C3.1 - Introducing chemical reactions

Question 1

Why are the formulae of metal elements always written as empirical formulae?

Answer 1

• because they exist as giant metallic lattices
• numbers in the formula would be too big
  ie. C 432625 H 736765 N 63910

Question 2

are the non-metal elemis in group 0 diatomic atoms?

Answer 2

no, they exist as individual atoms

Question 3

what is special about the elements in group 7?

Answer 3

they are all diatomic (expect astatine?????)

Question 4

list all the diatomic molecules (7)

Answer 4

Hydrogen
Oxygen
Nitrogen 
Fluorine 
Chlorine
Bromine
Iodine

Question 5

-

Answer 5

-

Question 6

give examples of a simple covalent compound

Answer 6

• Carbon dioxide
• methane
• water

Question 7

explain (in terms of particles), why the mass of the solid increases when copper is heated in the air

Answer 7

• copper atoms combine with oxygen atoms in the air
• forms a copper oxide (chemical reaction)
• therefore, mass increases since the solid is made of copper atoms and oxygen atoms

Question 8

explain what is meant by the law of conservation of mass

Answer 8

the principle that states that the total mass stays the same during a chemical reaction, because atoms are not created or destroyed

Question 9

what is a non-enclosed system?

Answer 9

when substances can leave or enter the reaction mixture (usually in an open container)

Question 10

what is a closed system?

Answer 10

• a container where no substances can enter or leave during the reaction

Question 11

what do half equations show?

Answer 11

• the change that happens to one reactant in a chemical reaction

Question 12

define the term ‘mole’

Answer 12

the amount of any substance that contains the same number of entities as there are atoms in 12.0g of carbon-12

Question 13

define the term ‘Avogadro’s constant’

Answer 13

the number of entities in 1 mole, equal to the number of atoms in 12 grams of Carbon-12

Question 14

what terms are the same as molar mass?

Answer 14

• relative atomic mass

- relative formula mass

Question 15

what is molar mass measured in?

Answer 15

grams per mole (g/mol)

Question 16

how do you figure out the possbible uncertainty of a volume?

Answer 16

same way as bound (add half, minus half)

Question 17

what is the equation to calculate the mass of a substance

Answer 17

mass (g)= molar mass (g/mol) x number of moles (mol)

Question 18

What is limiting reactant

explain the effect of a limiting amount of a reactant

Answer 18

(((- it determines the amount of product made))))AD

Limiting reactant is the reactant that is used up first / limiting reactant has fewer moles (than other reactants)

Idea that reaction stops once limiting reactant is consumed or used up

Question 19

what does a stoichiometry describe?

Answer 19

the relative amounts of each substance involved in a reaction

Question 20

what is the charge of ammonium ions?

Answer 20

+
NH
4

Question 21

what is the charge on a silver ion?

Answer 21

Ag+

Question 22

what is the charge on a barium ion?

Answer 22

2+

Ba

Question 23

what is the charge on a aluminium ion?

Answer 23

3+

Al

Question 24

what is the charge on a hydroxide ion?

Answer 24

OH-

Question 25

what is the charge on a nitrate ion?

Answer 25

-
NO
3

Question 26

what is the charge on an oxide ion?

Answer 26

2-

O

Question 27

what is the charge on a carbonate ion?

Answer 27

2-
CO
3

Question 28

what is the charge on a sulfate ion?

Answer 28

2-
SO
4

Question 29

what do state symbols show?

Answer 29

the physical state of each substance in a chemical equation

Question 30

what is avogadro’s constant (number)?

Answer 30

6.02 x 10^23

Question 31

what is a limiting reactant?

Answer 31

The reactant that is completely used up

Question 32

What’s a precipitation reaction

Answer 32

In these reactions, an insoluble product or precipitate forms when two solutions are mixed

Question 33

Do you know what an ionic equation and net ionic equation is?

Answer 33

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