Science Task 2

Question 1

Quick Note:
What are the products of each of the following?

1. Acid + Base
2. Acid + Metal
3. Acid + Metal Hydroxide
4. Acid + Carbonate

Answer 1

1. Acid + Base - Salt + Water
2. Acid + Metal - Salt + Hydrogen Gas
3. Acid + Metal Hydroxide - Salt + Water
4. Acid + Carbonate - Salt + Water + Carbon Dioxide

Question 2

What is the maximum number of electrons that can fit in the first three electron shells of an atom

Answer 2

2,8,8

Question 3

What is Ionic Bonding? And do they give or share electrons?

Answer 3

Bonding between non-metals and metals. They give electrons.

Question 4

What is covalent Bonding? And do they give or share electrons?

Answer 4

Bonding between two nonmetals. They share electrons.

Question 5

Outline how to name COVALENT compounds

Answer 5

1. Write the name of the element closest to the bottom left of the periodic table
2. -ide replaces the end of the second element
3. Where a molecule contains more than one atom of the same kind, the number of atoms is indicated by the prefixes. Prefixes are given to the first and second element, however, if the first element has one atom we do not say ‘mono’.

Question 6

List the prefixes from 1-10 used when naming covalent compounds

Answer 6

1 - Mono
2 - Di
3 - Tr
4 - Tetr/a
5 - Pent/a
6 - Hex/a
7 - Hept/a
8 - Oct/a
9 - Non/a
10 - Dec/a

Question 7

Outline how to name IONIC compounds

Answer 7

1. The metal is placed first
2. -Ide is added to the end of the non-metal

Question 8

What ions do Acids produce?

Answer 8

Hydrogen (H+)

Question 9

What are some uses of acids?

Answer 9

Drugs
Plastics
Fertilisers

Question 10

List some characteristics of Acids

Answer 10

Have a sour taste
Are corrosive
pH under 7
Turns universal indicator red/orange/yellow
The chemical formula of all acids contain a hydrogen atom

Question 11

What ions do Bases produce

Answer 11

produces hydroxide ions (OH⁻)

Question 12

What are some uses of bases

Answer 12

Indigestion Remedies
Cleaning Products
Soap making

Question 13

List some characteristics of bases

Answer 13

Have a bitter taste
Are slippery to touch
pH over 7
Turns universal indicator blue/purple

Question 14

Describe the pH scale as a way of measuring the acidity and basicity of substances

Answer 14

The pH scale is a scientific scale used to measure how acidic or basic a substance is. It ranges from 0 to 14, with 7 being neutral. A substance with a pH below 7 is acidic, while a substance with a pH above 7 is basic. To test the pH, indicators such as universal indicators or natural indicators like red cabbage juice are added to the substance. These indicators change colour depending on the pH level—acids typically turn the indicator red, orange, or yellow, bases turn it blue or purple, and neutral substances make the indicator green.

Question 15

Outline what an indicator is

Answer 15

An indicator is a substance used to show whether a solution is acidic, neutral, or basic by changing colour. Some such as universal indicator react with the solution to produce a visible colour change depending on the pH level. Others such as Blue and Red litmus paper either change red for acids or blue for bases and do not indicate the pH.

Question 16

What is the role of indicators

Answer 16

Determining whether substances are Acids, Bases or Neutrals.
They allow for easy identification and monitoring of reactions and changes
Visually demonstrating the presence or changes in acidity or alkalinity within a solution
Scientists can observe and measure chemical changes like neutralisation.
Many such as universal indicator show the pH of the substance

Question 17

What is a neutralisation reaction?

Answer 17

A neutralisation reaction occurs when an acid mixes with a base and the hydrogen ions (H+) from the acid combine with the hydroxide ions (OH-) from the base to form water (neutral) and salt. This substance is neutral with a pH of around 7 and is neither an Acid or Base.

Question 18

What is the format of a neutralisation reaction. ie. what are the reactants and products?

Answer 18

Acid + Base → Salt + Water

Note: The salt comes from the type of base followed by the type of acid.

Question 19

Are neutralisation reactions endothermic or exothermic

Answer 19

Exothermic

Question 20

Define a precipitate

Answer 20

A precipitate is an insoluble salt that forms when two clear (aqueous) solutions are mixed and a new solid appears. This solid does not dissolve in the solution.

Question 21

What is the formatting of a precipitation reaction?

Answer 21

Soluble salt A (aq) + Soluble salt B (aq) → Insoluble salt (precipitate, s) + Soluble salt C (aq)

Question 22

How do you write a word equation for a precipitate reaction?

