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Chem 150 > Lab Final MC > Flashcards

Lab Final MC Flashcards

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1
Q

What pieces of information are needed for molecular weight?

A
  1. mass

2. number of moles

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2
Q

How can you determine number of moles of a gas?

A

pressure and volume at a specific temp

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3
Q

Water displacement method

A

can calculate volume of gas

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4
Q

How do you get mass of gas?

A

weigh the lighter before and after dispensing

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5
Q

analytical balance

A

measures to 0.0001 g

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6
Q

Pieces of information to record in fuel of a lighter

A

atmospheric pressure
temperature
mass of the gas
volume of the gas

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7
Q

2 forms of bromothymol blue

A

yellow and blue

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8
Q

Acid base reaction experiment

A

use bromothymol blue

add 0.1M HCl (acid) and 0.1M NaOH

HCl makes blue turn yellow

NaOH makes blue

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9
Q

What color is bromothymol blue at first?

A

green

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10
Q

Sodium alginate

A

polymer that builds cell walls of seaweed and kelp, used as a gel, thickens products

C6 H7 O6 Na

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11
Q

Calcium chloride

A

CaCl2

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12
Q

Synthesize calcium chloride overall formulas

A

calcium metal + water = calcium hydroxide

calcium hydroxide + HCl = calcium chloride

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13
Q

Molarity of HCl used to synthesis calcium chloride

A

3M

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14
Q

What happens when calcium chloride and sodium alginate interact?

A

Jelly like product

strands of sodium alginate are connected by Ca in middle

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15
Q

Molarity (M)

A

moles / volume

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16
Q

What happens when calcium metal is added to water?

A

bubbling fizzing, white grain on bottom

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17
Q

What does calcium solid look like?

A

Gray and flaky

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18
Q

What wavelength to use for urine absorbance?

A

470 nm

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19
Q

What is in urine that we measured?

A

phosphate

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20
Q

Error

A

measured value - true value

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21
Q

Random error

A

results from limitations of measurement device

has an equal chance of being positive or negative

statistical variation

take the average to reduce

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22
Q

Systematic error

A

bias in the system

may be either positive or negative

can be detected and corrected

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23
Q

Finding uncertainty

A

calculate % errors

then add calculated random error to find uncertanity in %

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24
Q

How to calculate random error

A

the uncertainity is half of the smallest division of a scale

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25
Q

Precision

A

refers to the closeness of replicate measurements

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26
Q

Alum

A

potassium aluminum sulfate dodecahydrate

KAl(SO4)2 * 12H20

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27
Q

Overall formulas of synthesis of alum

A

Al(s) + KOH (aq) + H2O = KAl(OH)4 (aq) + H2 (g)
oxidation-reduction reaction

KAl(OH)4(aq) + H2SO4(aq) + H2O = KAl(SO4)2*12H2O(s)
acid-base reaction

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28
Q

What happens when KOH is added in synthesis of alum?

A

white bubbles form

fizzing

turned slight gray

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29
Q

What happens when H2O is added in synthesis of alum?

A

Smoke forms

gray bubbling

dark gray layer on bottom

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30
Q

what happens in second part of synthesis of alum?

A

white kind of slush initially

became more clear

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31
Q

Qualitative analysis

A

the process of figuring out what something is by interrogating the qualities of the substance

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32
Q

pH of alum

A

slightly acidic

can use pH test to determine

33
Q

Determining if product has aluminum ions

A

add aluminon to solution

if it turns red, it contains aluminum ions

34
Q

Determining if product has sulfate ions

A

add barium chloride to solution

if precipitate forms, it contains sulfate ions

35
Q

Determining if alum contains water

A

heat to a constant weight

measured mass loss should equal 12 moles of water

36
Q

Density

A

mass / volume

37
Q

Intensive property

A

it is independent of the quantity of the substance measured

ex: density is intensive

38
Q

Using a volumetric pipette to determine density

A
  1. measure the mass of the empty beaker
  2. use volumetric pipette to dispense the correct amount of liquid
  3. measure the mass of the full beaker, subtract

make sure to record temperature

39
Q

What indicates precision?

