EXPERIMENT 1 Statistical Analysis Flashcards
Analytical Chemistry Lab Exam
Amount of matter in an object
Mass
Weighing by Difference:
Mass Object Formula
Mass Object Formula =
mass container + object to weigh - mass empty container
Making use of “Tare” button or re-zero
Direct Weighing
Direct Weighing:
Making use of “_____” button or _______.
“Tare”
Re-zero
It is the accuracy of ± 1mg and are suitable for most weighing of amounts that are specified to only two or three significant figures.
Top-Loading Balance
Accuracy of ± 0.1 mg and must be used whenever you desire four or more significat figure.
Analytical Balance
Always check that the _______ is level before using it.
Balance
Do not handle objects to be ____ with bare hands. _______, ______ and _____ on your fingers will affect the weight of the objects.
Weighed
Moisture, Grease and Dirt
To be weighed accurately, all objects must be at ______________.
Room Temperature
Never weigh chemicals directly in contact with the _________. Use containers such as ______, _____ and _____.
Balance pan.
Beakers, Flasks, Weighing Bottles
Do not spill ____. Always keep the _______ clean
Chemicals
Balance
The goal of Calibration of Pipet:
To minimize any measurement __________ by ensuring the_______ of test equipment.
uncertainty
accuracy
Space occupied by matter
Volume
Liquid: Correct choice of ______/ ____
Glassware/instrument
______ and ____ were not designed to measure volumes accurately.
Beakers/Flasks
Pipet used in the experiment
Serological Pipet
It is the process of configuring an instrument to provide a result for a sample within an acceptable range.
Calibration
Scale Increment
To find the scale increment:
1. _________ the values of any two adjacent labeled _________
Subtract
Graduation
Scale Increments
To find the scale increment
2. _________ by the number of ____ between them.
Divide
Intervals
This technique works for thermometers, Spring scales, and other measuring instruments as well.
Scale Increments
It is complete set.
Population
- Subset of population
- Represent the bulk material you want to analyze
- Obtained through the process of sampling
Sample
Also referred to as measures of center or central location.
Measure of Central Tendency
It is a summary measure that attempts to describe a whole set of data with a single value that represents the middle or center of its distribution.
Measure of Central Tendency
It is the sum of the value of each observation in a dataset divided by the number of observations.
Mean
it is the middle result in distribution when the values are arranged in ascending or descending order. (Both sample and population)
Median
Describes the reproducibility of measurements; the closeness of results to each other.
Precision
- Also called spread
- Another term to describe the precision of a set of replicate results.
Range R
- Comparison of each of the individual values to arithmetic means.
- Measure of how closely the individual results or measurements agree with each other.
Sample StandardDeviation (s)
Far from the mean
Large std. dev
Close to the mean
Small Standard deviation
Scale Increment
To find the scale increment:
2. _____ by the number of _______ between them
Divide
Intervals
This technique works for thermometers, spring scales, and other measuring instruments as well.
Scale Increments
It is complete set
Population
- subset of population
- represents the bulk material you want to analyze
- obtained through the process of sampling
Sample
also referred to as measures of center or central location
Measure of central tendency
is a summary measure that attempts to describe a whole set of data with a single value that represents the middle or center of its distribution
Measure of central tendency
- sum of the value of each observation in a dataset divided by the number of observations.
Mean
is also known as the arithmetic average
Mean
it is the middle value in distribution when the values are arranged in ascending or descending order (both sample and population)
Median
describes the reproducibility of measurements; the closeness of results to each other.
Precision
- Also called spread
- Another term to describe the precision of a set of replicate results.
Range R
- comparison of each of the individual values to the arithmetic mean
- measure of how closely the individual results or measurements agree witheach other
Sample Standard deviation (s)
a statistically useful description of the scatter of the values determined in a series of runs
Sample Standard. deviation (s)
far from the mean
Large Standard deviation
close to the mean
small std. dev
- ratio of the standard deviation to the mean
- another method of describing precision
Coefficient of Variation CV
high variation; greater level of dispersion around the mean
CV > 1
low variation; smaller level of dispersion around the mean
CV < 1
indicates the closeness of the measurement to its true or accepted value and is expressed by the error.
Accuracy
two values resulting from calculating the confidence interval.
Confidence Limit =
sample mean ± margin of error
provide our best estimate of the population’s or sample’s mean
Confidence interval
REPORTING COMPUTED DATA:
One of the best ways of indicating reliability is to give a confidence interval at the ____ or ____ confidence level.
90% or 95%
Lowest and Highest Data Point
(if reject or accepted)
Q-Test – test for outliers
- can alter the results of the data analysis.
- can influence the measure of central tendency especially the mean.
Outliers
𝑞𝑢𝑒𝑠𝑡𝑖𝑜𝑛𝑎𝑏𝑙𝑒 𝑑𝑎𝑡𝑎 𝑓𝑜𝑟 𝑡𝑒𝑠𝑡𝑖𝑛𝑔
𝑋𝑞
𝑛𝑒𝑎𝑟𝑒𝑠𝑡 𝑑𝑎𝑡𝑎 𝑝𝑜𝑖𝑛𝑡 𝑡𝑜 𝑋𝑞
𝑋𝑛
Accepted or Not?
If Q < Qcrit
Accepted
Accepted or Reject?
If Q > Qcrit
Reject