Answer 22

Potassium Iodide + lead nitrate → lead iodide + Potassium nitrate

➡ The outside products are combined and the middle products are combined

Question 23

Describe one test used to determine the presence of HYDROGEN GAS

Answer 23

➡ The ‘Pop test’
Hydrogen gas is highly flammable. When a small amount of it is exposed to a flame, it combusts rapidly.
After a chemical reaction has occurred, take a lit match and hold it over the reaction vessel. If hydrogen was produced you should hear a squeaky pop sound and the flame will likely go out.

If this does not occur, no hydrogen gas was produced.

Question 24

Describe one test used to determine the presence of CARBON DIOXIDE

Answer 24

➡ Turning limewater milky
Carbon dioxide reacts with calcium hydroxide (limewater) to form calcium carbonate, which is insoluble and turns the liquid cloudy.
After completing the experiment (where the gas is produced), attach a delivery tube to the reaction vessel. The tube should be connected so the gas can travel through it.
Place the other end of the delivery tube into a beaker with a small amount of lime water (calcium hydroxide solution).
As the gas bubbles through the limewater, observe the reaction.

If the limewater turns milky or cloudy, it means carbon dioxide (CO₂) is present. The cloudiness occurs because CO₂ reacts with calcium hydroxide to form calcium carbonate, which is insoluble.

Question 25

Outline how a word equation is written when acids and metals react

Answer 25

Write the name of the acid (e.g. hydrochloric acid, sulfuric acid). + Write the name of the metal (e.g. magnesium, zinc). → Salt: The salt’s name is based on the metal then type of acid Hydrogen gas is always produced. Therefore: Acid + Metal → Metal Salt + Hydrogen

Question 26

Outline how a word equation is written when acids and carbonates react

Answer 26

Write the name of the acid (e.g. hydrochloric acid). + Write the name of the carbonate (e.g. calcium carbonate). → Salt: The type of carbonate combined with the acids is the salt produced Water + Carbon Dioxide Therefore: Acid + Carbonate → Carbonate Name Salt + Water + Carbon Dioxide

Question 27

Outline how a word equation is written when acids and metal hydroxides

Answer 27

Acid + Metal hydroxide → Salt + Water The salt is found by taking the name of the Metal and combining it with the acid salt type

Question 28

List the 4 factors that affect the rate of reaction

Answer 28

Temperature Concentration Surface Area Catalyst

Question 29

Describe how temperature affects rate of reaction

Answer 29

Higher temperature = faster reaction Heating particles increases their kinetic energy, causing them to move faster. This leads to more frequent collisions, each with a higher chance of being successful due to the increased energy. If you want to slow down a reaction you can cool it down. This is why food such as bread is often placed in the fridge - stops the decomposition reaction.

Question 30

Describe how concentration affects rate of reaction

Answer 30

Higher concentration = faster reaction The concentration of a substance is the measure of how there is of a substance in a certain amount of solution. The higher concentration = The more particles in the same = more collisions = faster reaction rate

Question 31

Describe how surface area affects rate of reaction

Answer 31

More surface area (e.g. powder vs. lump) = faster reaction More area for particles to collide with. Increasing the surface area increases the number of particles exposed for collision, which leads to more frequent collisions and a higher chance of a reaction occurring.

Question 32

Describe how catalyst affects rate of reaction

Answer 32

Catalysts speed up a reaction without being used up in the process. They work by lowering the activation energy, providing an alternative pathway for bonds to break and reform. With lower activation energy, more particles have enough energy to react, increasing the rate of reaction. They also providing a site for reactants to attach to specific parts of the catalyst which allows the reactants to collide at the right orientation

Question 33

Outline the collision theory

Answer 33

According to the collision theory, particles must collide with enough kinetic energy—called activation energy—and the correct orientation for a reaction to occur. A successful collision breaks existing bonds and forms new ones, triggering a chemical reaction. Reactions with low activation energy happen more easily than those with higher activation energy.

Question 34

How can the rate of reaction be measured?

Answer 34

Amount of product formed/time

Question 35

Define activation energy

Answer 35

Activation energy is the minimum amount of energy that particles need to collide and start a chemical reaction.

Question 36

What is a salt

Answer 36

A salt is an ionic compound that contains both a negative and positive ion.

Question 37

Outline Endothermic Reactions

Answer 37

Cold outside, temp inside increases

Question 38

Outline Exothermic Reactions

Answer 38

Warm outside, temp inside decreases