When we combine two distributions, the variances are additive ( not standard

deviations)

-For different random error processes (1,2,3...n) that contribute to a measurement

error, the total variance.

-σ = sqrt(σ1^2 + σ2^2 + σ3^2 + ... σn^2)

-Coefficient of variation = σ/µ ≈ (s/x)*100%

-Pooled standard deviation is doing standard deviation with sets (see slide 35).

-Sample mean(x) can be measured, but the true mean (population, µ) cannot be

measured, but we can calculate it using the sample mean.

-Degree of freedom is n-1.

-Applications of confidence level: Comparison with a true value and Comparison

with two experimental mean.

-Example on slide 40 is a systematic error.

-T test is for accuracy. Tcalc > Tcritical = yes, there is a significant difference.

-Is there a significant difference (at 95% level) between precisions of the two labs?

Do F test.

-Is there a value that should be rejected from the results (off away from 95%

interval).

-Q test: Q value = gap/range for numbers (,1,2,2,3,3,) gap = 6-3 = 6-

1

-Pg. 67 examples. For errors (not on test).

-Everything in the sample except the analyte is a *. This refers to blank

method.

-$+ is the ability to distinguish the analyte from other compounds in the

sample.

-The range where a method can be reliably used is called a .

-Linear range is not the same as dynamic range.

find more resources at oneclass.com

find more resources at oneclass.com