C3

Question 1

Whats the law of conservation of mass

Answer 1

mass is not lost or gained during a chemical reaction

Question 2

why might mass appear to change in a chemical reaction

Answer 2

if a gas is involved and escapes or is added from the air

Question 3

what is the relative formula mass

Answer 3

the sum of relative atomic masses of all atoms in a compound

Question 4

what is a mole

Answer 4

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

Question 5

how do you calculate the number of moles

Answer 5

moles=mass/mr

Question 6

whats the formula to calculate mass from moles

Answer 6

mass=molesx mr

Question 7

whats the limiting reactant

Answer 7

the reactant that is completely used up first and limits the amount of product formed

Question 8

whats the excess reactant

Answer 8

the reactant that is not completely used up in reaction

Question 9

whats conectration

Answer 9

the amount of solute dissolved in a certain volume of solution

Question 10

how do you calculate concentration

Answer 10

concentration=mass of solute/volume of soloution

Question 11

how do you calculate the volume of gas

Answer 11

molesx24

Question 12

why is percentage yield never 100%

Answer 12

due to loss of product,side reaction or incomplete reactions