Chapter 3 : The mole concept, chemical formula and equation/ stoichiometry IGCSE

Question 1

How should i convertdm3 to cm3?

Answer 1

*1000

Question 2

to get mole from :
-quantity
-volume
- mass
what do u do?

Answer 2

divide!!!

Question 3

List the cations that you need to remember… (13)

Answer 3

Potassium ion k+
Sodium ion Na+
Calcium ion Ca 2+
Magnesium ion Mg 2+
Aluminium ion Al 3+
Zinc ion Zn 2+
Iron (ii) ion Fe 2+
iron(iii) ion Fe 3+
Lead (ii) ion Pb 2+
Hydrogen ion H+
Copper (ii) ion Cu 2+
Silver ion Ag +
Ammonium ion NH4 +

Question 4

List the Anions you need to remember (9)

Answer 4

Fluoride ion F-
Chloride ion Cl-
Bromide ion Br-
Iodide ion I-
Sulphate ion SO4 -
Nitrate ion NO3 -
Hydroxide ion OH-
Oxide ion O 2-
Carbonate ion CO3 2-

Question 5

Define molecular formula of a compound (IGCSE)

Answer 5

Molecular formula of a coumpound is
the number and type of different atoms in one molecule.

Question 6

Define emprical formula of a compound

Answer 6

Emprical formula of a compounds is the SIMPLEST whole number RATIO of the different atoms or ions in a compound.

Question 7

what is the formula for ammonium?

Answer 7

NH4 +

Question 8

What is the formula for carbonate?

Answer 8

CO3 2-

Question 9

What is the formula for Hydroxide

Answer 9

OH -

Question 10

What is the formula for Hydrogen carbonate?

Answer 10

HCO3 -

Question 11

What is the formula for Nitrate?

Answer 11

c

Question 12

What is the formula for sulphate?

Answer 12

SO4 2-

Question 13

Explain how to find: the formula of ionic compounds. (3)

Answer 13

1) Write elements with charges
2) Drop and swap charges
3) Write the final formula

Question 14

State the 4 state symbols.

Answer 14

• Solid (s)
• Gas (g)
• Liquid (l)
• Aqueous (aq)

Question 15

State the valency of each group

Answer 15

State the valency of each group

Question 16

Explain how to find the formula for covalent compound (4)

Answer 16

1) Write the symbol of theelement
2) Write the valencies below the symbols
3) Drop and swap valences
4) Write the final formula

Question 17

Explain how to find ionic compound (2)

Answer 17

1) Write out all ions present
2) Cross out all ions that remained the same

Question 18

There are a few formulas that cannot be predicted:
What are they? (4)

Answer 18

Hydrochloric acid = HCl
Nitric acid = HNO3
Ethanoic acid = CH3COOH
Ammonia = NH3

Question 19

What is the calculation using chemical equation to get what the question is asking? (SPM)
(5)
clue:
includes mole

Answer 19

1) Write a balanced chemical equation.
- (when it asks questions with many compounds like a react with b and becomes c)

2) Identify and underline.
- what we have, what we want

3) Convert what we have into mole.

4) By using MOLE RATIO
- refer to number in front of chemical formula

5) Convert mole to what you want!

Question 20

What should you do if a question mentions combustion?

Answer 20

include + O2

Question 21

What should you do if a question meantions heating?

Answer 21

nothing you silly goose!!

Question 22

Define Relative Atomic Mass Ar (IGCSE)

Answer 22

Relative Atomic Mass Ar :
“The average MASS of the isotopes of an element compared to 1/12th of the mass of an atom of 12C.”

Question 23

Define Relative Molecular Mass Mr (IGCSE)

Answer 23

Relative Molecular Mass Mr :
“ The sum of the relative Atomic Mass. “

Question 24

What is the Relative Formula Mass Mr used for? (IGCSE)

Answer 24

It is used for ionic compounds!!!

Question 25

Define Mole.

Answer 25

Mole :
“ the UNIT of substances. It contains 6.02 * 10^23”

Question 26

Define Avogrado’s constant.

Answer 26

Avogrado’s constant :
“ 6.02 * 10^23 “

Question 27

How much volume does 1 mole occupy at r.t.p?

Answer 27

1 mole occupies a volume of 24dm3 (24000cm3) at room temp. & pressure.

Question 28

What should you add if an element is burnt?

Answer 28

+ O2

Question 29

How much does 1 mole occupy at s.t.p?

Answer 29

22.4dm3 (22400cm3)