amount of substance

Question 1

what is the relative atomic mass?

Answer 1

the average mass of the isotopes for an element on a scale of which a carbon-12 atom has a mass of exactly 12 units

Question 2

what is the equation for the relative atomic mass of an element?

Answer 2

average mass of one atom of an element x 12 // mass of one atom of C12

Question 3

what is the definition of relative molecular mass or Mr?

Answer 3

the average mass of one molecule on a scale of which a carbon- 12 atom has a mass of exactly 12 units

Question 4

what is the equation for the relative molecular mass of a molecule?

Answer 4

average mass of a molecule x 12 // mass of one atom of C12

Question 5

when is the term relative formula mass used?

Answer 5

for ionic compounds because they don’t exist as molecules

Question 6

what is the avogadro’s constant?

Answer 6

the number of atoms in 12g of Carbon 12

Question 7

what is a mole?

Answer 7

the amount of substance that contains 6.022 x 10^23 particles

Question 8

what is the value of avogadro’s constant?

Answer 8

6.022 x 10^23

Question 9

what is the moles equation?

Answer 9

moles= mass/Mr (mass of one mole)

Question 10

what does the concentration of a solution tell us?

Answer 10

how much solute is present in a known volume of solution

Question 11

what are concentrations of solutions measured in?

Answer 11

mol/dm^3

Question 12

what is the equation for how to work out the number of moles in a solution?

Answer 12

number of moles in solution=

concentration(mol/dm^3) x volume (dm3)

Question 13

what is Boyle’s law?

Answer 13

the product of pressure and volume is constant as long as the temperature remains constant

pressure x volume = constant

Question 14

what is Charles’ law?

Answer 14

volume is proportional to temperature as long as pressure remains constant

volume/ temp = constant

Question 15

what is Gay-Lussac’s law (also called the constant volume law)?

Answer 15

pressure is proportional to temperature as long as volume remains constant

pressure/ temp = constant

Question 16

what does combining Boyle’s, Charles’ and Gay- Lussac’s laws result in?

Answer 16

pressure x volume/ temperature = constant for a fixed mass of gas

Question 17

what is the ideal gas equation in words?

Answer 17

pressure x volume = number of moles x gas constant x temperature

Question 18

what is the ideal gas equation in symbols?

Answer 18

P x V = n x R x T

Question 19

what is the ideal gas equation in units?

Answer 19

Pa x m^3 = mol x JK^-1mol^-1 x K

Question 20

what is always the value of R (gas constant)?

Answer 20

8.31 JK^-1mol^-1 (always given this)

Question 21

what unit does temperature always need to be changed to in ideal gas equations?

Answer 21

Kelvin

Question 22

on the kelvin scale, where is 0 Degrees Celsius?

Answer 22

273k

so you always add 273 to the temp

Question 23

what is the empirical formula?

Answer 23

the formula that represents the simplest whole number ratio of the atoms of each element present in a compound