That no atoms are lost or made during a chemical reaction
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2
What is the relative formula mass of a compound?
The sum of the relative atomic masses of the atoms in the compound
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3
Some reactions can appear to involve a change in mass. What is a common explanation for this?
A product is a gas whose mass has not been taken into account
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4
What are chemical amounts measured in?
Moles
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5
What is the symbol for the unit mole?
Mol
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6
One mole of a substance contains how many atoms?
6.02 x10^23 atoms
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7
What is Avogadro's Constant?
6.02 x10^23 atoms
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8
What do we call the reactant that is completely used up in a reaction?
The limiting reactant
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9
What is the unit for measuring the concentration of a solution?
g/dm3
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10
What is the equation to work out the concentration of a solution?
Concentration \= Mass/Volume
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11
Why is not always possible to obtain the calculated amount of a product?
the reaction may not go to completion because it is reversible some of the product may be lost when it is separated from the reaction mixture some of the reactants may react in ways different to the expected reaction
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12
What is the amount of a product obtained as known?
Yield
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13
What do we call the compression of the maximum theoretical amount to obtained amount?
Percentage Yield
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14
What is the equation to calculate percentage yield?
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15
What is atom economy (atom utilisation)?
A measure of the amount of starting materials that end up as useful products
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16
What is atom economy important for?
Sustainable development Economic reasons
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17
What is the equation to calculate the percentage atom economy of a reaction?
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18
What does a reaction pathway describe?
The sequence of reactions needed to produce a desired product
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19
What factiors will be involved in deciding on the pathway for a chosen product?
Percentage yield Atom economy Rate of reaction Equilibrium position Usefulness of by-products
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20
What can the concentration of a solution be measured in?
mol/dm3
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21
What can be calculated from a solution's concentration?
Amount of moles of solute Mass in grams of solute in a given volume of solution
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22
What do you need to know to be able to calculate the concentration of an unknown solution?
The volumes of the two solutions Concentration of one of the solutions
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23
What is the concentration of a solution in mol/dm3 related to?
The mass of the solute The volume of the solution
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24
What do equal amounts in moles of gases do when they occupy the same volume?
Temperature Pressure
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25
What is the volume of one mole of any gas at room temperature (20oC and 1 atmosphere pressure)?
24dm3
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What can be calculated from the balanced equation of a reaction?
The volumes of gaseous reactants and products
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27
What do you need to calculate the volume of gas at room temperature and pressure?
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