Equations

Question 1

density

Answer 1

mass/volume

Question 2

percentage yield

Answer 2

actual yield/ theoretical yield x 100

Question 3

percentage composition by mass

Answer 3

mass of you what you want to know/ mass of the whole thing (including what you want to know)

Question 4

percentage atom economy

Answer 4

useful products/ mass of all reactants

Question 5

percentage uncertainty

Answer 5

uncertainty/ measurement made from apparatus

Question 6

energy change (J)

Answer 6

= mass of solution (g) x heat capacity (J/g/K) x temperature change (K)

Question 7

enthalpy change

Answer 7

Break - make

Question 8

enthalpy change of a reaction (combustion)

Answer 8

enthalpy of reactants - products

Question 9

enthalpy change of a reaction (formation)

Answer 9

enthalpy of products - reactants

Question 10

Kc

Answer 10

Products / reactants (Kc only changes with temperature)

Question 11

standard conditions for temperature

Answer 11

25 degrees Celsius or 298K

Question 12

standard conditions for pressure

Answer 12

100Kpa

Question 13

relative atomic mass

Answer 13

isotopic mass x abundance / 100

Question 14

moles

Answer 14

mass/Mr

Question 15

concentration (moles)

Answer 15

moles/volume

Question 16

concentration (mass)

Answer 16

mass/volume

Question 17

pressure, volume, temperature, moles and R formula

Answer 17

P (pa) V (m3) =n (moles) R (constant) T (K)
(remember to convert m3 you need to times by the converter cubed!)

Question 18

volume equation at room temperature

Answer 18

moles x 24

Question 19

number of particles equation

Answer 19

moles x Avogadro’s constant

(6.02x10^23)