A

standard deviation

40
Q

How should you round standard deviation

A

to one significant figure

then the number gets put in the same PLACE as the standard deviation

41
Q

3 factors that influence if something is significant

A
  1. absolute difference
  2. number of replicate determinations (n)
  3. precision of the data
42
Q

What does a 2 sample t test conclude?

A

if two means are significantly different between two populations

43
Q

Mixture that produces the most energy…

A

has the least number of moles of reactant left over

one closest to the stoichiometric ratio

44
Q

What do data points on the job’s plot represent?

A

amount of energy released

45
Q

Different sides of the job plot

A

represent different limiting reagents

46
Q

Stoichiometric point

A

where the two lines meet on the jobs plot

no excess

47
Q

how is mole fraction calculated?

A

calculated by dividing the moles of one component by the total number of moles of all the components

48
Q

reaction to be studied by job’s plot

A

yA + xB = AyB

49
Q

mohr graduated cylinder

A

like the volumetric pipette

can use to measure various volumes

make sure going the correct direction when using

50
Q

volume fraction (theta)

A

volume A / total volume

51
Q

What does the intensity of the color depend on

A
  1. kind of molecule doing the absorbing
  2. the concentration
  3. the path length the light passes through
  4. the solvent the molecule is dissolved in
52
Q

Beer’s Lambert Law

A

A=ecl

e= extinction coefficient

c= concentration molarity

l = path length (centimeters)

A = absorbance

53
Q

What color was the solution that we used for the jobs plot?

A

light red

54
Q

How to determine concentration of NaOH solution?

A

use titration with KHP

55
Q

Potassium hydrogen phthalate

A

abbreviated KHP

formula = KC8H5O4

56
Q

burette

A

squeeze bottle used for titrations

57
Q

quantitative transfer

A

using water/solution to make sure all of a substance is transfered

58
Q

What has to be added to solution for titrations?

A

phenolphtalein

59
Q

Steps of titration

A
  1. weigh acid
  2. quantatively transfer
  3. dillute to 50mL
  4. add phenolphtalein
  5. stir
  6. add base
  7. measure how much base used to achieve pink
60
Q

What does the titrant refer to?

A

NaOH

the base

61
Q

Concentration of NaOH in our titration experiment

A

roughly .1 moles per kg

62
Q

volumetric flask

A

looks like a bulb with a skinny top

63
Q

Retention of cations

A

need to figure out the overview of the experiment

why we did what

64
Q

ammonia

A

NH3

65
Q

What color did soil solution turn when ammonia was added?

A

blue

66
Q

Which zeroes are significant in a decimal?

A

trailing zeroes only

ex: 0.03 (no significant zeroes)

67
Q

sig fig rules for addition and subtraction

A

answer must be the least precise

68
Q

sig fig rules for multiplication and division

A

answer will be the same as the one with the least number of sig figs

69
Q

idea behind synthesizing calcium chloride

A
  1. add water to metal
  2. add HCl to product

hydrogen gas is given off as side product

70
Q

finding concentration of something that was dilluted

A

use the absorbance to back solve for concentration with the curve, if you are starting with absorbance

use formula V1C1=V2C2

71
Q

relationship between starting aluminum and final alum product

A

positive, linear relationship until the graph flattens out at around 1.7g

at this point KOH acts as a limiting reagent and there is not enough to yield more alum

72
Q

amphoteric molecule

A

can act as an acid or a base

73
Q

example of an amphoteric molecule

A

alum

can act as an acid in the presence of OH-

donates a proton to the hydroxide

this is why the precipitate turns clear as more base is added

74
Q

net ionic equation of test for sulfate ions

barium chloride + sodium sulfate

A

Ba2+ + SO4 2- = BaSO4 (solid)

that is why precipitate forms

can disregard chloride and sodium when writing net equation

just use metal and sulfate to show what made the precipitate

75
Q

extinction coefficent units

A

M-1 * cm-1

76
Q

neutralization equivalent

A

the mass of acid required to react with one mole of hydrogen ion in aqueous solution

how much acetic acid is present

77
Q

relationship between neutralization equivalent and molecular weight

A

NE = molecular weight / (# of acidic hydrogens)

78
Q

neutralization equivalent units

A

g / mol

Chem 150 (10 decks)

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