4.4 Moles 1

Question 1

What is relative formula mass?

Answer 1

mass of a formula unit

Question 2

What is the equation for RFM?

Answer 2

adding the relative atomic masses

Question 3

What does percentage by mass show?

Answer 3

mass of an element in a substance

Question 4

What is the equation for percentage by mass?

Answer 4

mass of element / RFM x 100

Question 5

What is a mole?

Answer 5

unit of amount of a substance

Question 6

What is the equation for moles?

Answer 6

moles = mass/RFM

Question 7

What is mass measured in?

Answer 7

grams (g)

Question 8

What is the empirical formula?

Answer 8

simplest mole ratio of elements in a substance

Question 9

What is molecular formula?

Answer 9

actual number of atoms in a molecule

Question 10

What is water of crystillisation?

Answer 10

crystals contain water trapped inside in a fixed mole ratio

Question 11

What is the equation for water of crystillisation?

Answer 11

CuSO4 . 5H2O

Question 12

What happens when salt crystals are heated?

Answer 12

lose their water

Question 13

What is the hydrated copper sulphate broken down into when heated?

Answer 13

anhydrous copper sulphate and water vapour

Question 14

What is the limiting substance?

Answer 14

not enough of substance for reaction

Question 15

What is the excess substance?

Answer 15

too much of substance for reaction

Question 16

What is the equation for percentage yield?

Answer 16

% yield = experimental / theoretical x 100

Question 17

Where does the experimental value come from in percentage yield?

Answer 17

from experiment

Question 18

Where does the theoretical value come from in percentage yield?

Answer 18

from calculation