chapter 3 Flashcards

1
Q

what is one mole

A

one mole of a substance is the amount of substance which contain as many formula units as there are atoms in 12g of carbon 12. 6.02 x 10^23

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2
Q

units of mol

A

g mol^-1

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3
Q

moles equation

A

moles = mass/molar mass

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4
Q

what is molecular formula?

A

number of atoms of each element in a compound

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5
Q

what is emperical formula

A

simplest whole number ratio of the ratio of atoms of each element in a compound

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6
Q

when is emperical formula used?

A

when substances arent molecules and instead exist as giant crystaline structure

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7
Q

what is relative molecular mass

A

mr - compares mass of a molecule w the mass of a carbon 12 atom

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8
Q

how is relative formula mass different to relative molecular madd?

A

it is the total atomic mass for an emperical formula compound

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9
Q

how to calculate emperical formula from mass?

A

convert mass into moles, divide the moles by the value w the smallet moles

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10
Q

how to calculate molecular formula from percentages?

A

percentage/Mr
divide moles of each value by the smallest mole
then do the relative molecular mass/mr of emperical formula
take the value and times it by the emperical formula e.g. ch2o x 6 = c6h12o6

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11
Q

why are coloured crystals said to be hydrated?

A

water is a part of there structure

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12
Q

anhydrous

A

when water is removed, turns white

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13
Q

why is getting the formula from an experiment not always accurate?

A
  • assumes all water has been lost (if colour change is little its hard to tell when al water is lost, so keep heating till mass no longer changes)
  • assumes there is no further decomposition (salts decompose and change colour when heated, so its hard to judge colour change)
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14
Q

1cm3 in ml

A

1ml

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15
Q

1 dm3 in cm3

A

100cm3

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16
Q

1 dm3 in ml

17
Q

1 dm3 in l

18
Q

concentration equation

19
Q

what is a standard solution?

A

a solution of known concentration

20
Q

how is standard solution produced?

A

dissolving an exact mass of solute in a solvent making the solution to an exact volume

21
Q

how to work out standard solution calc

A

find mol of substance using n = c x v
use m=n x mr to find mass that needs to be dissolved

22
Q

what is molar gas volume?

A

Vm - volume per mole pf gas molecules at a stated temperature and pressure

23
Q

what is STP

A

standard temperature and pressure

24
Q

what is RTP

A

room temperature pressue, 24 dm3 mol^-1
20 c and 101 kpa

25
molar gas volume equation
moles = volume/Vm if dm3 24 if cm3 24000
26
limitations of RTP
conditions are not always room temperature and pressure
27
ideal gas equation
pV = nRT
28
units for ideal gas equation
p - pressure pa V - volume m3 n - mol R - gas constant - 8.34jmol-1k-1 T - tem - kelvin
29
cm3 to m3 dm3 to m3 c to k kpa to pa
x 10^-6 x10^-3 +273 x 10^3
30
what is the ratio of balanced equations called?
stoichemotry
31
percentage yield equation
actual yield/theoretical yield x 100
32
why is theoretical yield less than actual yield?
reaction not gone to completion side reactions may have taken place purification of product may mean loss of some product
33
what is atom economy used for?
measure of how well atoms have been utilised
34
atom economy equation
mr of desired product/mr of all products x 100
35
why is high atom economy important?
produce large proportion of desired product sustainability make best use of natural resources