National 5 Chemistry (UNIT 1)

Question 1

State how the progress of a chemical reaction can be measured.

Answer 1

• Changes in mass
• Changes in volume
• Changes in other quantities

Question 2

Describe how the rate of reaction can be increased.

Answer 2

• Increase the temperature
• Increase the concentration of a reactant
• Increasing the surface area
• Decrease particle size
• Use a catalyst

Question 3

State what is meant by the term ‘catalyst’.

Answer 3

A catalyst is a substance that speeds up a chemical reaction but can be recovered chemically unchanged at the end of the reaction.

Question 4

Over the course of a 5 minute reaction, 50g of CaC03 was lost. Calculate the rate of reaction showing appropriate units.

Answer 4

0.167 gs-1

Use the rate equation in the data booklet.
You must show the units in this question.

Question 5

Describe how the rate of a reaction can be shown to decrease over time.

Answer 5

Calculate the average rate at different stages of the reaction.

Question 6

Describe how elements in the Periodic Table are arranged.

Answer 6

• In order of increasing atomic number.

Question 7

Is magnesium a metal? Justify your answer.

Answer 7

Magnesium is a metal as it is on the left of the periodic table.

Question 8

What do elements in the same group have in common?

Answer 8

The same number of electrons in their outer energy levels. (outer electrons)

Question 9

What is the electron arrangement of hydrogen?

Answer 9

1

Question 10

State the charges on the sub-atomic particles of an atom.

Answer 10

Proton - 1+
Neutron - 0
Electron - 1-

Question 11

State the mass on the sub-atomic particles of an atom.

Answer 11

Proton - 1 amu
Neutron - 1 amu
Electron - 0 amu

Question 12

Fill in the gap:

In a neutral atom, the number of _____ is equal to the number of _____.

Answer 12

Proton/Electron (any order)

Question 13

Fill in the gap:

The mass number of an atom is equal to the number of _____ added to the number of _____.

Answer 13

Proton/Neutron (any order)

Question 14

State what is meant by the term ‘isotope’.

Answer 14

An atom with the same atomic number but different mass number/ same number of protons but different number of neutrons.

Question 15

State what is shown by nuclide notation for an ion.

Answer 15

• Mass number
• Atomic number
• Charge

Question 16

State what is meant by the term ‘relative atomic mass’.

Answer 16

• The average atomic mass for an element using the mass and proportion of each isotope for that element.

Question 17

Is the statement true or false:

Covalent bonds form between non-metal atoms.

Answer 17

True

Question 18

Explain how a covalent bond forms.

Answer 18

A covalent bond forms when two positive nuclei are held together by their common attraction for a shared pair of electrons.

Question 19

Draw a diagram showing all the outer electrons for NH3.

Answer 19

• Any diagram (petal diagram included) is suitable.

Question 20

State the diatomic molecules.

Answer 20

Use: Have No Fear Of Ice Cold Beer.

• Hydrogen
• Nitrogen
• Fluorine
• Oxygen
• Iodine
• Chlorine
• Bromine

Question 21

State the four shapes of simple covalent molecules.

Answer 21

• Linear
• Angular
• Trigonal pyramidal
• Tetrahedral

Question 22

True or false:

Only one bond can be formed between atoms.

Answer 22

False

More than one bond can form, leading to double or triple covalent bonds.

Question 23

State the two types of covalent substances.

Answer 23

• Discrete covalent molecular

- Covalent networks

Question 24

Explain the properties of covalent molecular substances.

Answer 24

• They have strong covalent bonds within the molecules and only weak attractions between the molecules.
• They have low melting and boiling points as only weak forces of attraction between the molecules are broken when a substance changes state.
• They do not conduct electricity because they do not have charged particles which are free to move.

Question 25

True or false: | Covalent molecular substances which are insoluble in water may dissolve in other solvents.

Answer 25

True.

Question 26

What is the difference between covalent molecular and covalent network substances in terms of bonding?

Answer 26

- Covalent molecular substances have weak intermolecular bonds but strong covalent bonds within the molecule. - Covalent network substances only have a strong network of covalent bonds within one giant structure.

Question 27

Fill in the gaps: Covalent network structures have very _____ melting and boiling points because the network of strong _____ _____ is not easily _____.

Answer 27

High/Covalent/Bonds/Broken

Question 28

True or false | Covalent network substances do not dissolve

Answer 28

True.

