midterm exam coverage Flashcards
it is the equilibrium constant for a solid substance dissolving in an aqueous solution
solubility product constant (Ksp)
it is the concentration of solute in a saturated aqueous solution
molar solubility
if an external stress is applied to a system at equilibrium, the system adjusts in such a way that the stress is partially offset as the system reaches a new equilibrium position
le chatelier’s principle
change in equilibrium: increase concentration of products
shift to left
change in equilibrium: decrease concentration of products
shift to right
change in equilibrium: increase concentration of reactants
shifts to right
change in equilibrium: decrease concentration of reactants
shifts to left
change: increase in pressure
side with fewest moles of gas
change: decrease pressure
side with most moles of gas
change: decrease volume
side with fewest moles of gas
change: increase volume
side with most moles of gas
used to judge the quality of experimental measurements
statistical calculations
indicates the closeness of the measurement to its true or accepted value
accuracy
describes the reproducibility of measurements or the closeness of the results
precision
causes data to be scattered more or less symmetrically around a mean value
random error / indeterminate
causes the mean of a set of data to differ from the accepted value
systematic / determinate error
this error occasionally occurs, is often large, and may cause a result to be either high or low.
it also leads to outliers, results that appear different from the data set
gross error
systematic error: caused by imperfections in measuring devices and instabilities in their components
instrument error
systematic error: nonideal chemical or physical behavior of the reagents and reactions upon which analysis is based
method error
systematic error: measurements requiring personal judgment (personal limitations).
personal error
systematic errors can be either?
constant errors
proportional errors
type of systematic error: independent of the size of the sample being analyzed
constant errors
type of systematic error: increased or decreased in proportion to the size of the sample.
proportional errors
what are the 3 ways to detect systematic errors?
- Analysis of reference standards
- Analysis of the blank samples
- Varying the sample size
what is denoted by s
standard deviation
the absolute value of the coefficient of variation
relative standard deviation
the measure of the relative dispersion of data points in a data series around the mean
coefficient of variation
describe the precision of a set of replicate results.
it is the difference between the largest value in the set and the smallest.
spread / range (w)
an expression of the uncertainty of a measurement expressed in plus-or-minus the last digit
absolute uncertainty
ratio of the absolute uncertainty in a measurement to the value of the measurement. It can be expressed in pph, ppt or ppm
relative uncertainty
the variance of a sum or difference is equal to the sum of the individual variances, which demonstrates how the errors propagate
propagation of errors
the weighted average of standard deviations for 2 or more groups
commonly used in t-tests and ANOVA
it can be used to calculate repeatability and within-lab reproducibility
pooled standard deviation
a numerical interval around an experimentally determined mean that contains μ with a certain degree of probability
can be determined by the normal distribution curve
confidence level
what is the numerical magnitude of the confidence limit?
confidence interval
what is the probability of a result outside the confidence interval?
significance level
a measurement that is not consistent with the other set of measurements
outlier
One of the most common significance tests for identifying an outlier
Use if there are no known reasons for an outlier data point
dixon’s Q test
Qexp in Q test stands for?
test statistic
Xi in Q test represents?
measure of a potential outlier
Q Test Hypothesis Testing
there are no outliers present in the data
null hypothesis
Ho
Q Test Hypothesis Testing
there is an outlier present in the data
alternative hypothesis
Ha
Q Test Hypothesis Testing
if Qexp > Qcrit
reject Ho, accept Ha
meaning, may outlier na present talaga
Q Test Hypothesis Testing
if Qexp < Qcrit
fail to reject Ho
meaning, walang outlier
steps to determine if there is an outlier using Q test
- state the null and alternative hypothesis
- identify the test and the test statistic to be used
- state the decision rule based on the rejection region
- compute the Qexp based on the given values
- apply the decision rule and make a decision
- interpret the results based on the decision and make a conclusion
recommended by the International Standards Organization (ISO) and the American Society for Testing and Materials (ASTM)
use to check suspected outliers in a normally distributed data
grubb’s test
Gexp stands for?
the test statistic
Grubb’s Test Hypothesis Testing
if Gexp > Gcrit?
then reject Ho, accept Ha
meaning, may outlier
Grubb’s Test Hypothesis Testing
if Gexp < Gcrit?
then fail to reject Ha
walang outlier
steps to use grubb’s test
- state the null and alternative hypothesis
- identify the test and the test statistic to be used
- state the decision rule based on the rejection region
- compute the mean, standard deviation, Gexp based on the given values
- apply the decision rule and make a decision
- interpret the results based on the decision and make a conclusion
accounts for the variability given by the sample standard
deviation/s
used in determining significant difference in means of smaller samples
T-statistic / T-Test
2 types of t-test
unpaired and paired samples
T-Test Hypothesis Testing
there is no significant difference between the means
for unpaired samples
null hypothesis
Ho
T-Test Hypothesis Testing
2 types of alternative hypothesis
one-tailed
two-tailed
T-Test Hypothesis Testing
u1 ≠ u2; there is a significant difference between the mean
two-tailed
Ha
T-Test Hypothesis Testing
u1 > u2; there is a significant difference between the means, the mean of the 1st data set is greater than the mean of the 2nd data set
one-tailed
T-Test Hypothesis Testing
u1 < u2 in an alternative hypothesis means that…
there is a significant difference between the means, the mean of the 1st data set is less than the mean of the 2nd data se
critical values for tcrit based on ____ degrees of freedom
N - 2
steps in using t-test for unpaired samples
- state the null and alternative hypothesis
- identify the test and the test statistic to be used
- state the decision rule based on the rejection region
- solve for the test statistic, t based on the given values
- apply the decision rule and make a decision
- interpret the results based on the decision and make a conclusion
it is for two samples with data sets that are collected in the same manner and can be matched with one another
t-test paired samples
T-Test Hypothesis Testing (Paired)
ud = △0; there is no significant mean difference between pairs
null hypothesis
Ho
T-Test for Paired Alternative Hypothesis (Ha)
ud ≠ △0
There is a significant mean difference between pairs
two-tailed
T-Test for Paired Ha
ud > △0
one-tailed
The mean significant difference between pairs is greater than zero
T-Test for Paired Ha
ud < △0
one-tailed
The mean significant difference between pairs is less than zero
steps to use t-test
- state the null and alternative hypothesis
- identify the test and the test statistic to be used
- state the decision rule based on the rejection region
- solve for the test statistic and t based on the given values
- apply the decision rule and make a decision
- interpret the results based on the decision and make a conclusion
