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x A-level Chem > Module 2 : Section 1 > Flashcards

Module 2 : Section 1 Flashcards

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1
Q

Describe the structure of the atom

A

Orbitals: Hold electrons in place
Nucleus: Where you find protons and neutrons.
Contains most of the mass.

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2
Q

Give the relative mass and relative charge of protons, neutrons and electrons.

A 
Protons:
Mass = 1
Charge = +1
Neutrons:
Mass = 1
Charge = 0
Electrons:
Mass = 1/2000
Charge = -1
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3
Q

What are isotopes?

A

Atoms of the same element with different numbers of neutrons.

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4
Q

Define relative atomic mass.

A

Mean mass of an atom of an element, relative to 1/12th the mass of Carbon-12.

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5
Q

Define isotopic mass.

A

Mass of an atom of an isotope of an element, relative tp 1/12th the mass of Carbon-12.

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6
Q

How do you calculate the isotopic abundance of:
B-10 = 20%
B-11 = 80%

A 
      100
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7
Q

On a mass spectrum, what does the y axis and x axis show?

A

Y axis = Abundance of ions. Height of each peak gives you the relative isotopic abundance.
X axis = mass/charge. Can assume it is the relative isotopic mass.

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8
Q

How would you calculate the relative atomic mass using data from a mass spectrum?

A

Multiply each relative isotopic mass by its relative isotopic abundance and add up the results. (X-axis value multiplied by its height)
Divide by the sum of the isotopic abundances (sum of the heights of the peaks)

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9
Q

Give the equation linking mols, molar mass and mass.

A

mols = mass / molar mass

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10
Q

Give the equation linking mols, volume and molar gas volume (24dm^3)

A 
mols = volume/24 (dm^3)
mols = volume/24000 (cm^3)
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11
Q

What is the ideal gas equation and what does it allow you to calculate?

A 
pV = nRT 
allows you to calculate no of mols at any temperature or pressure.
p = pressure (Pa)
V = volume (m^3) 
1cm^3 = 1x10^-6 m^3
1dm^3 = 1x10^-3 m^3
n = no. of mols
R = 8.314
T = temperature (k) --> K= Degrees celsius + 273
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12
Q

What is the empirical formula?

A

Smallest ratio of atoms of each element in a compound.

ALWAYS MEASURED IN MOLS

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13
Q

What is molecular formula?

A

Actual no. of atoms of each element in a molecule.

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14
Q

How are ions formed?

A

Ions are formed when electrons are transferred from one atom to another.

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15
Q

Give the formula of the following molecular ions:

  1. NItrate
  2. Carbonate
  3. Sulfate
  4. Hydroxide
  5. Ammonium
  6. Zinc ion
  7. Silver ion
A
  1. NItrate = NO3 ^1-
  2. Carbonate = CO3 ^ 2-
  3. Sulfate = SO4 ^2-
  4. Hydroxide = OH ^1-
  5. Ammonium = NH4 ^1+
  6. Zinc ion = Zn ^2+
  7. Silver ion = Ag ^1+
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16
Q

What are salts?

A

Salts are ionic compounds.

Solid salts have a lattice of +ve and -ve ions.

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17
Q

What does a hydrated salt tell you?

A

It has waters of crystallisation attached to it.

18
Q

What is an anhydrous salt?

A

A salt that does not contain waters of crystallisation.

19
Q

How do you calculate the number of waters of crystallisation and formula of a hydrated salt.

A
  1. Find mols of water lost.
  2. Find mols of anhydrous salt.
  3. Calculate ratio of mols in anhydrous salt to mols of water in the form 1:n
20
Q

?What is the main difference between acids and bases

A

Acids are proton (H+) donors

Bases are proton (H+) acceptors.

21
Q

Give the name and formula of 4 common acids.

A

Hydrochloric acid HCl
Sulfuric acid H2SO4
Nitric acid HNO3
Ethanoic acid CH3COOH

22
Q

Give the name and formula of 3 common bases.

A

Sodium Hydroxide NaOH
Potassium Hydroxide KOH
Ammonia NH3

23
Q

When acids and bases react, how is water formed?

A

H+ ions released by the acid and OH- ions released by the base combine to form
OH- + H+ —> H20

24
Q

When acids and bases react, how is the salt formed?

A

When the H+ ions in the acid are replaced by metal ions or ammonium ions from the alkali
HCl + KOH —> KCl + H2O

25
Q

Describe the set up of equipment for performing a titration.

A

Measure out the alkali in a pipette to the line.
Let the alkali drop down into the conical flask and add an indicator.
Put the conical flask underneath a burette containing the acid, which allows you to add the acid drop by drop.

26
Q

Describe the procedure of doing a titration.

A
  1. First do a rough titration, to get an idea of the end point.
  2. Do an accurate titration, run the acid within 2cm^3 of the endpoint, then add the acid dropwise (drop by drop)
  3. Calculate the titre ( final reading - initial reading)
  4. Repeat the titration and calculate a mean, ignoring any anomalous results.
  5. Remember to wash out the conical flask, to remove any acid or alkali.
27
Q

How can you make a titration accurate?

A

When taking a reading from a burette, you should read from the bottom of the meniscus.

28
Q

What is an analyte?

A

Solution of unknown concentration.

29
Q

What is a standard solution?

A

Solution with a known concentration. Made by dissolving a known amount of solid in a known amount of water.

30
Q

How do you make up a standard solution?

A
  1. Using a precise balance, weigh out the required mass of solid.
  2. Transfer to a beaker. Use distilled water to wash and bits of solid from the watch glass.
  3. Add water to completely dissolve the solid. Use a glass rod to stir the solution.
  4. Once dissolved, transfer into a volumetric flask.
  5. Fill volumetric flask up to graduation line.
  6. Put lid on the flask and turn in over to thoroughly mix it.
31
Q

Give the equation linking mols, concentration and volume.

A

mols = conc x vol

32
Q

Give the equation for % yield.

A

Actual yield / theoretical yield x 100

MOLS

33
Q

Give the equation for Atom Economy.

A

Mr of desired product / Mr of all products x 100

34
Q

Give an example of a reaction which has a 100% Atom economy.

A

Addition reaction, as only 1 product is made.

C2H4 + H2 —> C2H6

35
Q

What does % yield tell you?

A

It tells you how wasteful the process is.

36
Q

What does Atom Economy tell you?

A

Tells you the sustainability of reactions.

37
Q

What is the oxidation number of Oxygen?

A

-2

38
Q

What is the oxidation number of Hydrogen?

A

+1

39
Q

What is oxidation?

A

Loss of electrons

40
Q

What is reduction?

A

Gain of electrons.

41
Q

What do oxidising agents do?

A

They accept electrons and get reduced.

42
Q

What do reducing agents do?

A

They donate electrons and get oxidised.

x A-level Chem (13 decks)

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