Question 29

Explain why covalent network substances do not conduct electricity.

Answer 29

- They do not have charged particles which are free to move. (DO NOT ACCEPT 'ions')

Question 30

Name one covalent substance which conducts electricity. Explain why this is the case.

Answer 30

- Graphite/Carbon because it has a sea of delocalised electrons, like metals, which are free to move.

Question 31

Explain how ions are formed.

Answer 31

Ions are formed when atoms lose or gain electrons to obtain the stable arrangement of a noble gas/a full outer electron shell.

Question 32

State the charge on a metal ion.

Answer 32

Positive.

Question 33

State the name of an equation to show the formation of ions through the loss or gain of electrons.

Answer 33

Ion-electron equations.

Question 34

State what is meant by the term 'ionic bond'.

Answer 34

- Ionic bonds are the electrostatic attraction between positive and negative ions.

Question 35

State the term used to describe the structure of an ionic compound.

Answer 35

Lattice.

Question 36

Explain the properties of ionic compounds.

Answer 36

- They have high melting and boiling points because strong ionic bonds must be broken in order to break the lattice. - They are soluble in water as the lattice structure breaks up allowing water molecules to surround the separated ions. - They conduct electricity when molten or in solution as the lattice structure breaks up allowing the ions to be free to move.

Question 37

State the elements present in copper sulfate.

Answer 37

- Copper - Sulfur - Oxygen

Question 38

Write the chemical formulae for copper nitrate.

Answer 38

Cu(NO3)2

Question 39

What do roman numerals indicate about an element?

Answer 39

Its valency.

Question 40

Fill in the gap: | The formula of a _____ _____ and any _____ substance gives the simplest ratio of each type of atom in a substance.

Answer 40

- Covalent network | - Ionic

Question 41

State the name of ions which contain more than one type of atom.

Answer 41

Group ions.

Question 42

Balance the following equation: | H2+O2 -) H2O the numbers should be small

Answer 42

2H2 + O2 -) 2H20 | The 2 in front of the hydrogens are big and the 2 behind the oxygen and hydrogen in water are small.

Question 43

What is the percentage composition of nitrogen in ammonia?

Answer 43

82.2% Working: NH3 GFM = (14+1+1+1) = 17g (14/17 x 100) = 82.2%

Question 44

True or false: | pH 7 is an acid.

Answer 44

False. It is a neutral solution.

Question 45

Write down the equation showing how water dissociates.

Answer 45

Correct 'disassociation of water' balanced equation.

Question 46

True or false: | The disassociation of water is reversible.

Answer 46

True.

Question 47

Describe the difference in terms of H+ and OH- ions between pH 1, 7, 9.

Answer 47

- pH 1 has a higher concentration of H+ ions than OH- ions. pH 7 has equal concentrations of H+ and OH- ions. pH 9 has higher concentrations of OH- ions than H+ ions.

Question 48

Fill in the gaps: Dilution of an alkaline solution with water will _____ the concentration of OH- ions and the pH will decrease towards pH __.

Answer 48

- Decrease | - 7

Question 49

Describe how acidic solutions are formed.

Answer 49

Soluble non-metal oxides dissolve in water.

Question 50

What term could be used to describe the following: - Metal oxides - Metal hydroxides - Metal carbonates - Ammonia

Answer 50

Bases

Question 51

What is always produced in a neutralisation reaction?

Answer 51

a salt and water.

Question 52

What type of salt does hydrochloric acid produce?

Answer 52

chloride salts.

Question 53

State what is meant by the term 'spectator ion'.

Answer 53

Ions that remain unchanged by the reaction.

Question 54

Open ended question practice: (3 marks) Using your knowledge of chemistry, explain how the concentration of a specific acid can be determined.

Answer 54

Possible things to mention: (response should cover at least 1 A4 page, with info, equations, drawings etc.) - Acid-base titration (drawing and description) - Standard solutions - Concordant values - n=CV - Balanced equations - Mole ratios - Indicators - Pipettes/burettes - Sample calculation

Question 55

Describe the preparation of a soluble salt.

Answer 55

- Do a titration. Once the volumes of acid and alkali have been noted, repeat the neutralisation reaction without indicator and evaporate the solution to dryness. OR - Insoluble metal carbonates and insoluble metal oxides can be added to acids, filtered and the filtrate can be evaporated to dryness.