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M2:Chapter 3=> Amount Of Substances > 3.1-3.4 > Flashcards

3.1-3.4 Flashcards

1
Q

How are ions created

A
  • when electrons are transferred from one atom to another
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2
Q

How would you describe hydrated salts

A
  • salts with water
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3
Q

How would you describe anhydrous salts

A
  • salts without water
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4
Q

How would you describe water and how does this make it a good solvent

A
  • polar
  • this makes it a good solvent as the delta negative oxygen is attracted to the positive ions and the delta positive hydrogen is attracted to the negative ions
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5
Q

What is the term used to describe water molecules existing within crystal structures

A
  • water of crystallisation
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6
Q

How do we write an equation for every mole of salt you have for a certain number of moles of water of crystallisation

A

. XH2O

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7
Q

Describe the experiment that is carried out to work out the value of water crystallisation

A

1) heat the salt which removes the water from the crystals
2) and you are left with an anhydrous salt

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8
Q

1.88g of hydrates CaSO4.xH2O was heated until there was no more water of crystallisation was left in the sample. The mass of this anhydrous compound is 1.13g. Work out the value of x (the amount of water of crystallisation)

A

Moles of water of crystallisation= 5
CaSO4.5H2O

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9
Q

What do ionic equations show

A
  • the ions that are formed in solution and which particles are reacting
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10
Q

Define the term mole

A
  • a way of measuring the amount of a substance
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11
Q

What is Avogadro’s number

A

6.02 x 10 ^23

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12
Q

How many molecules is 1 mole of H2O

A

6.02 x 10^23 molecules of H2O

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13
Q

How many molecules is 1 mole of Fe

A

6.02 x 10^23 molecules of Fe

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14
Q

How do you calculate the number of particle in a substance

A

Using:
Avogadro’s number x number of moles

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15
Q

How many particles make up 0.67 moles of NH3

A

Avogadro’s number x Number of moles
=> 6.02 x 10^23 x 0.67
Number of particles= 4.03 x 10^23

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16
Q

How do you work out the number of moles

A

Mass/ Mr

17
Q

How do you calculate the number of moles of a substance in solution

A
  • from concentration & volume
18
Q

What is the formula for number of moles of a substance in solution

A

Concentration(moldm^-3) x Volume(dm^3)

19
Q

How do you convert from cm^3 to dm^3

A
  • divide by 1000
20
Q

What does the ideal gas equation end up showing

A
  • the number of moles in a specific volume of a gas
21
Q

What is the ideal gas equation

A

pV = nRT

=> p=pressure (Pa)
=> V=volume (m^3)
=> n=moles (moles)
=> R=gas constant (8.31 JK^-1mol^-1)
=> T=temperature (K)

22
Q

How do you convert from KPa to Pa

A
  • multiply by 1000
23
Q

How do you convert from cm^3 to m^3

A
  • divide by 1,000,000 (1 x 10^6)
24
Q

What are the standard conditions for reactions

A
  • 298K
  • 100kPa
25
Q

Calculate a theoretical mass from an equation:
How much CaO can be made when 34g of Ca is burnt completely in oxygen

A

47.6g

26
Q

What is the theoretical mass

A
  • the amount of product we make assuming NO products are lost and ALL reactants react fully
27
Q

Calculating a volume of a gas from an equation:
What volume of H2 is produced when 12g of potassium reacts with water at 100kPa of pressure and 298K. Gas constant is 8.31JK^-1mol^-1

A

Volume= 3.8 x 10^-3 m^3

28
Q

Define empirical formula

A
  • the simplest whole number ratio of elements in a compound
29
Q

A compound contains 23.3% of Magnesium, 30.7% of Sulfur and 46.0% oxygen. What is the empirical formula of this compound

A

MgSO3

30
Q

How do you work out the molecular formula from the empirical formula

A
  • work out the Mr of the empirical formula
  • divide by the Mr of the molecular formula
  • use the answer to that division to multiply all the atoms in the empirical formula
31
Q

A hydrocarbon combusts completely to make 0.845g of CO2 and 0.173g of H2O. What is the empirical formula of the hydrocarbon?

A

CH
* remember that the carbon is CO2 and the hydrogen in H2O can only come from the hydrocarbon

32
Q

What is the equation for percentage yield

A

Actual yield/ theoretical yield x 100

33
Q

In a reaction involving the complete combustion of calcium 32.6g of calcium oxide was produced. The theoretical mass is 47.6g. Calculate the percentage yield of this reaction.

A

Percentage yield= 68.5%

34
Q

Fill in the blank:
Percentage yield is _____ 100%

A

1) NEVER

35
Q

Why is percentage yield never 100%

A
  • because you loose some of your product when transferring it
  • not all reactants will have reacted
  • some of the product may escape if its a gas
  • may be impurities that may have reacted
36
Q

Define atom economy

A
  • how efficient a reaction is
37
Q

What is the equation for atom economy

A

Mr of desired product
________________________ X 100
Sum of Mr of all products

38
Q

Iron oxide (Fe2O3) can be reduced using carbon (coke) to make pure Iron and carbon dioxide. Calculate the atom economy in the extraction of Iron

A

Atom economy= 62.8%

39
Q

Why is high atom economy important

A
  • high atom economy means the raw materials are used more efficiently, which is more sustainable
  • high atom economy means less waste and so benefits the environment
  • high atom economy means less by product so less time and money spent separating them from the desired product

M2:Chapter 3=> Amount Of Substances (1 decks)

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