CHM 144 final

Question 1

when you are graphing data is the x axis the independent or dependent variable?

Answer 1

the independent variable is plotted on the x axis

Question 2

the variable you are manipulating/ have control over

Answer 2

independent variable

Question 3

the variable you are measuring/ do not have control over

Answer 3

dependent variable

Question 4

does the dependent variable go on the x or y-axis?

Answer 4

y-axis (typically, absorbance, pH, temperature)

Question 5

the most common way to express the precision of a series of measurements

Answer 5

standard deviation

Question 6

how do you calculate standard deviation?

Answer 6

(sum of absolute deviations^2/ n-1)1/2

Question 7

how do you calculate absolute deviations?

Answer 7

l mean of the data points - the sum of all the data points l

Question 8

percent relative standard deviation (RSD%)

Answer 8

(standard deviation/ mean of the data points) *100

Question 9

standard deviation of the mean (s m)

Answer 9

standard deviation/ square root of the number of data points

Question 10

what does increasing n mean in standard deviation of the mean?

Answer 10

increasing precision, the more measurements the more precise

Question 11

what are the steps to performing a Q-test?

Answer 11

1. take all data points and arrange them in increasing order
2. only numbers from the lowest and highest should be considered to be discarded so determine the difference between the outlier and its closest neighbor
3. divide this by the range
4. if the calculated Q is larger than the selected q values it should be discarded

Question 12

what is the purpose of a Q-test?

Answer 12

To determine the validity of an outlier point, only one point can be discarded

Question 13

when is the Q test used?

Answer 13

with data sets between 3 and 10 measurements when one measurement appears to be an outlier

Question 14

formula for density

Answer 14

m/v

Question 15

1 mL =

Answer 15

1cm^3

Question 16

oxidation means what?

Answer 16

oxidation means the loss of electrons

Question 17

reduction means what?

Answer 17

reduction is the gain of electrons

Question 18

if a substance has been oxidized what kind of agent is it?

Answer 18

it is the reducing agent

Question 19

what is the oxidation number for an atom in its elemental form?

Answer 19

zero

Question 20

what can be evidence of a chemical reaction in a solution?

Answer 20

color change, precipitate, deposition of substance onto a metal, gas formation

Question 21

what is the net ionic equation?

Answer 21

an equation that only shows the atoms that directly participate in a reaction, it eliminates the bystander ions

Question 22

how do you know if a reaction was endothermic?

Answer 22

a reaction is endothermic if the reaction feels cold, it is absorbing heat from its surroundings (so the change in enthalpy will be positive)

Question 23

how do you know if a reaction was exothermic?

Answer 23

the reaction produced a warm feeling due to the release of heat

Question 24

ideal gas law

Answer 24

Pv= nRT

Question 25

How do you find the mean of a set of measurements?

Answer 25

x m = sum of all the values/ the number of values

Question 26

how many significant figures does standard deviation have?

Answer 26

two, because it is calculated using absolute deviation

Question 27

t-test for a comparison to an accepted value

Answer 27

l accepted value - mean of data points l> t* standard deviation of the mean

Question 28

what degree of freedom should you use for a t-test comparison to an accepted value?

Answer 28

n-1

Question 29

t-test for two independent measurements of the same quantity (with the same number of data points)

Answer 29

l mean of the data points for 1st set-mean of the data points for 2nd set l > t*(standard deviation of the mean 1st set^2 + standard deviation 2nd set^2)^1/2

Question 30

what degrees of freedom should be used with a t-test with two independent measurements of the same quantity with the same number of data points?

Answer 30

2n-2

Question 31

t-test for two independent measurements of the same quantity without the same number of data points

Answer 31

l mean of data points 1st set - mean of data points 2nd set l > ts12((n 1st set + n 2nd set)/n 1st setn 2nd set)^1/2

Question 32

s 12 =

Answer 32

(((n 1st set -1)(standard deviation 1st set2)+(n 2nd set - 1)(standard deviation 2nd set^2)/(n 1st set + n 2nd set -2)) ^1/2

Question 33

what degrees of freedom should be used with a t-test of two independent measurements with different numbers of data points?

Answer 33

n 1st set + n second set - 2

Question 34

solution of known concentration

Answer 34

titrant

Question 35

solution of unknown concentration

Answer 35

analyte

Question 36

acid-base reaction

Answer 36

AB + CD —- AD +CB

Question 37

why can the three reactions of acidic protons not be distinguished from each other?

Answer 37

Because they are all of similar strength

Question 38

what do acids dissociate into?

Answer 38

H + Anions

Question 39

what do bases dissociate into?

Answer 39

OH- + cation

Question 40

estimate of the equivalence point

Answer 40

end point

Question 41

M (molarity) =

Answer 41

moles/ volume

Question 42

how many significant figures should be used in erlenmeyer flask measurments?

Answer 42

2 sig figs

(EX: 35 mL or 23 mL)

Question 43

how many decimal places is a graduated cylinder reported to?

Answer 43

1 place

eg: .1

Question 44

how many decimal places is a volumetric flask reported to?

Answer 44

2 places

eg: .01

Question 45

how many decimal places are scale measurments recorded to?

Answer 45

3 places

eg: .001

Question 46

charles law

Answer 46

V1/ T1 = V2/T2

Question 47

boyles law

Answer 47

P1 *V1 = P2 *V2

Question 48

avogadros law

Answer 48

P1/N1 = P2/N2

Question 49

Gay-Lussacs law

Answer 49

P1/T1 = P2/T2