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chemistry > amount of substance > Flashcards

amount of substance Flashcards

1
Q

state 7 common diatomic molecules

A

H2
N2
O2
F2
Cl2
Br2
I2

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2
Q

what is a diatomic molecule?

A

elements that exist as two atoms covalently bonded together

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3
Q

what is a molecular ion

A

ions made up of more than one atom

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4
Q

state the charge of:
1) sulphate
2) nitrate
3) carbonate
4) hydroxide
5) ammonium

A

1) 2-
2) 1-
3) 2-
4) 1-
5) 1+

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5
Q

what is an empirical formula

A

simplest whole number ratio of elements in a compound

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6
Q

what is empirical formula used for?

A

ionic and giant covalent compounds

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7
Q

what is the molecular formula?

A

the actual number of atoms of each element in a compound

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8
Q

what is the molecular formula used for?

A

simple covalent molecules

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9
Q

what do ionic ewuations leave out?

A

soectator ions

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10
Q

what are spectator ions?

A

ions that do not take part in a reaction

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11
Q

are ions soectatong if they change state?

A

no

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12
Q

what is avacadros constant?

A

the number of atoms in 12g if carbon-12

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13
Q

give the value of avacadros constant

A

6.022 x 10^23

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14
Q

what is amount measured in?

A

moles

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15
Q

what is the symbol for moles?

A

mol

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16
Q

at Alevel how many decimals are used for RAM?

A

1

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17
Q

what are the units of relative formula mass RFM

A

g mol^-1

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18
Q

what is the equation to calculate moles?

A

mass/Mr

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19
Q

how is the number if particles calculated?

A

mol x L(avacadro constant)

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20
Q

what does L stand for?

A

the avacadros constant

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21
Q

wht is meant by theoretical yield?

A

mass of product you expect to produce

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22
Q

what is meant by actual yield?

A

mass of product produced

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23
Q

how do you calculate % yield?

A

(actual/theoretical) x100

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24
Q

why might you not get 100% yield?

A

incomplete reaction, mechanical transfer, during seperation

25
Q

how do you calculate concentration?

A

mol/volume (dm3)

26
Q

how do you convert cm3 to dm3?

A

dicide by 1000

27
Q

gow do you convert from mL to cm3?

A

1ml = 1cm3

28
Q

how do you calculate the unknown concentration of a solution?

29
Q

what is a bulb pipette used for?

A

accurately measure an exact volume

30
Q

what us a volumetric flask used for?

A

accurately produce an exact concentration

31
Q

where shoukd you read the burette from?

A

bottom of the meniscus

32
Q

what titres are used to calculate an average?

A

thise within 0.1cm3

33
Q

what is a standard solution

A

solution with a known concentration

34
Q

why is the funnel removed in a titration?

A

to stop drops falling into the burette

35
Q

what is the end point in a titration?

A

when the indicator changes colour

36
Q

to what degree of accuracy should the average titre be given?

37
Q

what does M stand for?

38
Q

what is the error in reading the burette?

A

+/-0.5 cm3

39
Q

name two indicators

A

phenolphtalein
methyl orange

40
Q

what colour is ohenolphtalein in acid/base?

A

colourless/pink

41
Q

what colour is methyl orange in acid/base?

A

red/yellow

42
Q

which indicator is used for weak acid-strong base titrations?

A

phenolphtalein

43
Q

which indicator is used for weak acid-strong acid titrations?

A

methyl orange

44
Q

which indicator is used first strong acid-strokg base titrations

A

either methyl orange ir phenolphthalein

45
Q

what volume is occupied by 1 mol of any gas at room temp/pressure

46
Q

state the ideal gas equation

47
Q

what is the unit if pressure

48
Q

what is temoerature measured in

49
Q

how do you convert from oC to K

50
Q

what is room temperature

51
Q

what is R

A

the ideal gas constant

52
Q

what is the value of R

A

8.314 J K-1 mol-1

53
Q

what is volume measured in

54
Q

what do you need to convert an empirical formula to a molecular formula

55
Q

how can the degree of hydration be determined?

A

heating to a constant mass

56
Q

what is atom economy?

A

how efficiently atoms are used in a reaction

57
Q

what is the equation to calculate arom economy?

A

(Mr of desired product/total Mr of all products) x100

58
Q

why do chemists want a high % yield?

A

lots if product produced

59
Q

why do chemists want a high atom economy?

A

less waste

chemistry (6 decks)

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