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AQA GCSE Chemistry > C3- Quantative Chemistry > Flashcards

C3- Quantative Chemistry Flashcards

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1
Q

Mass number

A

The total number of protons and neutrons

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2
Q

Atomic number

A

The number of protons or the number of electrons

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3
Q

Relative atomic mass

A

The number of protons or the number of electrons

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4
Q

State the law of conservation of mass?

A

No atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

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5
Q

What is relative formula mass (Mr)?

A

The relative formula mass (Mr) of a compound is the sum of the relative atomic masses of the atoms in the numbers shown in the formula.

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6
Q

Why may some reactions appear to have a change in mass?

A

Some reactions may appear to involve a change in mass but this can usually be explained because a reactant or product is a gas and its mass has not been taken into account.

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7
Q

What is the Avogadro constant?

A

The number of atoms, molecules or ions in a mole of a given
substance is the Avogadro constant. The value of the Avogadro constant is 6.02 x 1023 per mole.

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8
Q

What is a limiting reactant?

A

The reactant that is completely used up is called the limiting reactant because it limits the amount of products.

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9
Q

Percentage yield equation?

A

% Yield = (Mass of product actually made / Maximum theoretical mass of product) × 100

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10
Q

What is atom economy?

A

The atom economy (atom utilisation) is a measure of the amount of starting materials that end up as useful products.

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11
Q

Percentage atom economy equation?

A

(Relative formula mass of desired product / Sum of relative formula masses of all reactants from equation) × 100

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12
Q

What is the volume of 1 mole of gas at room temperature?

A

The volume of one mole of any gas at room temperature and pressure (20C and 1 atmosphere pressure) is 24 dm3

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13
Q

What is electrolysis?

A

Electrolysis breaks down ionic compounds (salts) into their element using electricity.

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14
Q

Ions must be _ for electrolysis to work?

A

free to move

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15
Q

Cations?

A

+ ions (formed by metals)

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16
Q

Anions?

A
  • ions (formed by non-metals)
17
Q

3 things electrolysis is used for?

A

To extract reactive metals from their ores, to purify metals, electroplating.

18
Q

How is aluminum extracted from it’s ore?

A

Bauxite contains alumina -> it’s refined to produce ammonia -> ammonia is melted with cryolite to lower it’s melting point -> using electrolysis aluminium is formed.

19
Q

What are the 2 rules for electrolysis?

A
  • At the cathode, the ion of the least reactive element will be discharged.
  • At the anode, if a halide (group 7) is present that’s the one that gets discharged. If there is not one present the hydroxide ion is discharged, and oxygen is produced.
20
Q

What is an ore?

A

An ore is a material containing enough metal for it to be economically worth extracting.

21
Q

Equation linking moles, mass and formula mass?

A

Moles (mol) = mass (g) / formula or atomic mass (g/mol)

22
Q

Equation linking concentration, amount of solute, and volume of solution.

A

Conc. = amount of solute (moles) / volume of solution

23
Q

Why is a higher atom economy desired?

A

It’s more sustainable, less waste products and therefore less pollution, use fewer raw materials (natural resources) and therefore less energy.

24
Q

Why is 100% yield unattainable?

A

-Reversible reactions (doesn’t reach completion)
-Errors can be made
-Unexpected reactions occur (reactions are not 100% pure)
-Product is lost during separation or transfer

25
Q

What is uncertainty?

A

When measuring quantities, there is always some degree of error known as uncertainty.

26
Q

What is resolution?

A

The smallest measurement that a piece of equipment can measure.

27
Q

What is the uncertainty of an analogue measurement?

A

Half the resolution.

28
Q

What is the uncertainty of a digital measurement?

A

Half the last digit shown on it’s display.

29
Q

What is the uncertainty for a set of repeat measurements?

A

+- half the range

AQA GCSE Chemistry (4 decks)

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