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Chemistry A Level AQA > 3.1.2- Amounts of substance (PAPER 1 +2) > Flashcards

3.1.2- Amounts of substance (PAPER 1 +2) Flashcards

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1
Q

What is symbol for nitric acid?

A

HNO3

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2
Q

What is symbol for phosphoric acid?

A

H3PO4

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3
Q

What is symbol for nitrate and nitrite ion and sulfate and sulfite ion ion?

A

Nitrate= NO3 - Nitrite= NO2 -

Sulfate= SO4 2- Sulfite= SO3 2-

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4
Q

What is symbol for silicate and chlorate ion?

A

Silicate = SiO3 2-

Chlorate = ClO3 -

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5
Q

What is symbol for carbonate and hydrogencarbonate ion?

A

Carbonate = CO3 2-

Hydrogencarbonate = HCO3 -

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6
Q

What is symbol for hydroxide, hydrogen and hydride ion?

A

Hydroxide = OH-
Hydrogen = H+
Hydride = H-

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7
Q

What is symbol for phosphate ion and ammonium ion?

A

Phosphate = PO4 3-

Ammonium = NH4 +

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8
Q

Symbol for sulfuric acid?

A

Sulfuric acid = H2SO4

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9
Q

Symbol for hydrogen peroxide and ammonia?

A

Hydrogen peroxide = H202

Ammonia = NH3

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10
Q

What are the 7 diatomic molecules?

A

H2, N2, F2, I2 (iodine), Cl2, Br2, O2

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11
Q

What does substance + oxygen make?

A

Oxides

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12
Q

What does metal + water make?

A

Metal hydroxide + hydrogen

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13
Q

What does metal + acid make?

A

Salt + hydrogen

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14
Q

What does oxide OR hydroxide + acid make?

A

Salt + water

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15
Q

What does carbonate OR hydrogencarbonate + acid make?

A

Salt + water + carbon dioxide

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16
Q

What does ammonia + acid make?

A

Ammonium salt

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17
Q

What does metal carbonate make?

A

Metal oxide + carbon dioxide (on heating.)

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18
Q

Write the ionic equation between an acid and a hydroxide.

A

H+ (aq) + OH- (aq) —> H2O (l)

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19
Q

Write the ionic equation between an acid and a carbonate.

A

2H+ (aq) + CO3 2- (aq) —> H2O (l) + CO2 (g)

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20
Q

Write the ionic equation between an acid and a hydrogencarbonate.

A

H+ (aq) + HCO3 - (aq) —> H20 (l) + CO2 (g)

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21
Q

Write the ionic equation between an acid and ammonia.

A

H+ (aq) + NH3 (aq) —> NH4+ (aq)

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22
Q

What are the steps of writing an ionic equation?

A

1) Leave any solids, liquids and gases exactly as they are- put into new equation.

2) Split the ionic aqueous substances into their ions.

3) Eliminate any spectator ions

4) Write the equation including the ions that change.

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23
Q

Write H2SO4 + 2KOH —> K2SO4 + 2H20 as simplest ionic equation.

A

1) Separate into ions

2H+ + SO4 2- + 2K+ + 2OH- —> 2K+ + SO4 2- + 2H20

2) Write without spectator ions

2H+ + 2OH- —> 2H2O

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24
Q

What is definition of relative atomic mass- Ar?

A

Average mass of an atom of an element relative to 1/12th the mass of a Carbon 12 atom.

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25
Q

What is definition of relative molecular mass?

A

Average mass of a molecule of a substance relative to 1/12th of the mass of a Carbon 12 atom.

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26
Q

What is definition of relative formula mass? (ionic compounds)

A

Sum of the relative atomic masses of all the atoms in the formula of a substance.

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27
Q

1 tonne in g?

A

1,000,000g

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28
Q

Why was carbon-12 chosen as the standard?

A

1) It is a stable isotope- it does not undergo radioactive decay so it is reliable.

2) It is abundant and cheap

3) It is a solid at RT, so easy to handle.

29
Q

1 mg in g?

