Chem 14BL week 1-4 Flashcards

1
Q

What is accuracy?

A

the closeness of a result to the true value

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2
Q

What is precision

A

the closeness of a set of results to each other; reproducibility of a result; number of significant figures in a result

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3
Q

What are significant figures?

A

any nonzero digit from 1-9; zeros between nonzero digits; ending zeros after a nonzero number with a decimal point

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4
Q

In addition or subtraction, how many number of decimal places in the answer ?

A

the smallest number of decimal places in the data

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5
Q

In multiplication or division, the number of significant figures in the answer

A

the smallest number of significant figures in the data

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6
Q

When taking the log of a number, how many number of decimal places in the answer?

A

the number of significant figures of the number in the log

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7
Q

When taking the antilog of a number, how many number of significant figures in the answer?

A

the number of decimal places of the exponent in the antilog

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8
Q

Standard deviation formula?

A

the square root of the sum of the difference between each entry and the mean squared all over the number of entries

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9
Q

Average deviation formula?

A

the sum of the absolute value of the difference of each individual number and the mean all over the number of entries

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10
Q

Percent relative average deviation?

A

the average deviation divided by the mean multiplied by 100

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11
Q

Absolute error?

A

expresses the margin of uncertainty associated with the measurement; represented by delta; has units

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12
Q

Relative error?

A

also known as percent error, inherent error, or precision; compares the size of the absolute uncertainty with the size of its associated measurement; represented by absolute error divided by the measured quantity; no units

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13
Q

Addition or subtraction of absolute error?

A

change of C equals change of A plus change of B

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14
Q

Multiplication or division of absolute error?

A

change of C equals parantheses change of A divided by A plus change of B divided by B end parantheses multiplied by C

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15
Q

Addition or subtraction of relative error?

A

change of C over C equals change of A divided by C plus change of B divided by C

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16
Q

Multiplication or division of relative error?

A

change of C over C equals change of A divided by A plus change of B divided by B

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17
Q

percent RAD is less than or equal to percent Inherent Error

A

experiment was performed within the precision warranted by the equipment; no need to repeat the experiment

18
Q

percent RAD is greater than percent Inherent error

A

experiment was not performed within the precision warranted by the equipment; experiment should be repeated

19
Q

spectrophotometric analysis

A

measuring the concentration of solutes in solution by measuring the amount of light that is absorbed by the solution in a cuvette placed in the spectrophotometer

20
Q

Beers Law?

A

A equals epsilon, L, C. epsilon depends on wavelength and identity of chemical species. L is in cm. c is the concentration of the colored substance usually in mol/L.

21
Q

Blank solution

A

a solution that contains all the chemical species except the one you want to measure. Purpose is to eliminate background interference

22
Q

Standard solution

A

a solution with a precisely known concentration. purpose is to create a Beer’s Law calibration plot

23
Q

Beer’s Law limitations

A

solution has a low concetration; absorbance range between 0.1 and 1.0; colored solutions; no reaction between species involved; alpha must be fixed during sample analysis; epsilon must be constant

24
Q

Absorption Spectrum

A

plots absorbance versus wavelength. the optimal wavelength corresponds to the maximum absorbance

25
Q

Why use optimal wavelength to plot Beer’s Law Calibration graph?

A

maximize sensitivity of spectrophotometer; maximize slope of Beer’s Law Calibration Plot; minimize error of spectrophotometer

26
Q

Beer’s Law Calibration Plot

A

plots absorbance versus concentration at a specific wavelength; a minimum of three points are needed for a Beer’s law graph; when Beer’s Law is followed, the absorbance is directly proportional to the concentration

27
Q

the color absorbed is complementary to the color transmitted: true or false

A

true

28
Q

parts per million (ppm)

A

mg of solute / L of solution

29
Q

parts per billion (ppb)

A

micrograms of solute / L of solution

30
Q

weight per volume percent (w/v%)

A

g of solute/ 100 mL of solution

31
Q

molarity (M)

A

mol of solute (n) / L of solution (v)

32
Q

normality (N)

A

equivalents of H+ / L of solution –OR– equivalents of OH- / L of solution

33
Q

What is equilibrium?

A

state in which chemical activities or concentrations of the reactants and products have no net change overt time

33
Q

What is equilibrium?

A

state in which chemical activities or concentrations of the reactants and products have no net change overt time

34
Q

Acid? Base? Conjugate Acid? Conjugate Base?

A

proton donor
proton acceptor
species formed when base accepts a proton
species left when acid donates a proton

34
Q

Acid? Base? Conjugate Acid? Conjugate Base?

A

proton donor
proton acceptor
species formed when base accepts a proton
species left when acid donates a proton

35
Q

strong vs weak acid/base

A

dissociates completely/ partially dissociates in aqueous solution

35
Q

strong vs weak acid/base

A

dissociates completely/ partially dissociates in aqueous solution

36
Q

Equilibrium Constant (K)

A

determines the extent of the reaction (whether it lies to the left or right side of the equation)

36
Q

Equilibrium Constant (K)

A

determines the extent of the reaction (whether it lies to the left or right side of the equation)

37
Q

relationship between K, pK, and acid/base

A

the smaller the value of the K(a), the greater the value of pK(a) and the weaker the acid
the smaller the value of K(b), the greater the value of pK(b) and the weaker the base

37
Q

relationship between K, pK, and acid/base

A

the smaller the value of the K(a), the greater the value of pK(a) and the weaker the acid
the smaller the value of K(b), the greater the value of pK(b) and the weaker the base