EXAM QUESTIONS

Question 1

Describe what happens when a lithium atom reacts with a chlorine atom-4marks

Answer 1

Lithium is a metal and donates its valence electron and becomes a li ^+1 ion. The chlorine atom gains one electron in its outermost shell to form a chloride ion with charge ^ 1-. The oppositely charged atoms attract to form an ionic compound with ionic formula NaCl..,

Question 2

What is the formula of sodium nitride?

Answer 2

Na3N

Question 3

What flame test for testing a metal alkali produces Red flame?

Answer 3

Lithium

Question 4

What flame test for testing a metal alkali produces Intense Yellow/Orange Flame?

Answer 4

Sodium

Question 5

What flame test for testing a metal alkali produces Purple (Lilac/Violet) flame?

Answer 5

Potassium

Question 6

What flame test for testing a metal alkali produces Brick Red flame?

Answer 6

Calcium

Question 8

Covalent Bond Properties.

Question 9

Explain Why Graphite is very soft?

Answer 9

Because the carbon is arranged in layers with weak dispersion forces between the layers, this allows the layers to slide over one another.

Question 10

Explain Why Diamond is very Hard?

Answer 10

Because each carbon atom has 4 covelant bonds and thus they are very hard to break.

Question 11

Explain How Graphite conducts electricity.

Answer 11

Because of the delocalized valiance, electrons that are free to move between the layers and carry charge.

Question 12

State the force that exists between (HCI) Atom.

Answer 12

Dipole-Dipole Force.

Question 14

Explain why this allow is harder than pure metal Y ?

Answer 14

Because in pure metal the cations are of the same size , but in an alloy cations are of different sizes , and thus this stops cations from sliding over one another.

Question 15

Sate, what is meant by the term empirical formula?

Answer 15

Simplest whole number ratio formula.

Question 16

Calculate the percentage of S In HS.

Answer 16

97.0%

Question 17

Describe and explain how crude oil is separated into its fractions.

Answer 17

Heat oil.
Substances with high boiling points condense at the bottom and Substances with Low boiling points condense at the top of the fractionating column. Crude oil is evaporated. Its vapours condense at different. Temperatures. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms and a similar range of boiling of boiling points.

Question 18

Define the term electrolysis.

Answer 18

Electrolysis is the breakdown of ionic compounds, molten or aqueous/dissolved in solution, by the passage of electricity.

Question 19

Which bonds break when propane transitions from a liquid to a gas in the column?

Answer 19

Weak intermolecular forces/dispersion forces.

Question 20

Why do longer hydrocarbon chains have a higher viscosity?

Answer 20

Because smaller molecules have shorter chains and are less likely to get entangled, however, molecules that have larger chains are more likely to get entangled.

Question 21

Define viscosity?

Answer 21

Viscosity is a measure of a fluid’s resistance to flow.

Question 22

define the term fractional distillation

Answer 22

Fractional distillation separates a mixture into a number of different parts, called fractions. A tall fractionating column is fitted above the mixture. The column is hot at the bottom and cold at the top.

Question 23

Why can alkenes undergo addition reaction but alkanes cant?

Answer 23

Alkenes are unsaturated hydrocarbons and con undergo addition reactions, where as alkanes are saturated hydrocarbons and thus are not able to undergo addition reactions.

Question 24

Sodium sulfide? formula

Answer 24

na2s

Question 25

Sodium sulphate? formula

Answer 25

na2SO4

Question 26

How are metals able to conduct electricity?

Answer 26

Because of the delocalised valiance, electrons can move through the structure and carry charge.

Question 27

Why are metals malleable?

Answer 27

Metals can be bent and shaped as when metals are bent, hammered or pressed, layers of ions slip over one another.

Question 28

How are metals able to conduct heat?

Answer 28

Because they have delocalised valiance electrons that can move faster and transfer thermal energy quickly and easily.

Question 29

Why do metals have a high melting and boiling point?

Answer 29

Because the electrostatic forces of attraction between cations and delocalised electrons are strong and it requires a lot of energy to break them.

Question 30

Define the term alloy?

Answer 30

An alloy is a mixture of two or more elements, one of which is a metal.

Question 32

What is titration used for?

Answer 32

To find the concentration of a solution.

Question 33

Define the term, Haber process

Answer 33

The Haber process is the name given to the industrial production of ammonia. Nitrogen and hydrogen are reacted together using an iron catalyst to produce ammonia.

Question 34

Define the term electroplating?

Answer 34

Electroplating is a technique where a thin layer of a desired piece of metal is used to plate or coat another object.

Question 35

Why do we electroplate objects?

Answer 35

Helps us protect against rust. Improve apperance/make them look shiney. It is cheaper to plate than to make it out of a particular metal.

Question 36

Titration

Answer 36

Fill up a burette with acid. ... Use a pipette to add alkali to a conical flask. ... Add an indicator to the alkali dropwise ( 2-3 drops at a time). ... Get a retort stand and place the burette above and clonical flask below. place a white title underneath the cloncial flask Slowly add the acid into the alkali and swirl your flask slowy as adding akail ... Slow the adding of acid when the indicator changes colour. ... Stop adding acid when there is a permanent colour change. ... Record the titre. ... Repeat the titration until you have at least 3 concordant results

Question 37

Explain interms of electronic structure why flourine is he most reactive element in (Group7)?

Answer 37

Flourine is the smallest atom in (Group). Fluorine has the most significant attraction between the nucleus and outer shell. Therefore, fluorine can gain an electron into the outer shell more easily.