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AA IB Chemistry HL > Structure 1.4-1.5 > Flashcards

Structure 1.4-1.5 Flashcards

(66 cards)

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1
Q

What is the Avogadro constant?

A

number of particles in one mole of substance
6.02 x 10ˆ23

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2
Q

What is a mole?

A

the unit used to measure the amount of substance by the number of elementary entities etc

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3
Q

How many elementary entities are in one mole?

A

the avogadro constant - 6.03*10^23

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4
Q

To which isotope are masses of atoms compared to?

A

on a scale relative to C-12

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5
Q

How to we calculate the relative formula mass Mr for a compound?

A

adding the masses of all the atoms in the formula

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6
Q

What are the units of molar mass M?

A

g/mol

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7
Q

number of moles =

A

mass/Mr

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8
Q

What is the empirical formula of a compound?

A

the formula that gives the simplest ratio of atoms of each element present in the compound

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9
Q

What is the molecular formula?

A

the formula that gives the actual number of atoms of each element in a molecule

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10
Q

Empirical vs molecular

A

empirical: simplest ratio
molecular: actual number

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11
Q

number of moles (in a solution) =

A

concentration(moldmˆ-3) * volume(dmˆ3)

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12
Q

What is the molar mass?

A

the mass of one mole of a substance

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13
Q

How can you calculate percentage compositions? (of an atom in a compound)

A

mass of atoms/total molar mass of the compound * 100

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14
Q

What is concentration?

A

number of particles/moles in a given volume

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15
Q

one litre =

A

one dmˆ3 and 1000 cmˆ3

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16
Q

concentration in g/dmˆ3

A

mass of solute/total vol of solution

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17
Q

concentration in mol/dmˆ3

A

mols of solute/total vol of solution

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18
Q

What determines how many gas particles can fit inside a container?

A
  • volume of container: bigger volume allows for more particles
  • temperature of the gas: faster particles need more space
  • pressure of the gas: more particles means higher pressure
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19
Q

What is the general Avogadro’s law for gases reacting?

A

equal volumes of all gases contain equal numbers of molecules under constant temperature and pressure

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20
Q

Percentage uncertainty:

A

absolute uncertainty/data value *100

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21
Q

volume of a gas =

A

22.7*n

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22
Q

What are concordant titres?

A

those within 0.2cmˆ3 of each other

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23
Q

How can concentration be expressed?

A

in square brackets

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24
Q

Apparatus needed to prepare a primary standard solution:

