section 1 Principles of chemistry part 2 Flashcards

1
Q

what are isotopes?

A

Different atomic forms of the same element
With the same number of protons
But different number of neutrons

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2
Q

what is the equation for relative atomic mass?

A

(rel. mass x rel. abundance of isotope 1) + (rel. mass x rel. abundance of isotope 2) / the sum of the rel. abundances

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3
Q

what is the relative formula mass of H2O?

A

2 + 16 = 18

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4
Q

what is the empirical formula?

A

smallest whole number ratio of atoms in a compound

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5
Q

what is the molecular formula?

A

actual number of atoms in a compound

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6
Q

what is Avogadro constant?

A

moles 6.023x10(23)

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7
Q

whats the equation for number of moles?

A

mass in g divided by the relative formula mass

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8
Q

what is a solid salt containing water of crystallization?

A

hydrated

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9
Q

what is an anhydrous salt?

A

a salt without water of crystallization

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10
Q

what are the 2 equations to find volume using mole?

A
volume = moles of gas x 24
volume = (mas of gas/ relative formula mass) x100
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11
Q

what is concentration measured in?

A

moles per dm3

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12
Q

what is the equation for concentration?

A

number of moles/volume

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13
Q

electric current is ………………………

A

A flow of electrons or ions

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14
Q

when do ionic compounds conduct?why?

A

molten or in solution

electrons free to move

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15
Q

do covalent compounds conduct electricity?

A

no

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16
Q

why are metals good conductors?

A

they have a sea of delocalised electrons to carry an electrical current

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17
Q

why are metals malleable?

A

layers of atoms can slide over each other

18
Q

electrolysis is used to …………………..

A

make new substances

19
Q

what is an electrolyte?

A

a liquid that conducts electricity

20
Q

what is the name of the positive rod?

A

anode

21
Q

what is the name of the negative rod?

A

catode

22
Q

which way do the electrons flow?

A

from the anode (+) to the cathode (-)

23
Q

how many coulombs of charge is a faraday?

A

96 500

24
Q

What is avogadros law?

A

One mole of any gas occupies 24dm3 at room temperature and pressure

25
Q

What are the two equations for volume in dm3?

A

Moles of gas x 24

Mass of gas / Mr of gas x 24

26
Q

How do you calculate the volumes in a reaction if you know the masses?

A

Find the reacting mass

Use the formula to find the volume

27
Q

What happens in electrolysis of aqueous solutions?

A

Cathode: If H+ ions and metal ions are present, hydrogen gas will be produced if the metal ions are more reactive than the H+ ions, if the metal ions are less reactive, a solid layer of the pure metal will be produced

Anode: if OH- and halide ions are present, then those molecules will be formed, if not oxygen will form

28
Q

What happens in the electrolysis of sulfuric acid?

A

Contains SO4(2-), H+2, OH- ions

Hydrogen ions accept electrons so at the cathode hydrogen is produced: 2H+ + 2e- ➡️H2

Hydroxide ions lose electrons more easily than sulfate ions, so at the anode oxygen and water are produced: 4OH- ➡️ O2 + 2H2O + 4e-

29
Q

What happens in the electrolysis of sodium chloride?

A

Contains Na+, Cl-, OH-, H+

Hydrogen ions accept electrons so hydrogen gas is produced at the cathode: 2H+ + 2e- ……… H2

Chloride ion lose electrons more easily than hydroxide ions so chlorine gas is produced: 2Cl- ……… Cl2 + 2e-

30
Q

What happens in the electrolysis of copper sulfate?

A

Contains Cu+2, SO4(2-), H+, OH-

Copper ions accept electrons more easily than hydrogen ions so at the cathode copper metal is produced: Cu+2 + 2e- ……. Cu

Hydroxide ions lose electrons more easily than sulfate ions so at the anode oxygen and water are produced: 4OH- ……… O2 + 2H2O + 4e-

31
Q

How can the number of electrons transferred in electrolysis (to therefore increase the yield) be increased?

A

Electrolysing for a longer time

Increasing the current

32
Q

One faraday contains

A

One mole of electrons

33
Q

96500 coulombs is

A

One faraday

34
Q

What is the equation for charge

A

Current x time

I x t

35
Q

How do you calculate the masses for electrolysis?

A
  1. Write out the balanced half-equation for the reaction at the electrode with the element you want
  2. Calculate the faradays (Q / 96500) by calculating the charge (Q = I x t) first
  3. Calculate the number of moles produced (One mole = one f, but be careful as look at how many electrons are added in half equation, if 2 or any number apart from one, divide faradays by 2 or that number to get no of moles)
  4. Write in the Mr values from the periodic table to work out the mass (m = n x Mr) (Mr is the top number on each element of the periodic table).
36
Q

What does oxidised mean?

A

Loss of electrons.

37
Q

What does reduced mean?

A

Gain of electrons.

38
Q

What does a redox reaction mean?

A

When oxidation and reduction has both happened equally.

39
Q

The breaking of bonds is …………

And the making of bonds is …………

A

Endothermic

Exothermic.

40
Q

What are the 3 steps for calculating masses?

A

Wrote the balanced equation
Work out Mr of bits you want and divide them by the balancing number in the equation
Divide to get one then multiply to get all

41
Q

What is the equation for percentage yield?

A

Actual yield(grams)/ theoretical yield(grams) x 100

42
Q

What is room temperature and pressure?

A

25 degrees

1 atmosphere