A

0.001g

30
Q

What is avogadro’s constant?

A

The number of particles in 1 mole.

6.022x10^23

31
Q

How many g is 1 mole of oxygen if its Ar is 16?

Why?

A

1 mole of oxygen atoms = 16g

This is because the relative atomic mass of any element in grams contains 1 mole of atoms.

32
Q

How do you work out mass of 1 single atom using avogadro’s constant?

A

Mass of 1 single atom= Ar / 6.022x10^23

33
Q

How do you work out the number of particles using avogadro’s constant?

A

Number of particles= 6.022x10^23 x number of moles

34
Q

What is the moles equation?

A

moles = mass/mr

35
Q

Definition of concentration?

A

A measure of how many particles of solute are dissolved in a given volume of solvent.

Can increase the conc. by dissolving more solute in the given volume of solution or decreasing the amount of solvent.

36
Q

How do you convert from mol/dm3 to g/dm3?

A

x by the Ar

37
Q

How do you convert from g/dm3 to mol/dm3?

A

divide by the Ar.

38
Q

How do you convert from cm3 to dm3?

A

Divide by 1000

39
Q

How do you work out the number of moles in a solution?

A

Number of moles= conc (moldm-3) x volume(dm3)

VOLUME MUST BE IN DM3

40
Q

How do you work out the conc. in gdm-3 if you know the conc. in moldm-3?

A

Conc. = conc. (in moldm-3) x Mr

41
Q

What is the ideal gas equation in word form?

Include all units.

A

Pressure (Pa) x Volume (m3) = Number of moles x Gas Constant (8.31 Jmole-1K-1) x Temperature (K)

42
Q

How do you convert from dm3 and cm3 to m3?

A

dm3 x 10-3 = m3

cm3 x 10-6 = m3

43
Q

How do you convert from kPa and mPa to Pa?

A

kPa x 10^3 = Pa

mPa x 10^6 = Pa

44
Q

How do you convert from degrees C to K?

A

Degrees C + 273

45
Q

Rearrange ideal gas equation for number of moles?

A

n= PV/RT

46
Q

Rearrange ideal gas equation for volume?

A

V= nRT/P

47
Q

Rearrange ideal gas equation for temperature?

A

T= PV/nR

48
Q

Rearrange ideal gas equation for pressure?

A

P= nRT/V

49
Q

Eg % yield question.

How much CaO can be made when 34g Ca is burnt completely in oxygen?

A

1) Write balanced equation
2Ca (s) + O2 (g) —> 2CaO (s)

2)Work out mr of both species involved

mr Ca = 2x40=80
mr 2CaO= 112

3) Divide both these g by 80 then x by 34 to work out the g of Cao.

=47.6g

50
Q

Eg volume of gas question.

What vol H2 is produced when 12g K reacts with H20 at 100kPa pressure, 298K?

A

1) Write balanced equation
2K(s) + 2H20 (l) —> 2KOH (aq) + H2 (g)

2) Work out moles of K
=12/39 = 0.31 mol

3) Use ratio to work out moles of H2
0.31/2= 0.155mol H2

4) Use equation: V=nRT/P
=3.84x10^-3m3

51
Q

Eg titration conc. of acid or alkali question.

18.3cm3 of 0.25moldm-3 HCl required to neutralise 25cm3 KOH. Conc. of KOH?

A

1) Write balanced equation
HCl + KOH —> KCl + H2O

2) Work out moles of HCl
moles= conc. x volume
volume in dm3 so 18.3/1000 = 0.0183
moles= 0.0183 x 0.25= 4.58 x10^-3

3) Work out moles of KOH
moles also = 4.58 x10^-3

4) Work out concentration
conc= mol/vol
volume in dm3 so 25/1000= 0.025
conc=4.58x10^-3 / 0.025= 0.18 mol/dm3

52
Q

Eg titration volume of acid or alkali question.

15.7cm3 of 0.450moldm-3 H2SO4 required to neutralise 0.120moldm-3 of NaOH. Volume of NaOH being neutralised in cm3?

