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A Level Chemistry > Chapter 3 - Amount of substance > Flashcards

Chapter 3 - Amount of substance Flashcards

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1
Q

What is the Avogadro constant?

A

6.02 x 10^23

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2
Q

The equation for the number of moles

A

Mass / Mr

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3
Q

What is the molar mass?

A

The mass of one mole of something

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4
Q

How to work out the number of moles of something?

A

Multiply the number of moles by the Avogadro constant

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5
Q

What is the molar gas volume?

A

The space that one mole of a gas occupies at room temperature and pressure

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6
Q

The equation for the number of moles of a gas

A

Volume (dm3) / 24 dm^3

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7
Q

What is the empirical formula

A

The smallest whole number of atoms of each element in a compound

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8
Q

What is the molecular formula?

A

The actual number of atoms of each element in a compound

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9
Q

Formula of nitrate

A

NO3 -

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10
Q

Formula of carbonate

A

CO3 2-

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11
Q

Formula of sulfate

A

SO4 2-

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12
Q

Formula of hydroxide

A

OH-

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13
Q

Formula of ammonia

A

NH4 +

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14
Q

Formula of zinc

A

Zn 2+

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15
Q

Formula of silver

A

Ag +

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16
Q

What is important to remember about ionic compounds?

A

The charges always balance

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17
Q

What is produced when acids and bases react?

A

Water and a salt

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18
Q

What is the water of crystallisation?

A

The water in an ionic lattice

19
Q

How to work out the water of crystallisation?

A

Use COMMA R (see cards)

20
Q

What is the empirical formula of a compound?

A

The smallest whole number ratio of atoms in a compound

21
Q

What is the molecular formula of a compound?

A

The actual number of atoms of each element in a molecule

22
Q

How to calculate the empirical and molecular formula?

A

Use EMMA and COMMA R

23
Q

What is relative molecular mass?

A

The mass of a molecule compared to the mass of an atom of carbon 12

24
Q

What is the relative formula mass?

A

Compares the mass of a formula unit with the mass of an atom of carbon-12

25
Q

What is the water of crystallisation?

A

The water molecules that are part of the crystalline structure of a salt

26
Q

Assumptions made when using experimental formula (2)

A

All of the water has been lost

No further decomposition

27
Q

What is a polyprotic acid?

A

One which donates more than one proton

28
Q

What is the ideal gas equation?

A

Pressure x volume = moles x ideal gas constant x temperature

29
Q

What is the ideal gas constant?

A

8.31 Jmol-1K-1

30
Q

How to go from cm3 to m3?

A

x10(-6)

31
Q

How to go from dm3 to m3?

A

x10(-3)

32
Q

How to go from Celsius to Kelvin?

A

+273

33
Q

How to go from kPa to Pa?

A

x10(3)

34
Q

What is stoichiometry?

A

The ratio of the moles of each reacting substance

35
Q

Reasons why maximum theoretical yield is rarely reached (3)

A

The reaction may not have gone to completion
Side reactions may have taken place as well
Purifying the product may result in the loss of some of it

36
Q

Equation for percentage yield

A

(Actual yield/theoretical yield) x 100

37
Q

What is the limiting reagent?

A

The one that will be used up first and stop the reaction

38
Q

How to find the limiting reagent?

A

Work out the moles of each reagent and compare with the equation

39
Q

What is atom economy?

A

The proportion of atoms in the reagents that end up as the products

40
Q

Equation for atom economy

A

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

41
Q

What is a standard solution?

A

One with a known concentration

42
Q

How would you work out the formula of a hydrated salt?

A

1) Weigh an empty crucible
2) Add the hydrated salt into it and weigh again
3) Heat the crucible and contents strongly for about 3 minutes
4) After leaving to cool, reweigh the crucible and remaining salt

43
Q

Why aren’t experiments to determine the water of crystallisation always accurate?

A

They assume that all of the water has been lost and that there is no further decomposition after heating

44
Q

What is the ideal gas equation?

A

pV = nRT

A Level Chemistry (29 decks)

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