Formulas

Question 1

Balanced equation?

Answer 1

Shows the same number and type of atoms on each side of an equation.

Question 2

Gram formula mass?

Answer 2

• write formula (this is often done for you)
• determine number of atoms of each element
• use Data Book to find relative atomic masses (RAM)
• calculate total mass of substance.

Question 3

Example of formula mass

Answer 3

copper (II) carbonate 
CuCO3
1 x Cu = 1 x 64 = 64
1 x C = 1 x 12 = 12 3xO=3x16 =48
Gram formula mass = 124g

Question 4

Percentage composition ?

Answer 4

% Element = (mass of element / formula mass) x 100

Question 5

Example of percentage composition

Answer 5

potassium sulphate (K2SO4)
2 x K = 2 x 39 = 78 
1xS =1x32 = 32 
4 x O = 4 x 16 = 64
formula mass = 174 amu
%K = (78 / 174 ) x 100 = 44.8 %

Question 6

What is titration?

Answer 6

• practical method of using one chemical of known concentration to determine the unknown concentration of another.

Question 7

What is percentage composition?

Answer 7

The amount of a certain element as a percentage

Question 8

Titration formula?

Answer 8

concentration of acid X volume of acid X number of H+ ions= concentration of alkalai X volume of alkalai X number of OH- ions