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Chem 150 > Lab Final MC > Flashcards

Lab Final MC Flashcards

(78 cards)

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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
Precision
refers to the closeness of replicate measurements
26
Alum
potassium aluminum sulfate dodecahydrate KAl(SO4)2 * 12H20
27
Overall formulas of synthesis of alum
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
28
What happens when KOH is added in synthesis of alum?
white bubbles form fizzing turned slight gray
29
What happens when H2O is added in synthesis of alum?
Smoke forms gray bubbling dark gray layer on bottom
30
what happens in second part of synthesis of alum?
white kind of slush initially became more clear
31
Qualitative analysis
the process of figuring out what something is by interrogating the qualities of the substance
32
pH of alum
slightly acidic can use pH test to determine
33
Determining if product has aluminum ions
add aluminon to solution if it turns red, it contains aluminum ions
34
Determining if product has sulfate ions
add barium chloride to solution if precipitate forms, it contains sulfate ions
35
Determining if alum contains water
heat to a constant weight measured mass loss should equal 12 moles of water
36
Density
mass / volume
37
Intensive property
it is independent of the quantity of the substance measured ex: density is intensive
38
Using a volumetric pipette to determine density
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
What indicates precision?
standard deviation
40
How should you round standard deviation
to one significant figure then the number gets put in the same PLACE as the standard deviation
41
3 factors that influence if something is significant
1. absolute difference 2. number of replicate determinations (n) 3. precision of the data
42
What does a 2 sample t test conclude?
if two means are significantly different between two populations
43
Mixture that produces the most energy...
has the least number of moles of reactant left over one closest to the stoichiometric ratio
44
What do data points on the job's plot represent?
amount of energy released
45
Different sides of the job plot
represent different limiting reagents
46
Stoichiometric point
where the two lines meet on the jobs plot no excess
47
how is mole fraction calculated?
calculated by dividing the moles of one component by the total number of moles of all the components
48
reaction to be studied by job's plot
yA + xB = AyB
49
mohr graduated cylinder
like the volumetric pipette can use to measure various volumes make sure going the correct direction when using
50
volume fraction (theta)
volume A / total volume
51
What does the intensity of the color depend on
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
Beer's Lambert Law
A=ecl e= extinction coefficient c= concentration molarity l = path length (centimeters) A = absorbance
53
What color was the solution that we used for the jobs plot?
light red
54
How to determine concentration of NaOH solution?
use titration with KHP
55
Potassium hydrogen phthalate
abbreviated KHP formula = KC8H5O4
56
burette
squeeze bottle used for titrations
57
quantitative transfer
using water/solution to make sure all of a substance is transfered
58
What has to be added to solution for titrations?
phenolphtalein
59
Steps of titration
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
What does the titrant refer to?
NaOH the base
61
Concentration of NaOH in our titration experiment
roughly .1 moles per kg
62
volumetric flask
looks like a bulb with a skinny top
63
Retention of cations
**need to figure out the overview of the experiment** why we did what
64
ammonia
NH3
65
What color did soil solution turn when ammonia was added?
blue
66
Which zeroes are significant in a decimal?
trailing zeroes only ex: 0.03 (no significant zeroes)
67
sig fig rules for addition and subtraction
answer must be the least precise
68
sig fig rules for multiplication and division
answer will be the same as the one with the least number of sig figs
69
idea behind synthesizing calcium chloride
1. add water to metal 2. add HCl to product *hydrogen gas is given off as side product*
70
finding concentration of something that was dilluted
use the absorbance to back solve for concentration with the curve, if you are starting with absorbance use formula V1C1=V2C2
71
relationship between starting aluminum and final alum product
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
amphoteric molecule
can act as an acid or a base
73
example of an amphoteric molecule
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
net ionic equation of test for sulfate ions | barium chloride + sodium sulfate
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
extinction coefficent units
M-1 * cm-1
76
neutralization equivalent
the mass of acid required to react with one mole of hydrogen ion in aqueous solution how much acetic acid is present
77
relationship between neutralization equivalent and molecular weight
NE = molecular weight / (# of acidic hydrogens)
78
neutralization equivalent units
g / mol

Chem 150 (10 decks)

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