c4 Flashcards

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1
Q

whats the formula for the number of moles

A

moles=mass(g) / Mr

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2
Q

whats the formula for working out mass (g)

A

mass=moles x Mr

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3
Q

what does Mr stand for

A

reltive formula mass

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4
Q

how do you figure out percentage mass

A

you find out the relative formula mass then divide the number by the relative formula mass

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5
Q

tell me the definition of yield

A

the mass of product that a chemical reaction produces

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6
Q

whats the equation of percentage yield

A

actual mass of product produced
——————————— x100
maximum theoretical mass of product possible

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7
Q

factors that may affect percentage yield

A

> the reaction may be reversible

> some of the product may be lost or left in the apparatus

> the reactants might not be pure

> some reactants might react to give unexcepted or unwanted products in alternative reactions

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8
Q

whats the formula for percentage atom economy

A

relative formula mass of the desired product from equation
——————————— x100
sum of the relative formula masses of the reactants from equation

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9
Q

why is it important to maximise atom economy in industrial processes

A

to conserve the earths resources and minimise population

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10
Q

how is atom economy usually expressed

A

as a percentage (%)

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11
Q

whats the formula for concentration for dm^3

A

amount of solute (g) /
volume of solution (dm^3)

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12
Q

what unit is a volume of solution normally

A

dm^3

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13
Q

whats the formula for concentration for cm^3

A

amount of solute (g)
—————————– x1000
volume of solution (cm^3)

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14
Q

whats the definition of a balanced equation

A

a symbol equation in which there are equal numbers numbers of each type of atom on either side of the equation

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15
Q

whats the formula for the number of moles in a gas for dm^3

A

volume of gas (dm^3)/
24dm^3

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16
Q

whats the formula for the number of moles in a gas for cm^3

A

volume of gas (dm^3)/
24,000cm^3

17
Q

why does mass increase during a reaction

A

It has gained oxygen, and this has caused the increase in mass. This is why this is called an oxidation reaction.

18
Q

after heating the crucible again what should you do to make sure the reaction is complete

A

Heat again, this time for 10 minutes, then cool and weigh as before. If the crucible, cover, and sample weigh the same, then we can be reasonably confident that the reaction is complete