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Alevel Chemistry OCR A > Module 2: Amount Of Substance Atoms Ions And Compounds > Flashcards

Module 2: Amount Of Substance Atoms Ions And Compounds Flashcards

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1
Q

What is the structure of an atom

A

Protons and neutrons in nucleus and electrons in shells

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2
Q

What is the charge of a proton

A

+1

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3
Q

What is the charge of an neutron

A

0

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4
Q

What the charge of an electron

A

-1

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5
Q

What is the mass of a proton

A

1

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6
Q

What is the mass of a neutron

A

1

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7
Q

What is the mass of an electron

A

1/1836

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8
Q

What is the overall charge of an atom and why

A

Neutral because the total positive charge from protons is equal to the negative charge from electrons

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9
Q

Definition for a mole

A

Amount of substance containing as many particles as there are carbon atoms in exactly 12g of the C-12 isotope

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10
Q

definition for relative atomic mass

A

Weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom if C-12

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11
Q

Definition for relative isotopic mass

A

Weighted mean mass of an atom of an isotope when compare to 1/12th mass of an atom of C-12

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12
Q

What molar mass

A

Mass mole of a substance (g mol-1)

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13
Q

Definition for relative molecular mass

A

Weighted mean mass of a molecule compared to 1/12 of the mass of an atom of C-12

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14
Q

What’s avogadros constant

A

Number of atom per mole of the C-12 isotope (6.02 x 10^23 )

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15
Q

How do you do a reacting mass calculation when given 1 mass

A

Whilst using balanced equation and correct units
1. Mole of known (mol = mass/mr)
2. Mole of unknown (mole ratio)
3. Mass of unknown (mass = mol x mr

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16
Q

What is the solid equation for moles

A

Mole= mass (g) / Mr

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17
Q

What is a limiting reagent

A

Substance in reaction which runs out first

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18
Q

How do you do a limiting reagent mass calculation when given 2 masses

A

Using balanced equation and correct units
1. Mol of both reagents (mol = mass/mr)
2. Find limiting reagent
3. Mol of unknown (mol ratio)
4. Mass of unknown (mass =mol x mr )

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19
Q

What’s an empirical formula

A

Simplest whole number ratio of atoms present in a compound

20
Q

What molecular formula

A

Number of atoms of each element in a molecule

21
Q

How to calculate empirical formula

A
  1. Table with each element
  2. Write % or mass (g)
  3. Find moles of each elements (mol=mass/mr)
  4. Find whole number ratio (divide by smallest)
  5. Formula
22
Q

What does anhydrous mean

A

Substance that contains no water molecules

23
Q

What dies hydrated mean

A

Crystalline and containing water molecules

24
Q

What is water of crystallisation

A

Water molecules that form essential part of the crystalline structure of a compound

25
Q

How do you calculate formula for a hydrated salt

A
  1. Moles of anhydrous (mol=mass/mr)
    2 moles of water (mol=mass/mr)
  2. Ratio to find formula (empirical method)
26
Q

What is the practical for water of crystallisation

A

-mass of crucible
-mass of crucible and hydrated salt
-heat until constant mass (reweigh x2)
-record mass
-mass of anhydrous
-find formula

27
Q

Equation for moles in solution

A

Moles=conc (mol dm-3) x vol (dm^3)

28
Q

Equation for moles in gas

A

Moles = vol(dm^3) / 24

29
Q

What has to be for mol = vol/24 to be true

A

Room temp of 298K and room pressure (101kPa)

30
Q

What’s the ideal gas equation

A

pV = nRT

31
Q

What’s p in pV = nRT

A

Pressure in Pa

32
Q

What’s V in pV = nRT

A

Volume in m^3

33
Q

What’s n in pV = nRT

A

Number of moles

34
Q

What’s R in pV = nRT

A

Ideal gas constant of 8.314 J mol-1 K-1

35
Q

What’s T in pV=nRT

A

Temperature in K

36
Q

How do you convert °C to K

A

+ 298

37
Q

Percentage yield equation

A

% yield = actual yield (mol of product)
—————————————- ——-x 100
Theoretical yield (mol of products

38
Q

What can result in lowered percentage yield

A

-incomplete reaction
-side reaction
-impure substance
-loss through transference

39
Q

What is atom economy

A

Measure of what proportion of a reaction are the desired product and how much is waster

40
Q

Atom economy equation

A

Mass of desired product
—————————————x 100
Total mass of product

41
Q

What is true for atom economy if only 1 product

A

100% atom economy and is ideal

42
Q

What can be used to analyse different elements

A

Mass spectrometry

43
Q

What can mass spectra show

A

Relative isotopic masses and abundances

44
Q

What is on the axis for mass spectrum

A

X axis- mass/charge
Y axis -%isotope abundance

45
Q

What is the equation for relative atomic mass

A

(% x isotopic mass) + ( % x isotopic mass)
———————————————————
100

Alevel Chemistry OCR A (13 decks)

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