A

mass balance and volumetric flask

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25
Primary vs secondary standard solutions
Secondary standard solutions are made by diluting a primary standard solution
26
What is the process of preparing a primary standard solution?
1. measure mass of solute (high purity + stored properly to ensure exposure to air/ light/water vapour does not affect it) 2. dissolve solute in a small quantity of solvent in a beaker, mixed with a stirring rod until no solid particles are visible 3. contents of the beaker transferred to a volumetric flask 4. beaker rinsed with solvent and emptied into the volumetric flask 5. volumetric flask filled close to the line with solvent 6. drops of solvent are slowly added until the meniscus is sitting on the line. 7. stopper is added and the entire contents are inverted, thoroughly mixing the solution so there is a uniform distribution of solute
27
Apparatus needed to prepare a secondary standard solution
pipette - volume of primary standard solution volumetric flask
28
What is the process of preparing a standard secondary solution?
1. volume of primary solution is measured with a pipette 2. contents of the pipette transferred to a volumetric flask, and every drop of solution must be emptied into the flask 3. may need to rinse pipette with a small volume of solvent and empty it into the flask 4. volumetric flask filled close to the line with solvent 5. drops of solvent are slowly added until the meniscus is sitting on the line 6. stopper is added and flask is inverted
29
What do spectrophotometry or colorimetry do?
measure how much light is absorbed by the solution
30
What is Beer's law?
absorbance of light and concentration are directly proportional
31
What is absorbance?
a relative comparison of the quantity of light applied and that leaves a sample
32
Units of absorbance
none - it is a relative measure
33
How can you determine an unknown concentration using absorbance?
measuring the absorbance for known concentrations at a specific wavelength and constructing a calibration curve
34
How is a calibration curve constructed?
sample scanned across many wavelengths to see which colour has the greatest absorbance prepared dilutions of the solution are each scanned at that wavelength to measure the absorbance
35
Identify and explain random errors in colorimetry/spectrophotometry.
- anomalies in data points - incorrectly preparing one dilution - dirty/scratched cuvette - calibration error in apparatus
36
Identify and explain systematic errors in colorimetry/spectrophotometry
- when entire calibration curves are higher or lower but have the same gradient - incorrectly calibrated apparatus - way too high concentrations - light caused sample to degrade - incorrect wavelength used
37
What are the main assumptions of the ideal gas model?
- gas particles are constantly moving randomly and in straight lines - negligible intermolecular forces - collisions between particles/with walls are elastic - particles have negligible volume due to distance between them being much greater - average k.e is directly proportional to absolute temp in K
38
What determines pressure?
how frequently the particles hit the walls of the container expressed in Pa or kPa
39
What does the kinetic molecular model suggest?
in an ideal gas, most is empty space, so size of particles and interaction between them are negligible collisions are elastic
40
What are real gases?
gases that deviate a little bit from ideal gas behaviours
41
How does pressure affect the ideal gas model?
low pressure: ideal gas behaviour due to distance between particles and forces between them being negligible high pressure: particles close together are influenced by forces of attraction
42
How does temperature affect the ideal gas model?
low temp: slower particles means there is more opportunity for intermolecular forces to have an effect
43
Under which conditions is a gas considered a real gas?
low temperature high pressure (same conditions in which gases are liquified)
44
Relationship between molar mass and intermolecular forces in gases
the strength of these attractions will increase as molar mass increases
45
How does molar mass affect ideal gas behaviour?
lighter molecules will move faster, experiencing weaker intermolecular forces, showing more ideal behaviour
46
Relationship of temp with volume
Increasing temperature--->greater speed---->more frequent collisions with the walls ---> expanding the volume
47
What is molar volume?
22.7dmˆ3, the volume of 1 mole of any gas under STP
48
What are standard conditions STP?
standard temp and pressure, 273K and 100kPa
49
units of molar volume
dmˆ3/mol
50
amount of gas in moles =
volume/22.7 at STP volume/molar volume
51
Relationship of pressure and volume
inversely proportional
52
A graph of pressure against 1/V...
is a straight line
53
P1V1=
P2V2 at constant temperature
54
kPa corresponds to
dmˆ3
55
dmˆ3 corresponds to
kPa
56
What is the relationship between vol and temp?
volume of an ideal gas is directly proportional to its absolute temperature in K (at constant pressure and w a fixed mass)
57
ratio of volume to temperature
is constant therefore V1/T1 = V2/T2
58
What unit of temp must be used when calculating ratio of vol to temp?
KELVIN used for vol/temp ratios
59
Relationship between pressure and temp
pressure of an ideal gas is directly proportional to its absolute temperature in kelvin (at constant volume and with a fixed mass)
60
P/T=
k
61
the ratio of pressure to temp...
is constant so P1/T1 = P2/T2
62
units of volume, pressure and temp to be used together
kelvin, dmˆ3 and kPa (can be any as long as they match)
63
relationship of P, V and T all in one: combined gas law
P1V1/T1 = P2V2/T2
64
What are the constituents of the ideal gas equation?
PV/T = constant V/n = constant since volume and moles of case are directly proportional
65
What is the ideal gas equation? + units
PV = nRT Pa mˆ3 moles Kelvin
66
ideal gas eq and combined gas law
ideal gas eq: PV = nRT combined gas law: P1V1/T1 = P2V2/T2

AA IB Chemistry HL (12 decks)

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