Cauldron Chemistry

Question 1

What are the characteristics of a chemical reaction?

Answer 1

• colour change
• precipitate
• gas produced
• temperature change
• disappearance of a solid
• odour produced

Question 2

Define the term endothermic.

Answer 2

• chemical reaction
• absorbs energy in the form of heat.

Question 3

What is combustion?

Answer 3

• exothermic reaction
• between a fuel and oxygen gas releasing heat.

Question 4

Define the term exothermic.

Answer 4

• chemical reaction
• releases energy in the form of light or heat.

Question 5

What is cellular respiration?

Answer 5

• exothermic
• involves the reaction of glucose with oxygen.
• produces carbon-dioxide + water + energy

Question 6

What is a precipitation reaction?

Answer 6

• chemical reaction
• two solutions to produce a solid precipitate.

Question 7

What are the products of both complete and incomplete combustion?

Answer 7

Complete: carbon dioxide + water

Incomplete: carbon + carbon monoxide + water

Question 8

What is a word equation for cellular respiration?

Answer 8

glucose + oxygen → carbon dioxide + water (+ energy)

Question 9

Explain the Conservation of Mass.

Answer 9

• New substances are formed during a chemcial reaction
• the atoms are re-arranged, NOT created or destroyed

Question 10

What is an atom?

Answer 10

The smallest unit of matter that has mass.

Question 11

Describe the formation of an ion.

Answer 11

The loss or gain of an electron to obtain a full outer shell.

Question 12

What is an ion?

Answer 12

• An ion is a charged atom or molecule.
• the number of electrons do not equal the number of protons in the atom or molecule.

Question 13

What is an ionic bond?

Answer 13

The attraction between oppositley charged metal and non-metal ions.

Question 14

What is a covalent bond?

Answer 14

The sharing of one pair of electrons between two non-metal atoms

Question 15

True or False? Compounds can be decomposed by chemical means.

Answer 15

True.

Question 16

What is decomposition?

Answer 16

• chemical reaction
• requires energy input to break down a reactant into two or more simpler substances.

Question 17

What are the characteristics of acids?

Answer 17

• sour taste
• feels gritty
• corrosive (rust metals)
• pH of less than 7
• contain hydrogen
• neutralises bases
• turns blue litmus paper red

Question 18

What are the characteristics of bases?

Answer 18

• bitter taste
• slippery feel
• pH of more than 7
• turns red litmus paper blue
• blue/purple universal indicator

Question 19

In solutions, what ions do acids and bases have?

Answer 19

Acids: hydrogen ions (H)

Bases: hydroxide ions (OH)

Question 20

What chemical reaction is digestion in the stomach?

Answer 20

• releases energy (exothermic).
• chemical decomposition of proteins into smaller substances (amino acids)

Question 21

What is an enzyme?

Answer 21

• a type of catalyst
• found in the body to help assist digestion
• an example of an enzyme is pepsin.

Question 22

What is corrosion?

Answer 22

• chemical reaction
• usually between a metal an acid (or oxygen gas)

Question 23

Give an example of an acid + metal word equation.

Answer 23

magnesium + hydrochloric acid → magnesium chloride + hydrogen

Question 24

What is a catalyst?

Answer 24

A substance that increases the rate of reaction but is not consumed by the reaction.

Question 25

Describe the test for carbon-dioxide.

Answer 25

* **lime water** reacts with carbon dioxide to produce a **precipitate of calcium carbonate.**

Question 26

Describe the test for hydrogen gas.

Answer 26

* bring a **lit match** **next to the gas** and it should **pop**. * The name of the salt changed depending on the name of the acid and metal.

Question 27

Describe the test for oxygen.

Answer 27

* Oxygen is the only gas that will support burning. * It is the only gas that will **relight a glowing splint.**

Question 28

What is neutralisation?

Answer 28

* chemical reaction * involves an **acid** + **base** = **salt and water**.

Question 29

Give an example of a neutralisation reaction word equation.

Answer 29

**sulfuric acid + potassium hydroxide → potassium sulfate + water**

Question 30

Give examples of acids.

Answer 30

* hydrochloric acid * **HCl** * nitric acid * **HNO₃** * sulfuric acid * **H₂SO₄**

Question 31

Give examples of bases.

Answer 31

* Sodium hydroxide * **NaOH** * Potassium hydroxide * **KOH** * Calcium hydroxide * **CaOH**

Question 32

How to classify binary compounds as ionic or covalent:

Answer 32

* metal and a non-metal = ionic. * two non-metals = covalent.

Question 33

How are respiration and combustion similar reactions?

Answer 33

They are both: * Exothermic * Involve the reaction between a fuel or oxygen * Produce CO₂ + H₂O + energy