A

1) Write balanced equation
H2SO4 + 2NaOH —> Na2SO4 + 2H20

2) Work out moles of H2SO4
moles= conc (mol/dm3) x volume (dm3)
15.7/1000= 0.0157 dm3
moles = 0.0157 x 0.450 = 7.07x10^-3 mol

3) Work out moles NaOH
1:2 ratio, moles = 2 x 7.07x10^-3= 0.0141mol

4) Work out volume= moles/conc
volume= 0.0141/ 0.120= 0.118dm3

0.118dm3= 118cm3

53
Q

What is the empirical formula?

A

The simplest whole number ratio of elements in a compound.

54
Q

What is the molecular formula?

A

The actual number of atoms of each element in a compound.

55
Q

How do you work out the empirical formula?

A

If there are %’s, write them as g

Convert these masses into moles: moles=mass/mr

Divide all mole values by the smallest mole value

Sub into name of compound

56
Q

How do you work out the molecular formula using the empirical formula?

A

mr of molecular formula/ mr of empirical formula.

x all of the atoms in the empirical formula by the answer from above!

57
Q

What is a definition of theoretical yield?

A

The amount of product produced assuming no products are lost and all reactants react fully.

58
Q

Formula for % yield?

A

mass of product obtained
————————————————- x100
max theoretical mass of product

59
Q

Eg % yield question

32.6g CaO produced, theoretical mass= 47.6g

A

% yield= 32.6/47.6 x 100

=68.5%

60
Q

What is the % atom economy?

A

How efficient a reaction is

mass of desired product as shown in equation
——————————————————- x100
total mass of products as shown in equation

61
Q

Eg % atom economy question.

FE203 can be reduced using C to make pure Fe and CO2. Atom economy in extraction of Fe?

A

FE2O3 + 0.5C—> 2Fe + 0.5CO2

Atomic mass of desired product?
=2 x 55.8(Fe)= 111.6g

sum of molecular masses FE2O3 = (2 x 55.8) + (3x16) + (1.5 x 12) = 177.6

% atom economy = 111.6/177.6 x100= 62.8%

62
Q

What is the formula of a silver ion and a zinc ion?

A

Silver= Ag+
Zinc= Zn 2+

63
Q

When do you use -ate -ite or -ide?

A

-ate if it contains 3 oxygens

-ite if it contains 1 LESS OXYGEN eg
nitrate= NO3 - nitrite= NO2 -

-ide if it only contains 2 elements and NO OXYGENS. ide is attached to negative ion

64
Q

What are the exceptions to -ates having 3 oxygens?

A

sulfate and phosphate both have 4 oxygens

so, sulfite and phosphite will both have 3 oxygens

65
Q

What does the roman numeral next to an element indicate? example of Fe(II)

A

The positive charge/ the number of electrons in the outer shell

Fe(II) has a 2+ charge as it has 2 electrons in its outer shell

66
Q

How to calculate % by mass?

A

(mass of chemical you want ÷ total mass of compound) x 100

67
Q

Why is percentage atom economy useful?

A

-Shows how efficiently raw materials are turned into target product
-High % atom economy= less waste and fewer by products- by products can be sold but some are too invaluable to be sold
-Minimises environmental impact and saves raw materials

68
Q

Describe the overall method of a titration.

A

Known volume of a solution of typically unknown concentration is added to a conical flask using a pipette- usually 25cm3

Clamp burette above conical flask with the other chemical(eg the acid) - this is the standard solution

Indicator is added to conical flask which changes colour once correct volume of acid has been added to burette- place white tile under flask.

Note starting volume of burette, add the solution to the conical flask swirling the flask, stop titration when indicator changes colour.

Record final burette volume which would have gone down. Work out difference between starting burette volume and end burette volume.

69
Q

What are the 2 indicators for titrations and their colours in acid and alkali?

A

1- methyl orange: red in acid, yellow in alkali, end point is orange

2- phenolphthalein: colourless in acid, pink in alkali, end point is just pink when adding alkali or just colourless when adding acid.

Chemistry A Level AQA (25 decks)

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