Chemistry

Question 1

what is a chemical reaction?

Answer 1

a chemical reaction is a process that involves rearrangement of the molecule or ionic structure of a substance.

Question 2

what is an element?

Answer 2

a substance made from only one type of atom that cannot be broken down into a simpler substance.

Question 3

what is a mixture?

Answer 3

a substance that is physically combined.

Question 4

what is a compound?

Answer 4

a substance that is chemically combined by different elements.

Question 5

what is the word equation for photosynthesis?

Answer 5

carbon dioxide + water + light -> glucose and oxygen

Question 6

what is the chemical formula for carbon dioxide?

Answer 6

CO2

Question 7

what is the common name for H2O

Answer 7

water

Question 8

what is a reactant in a chemical reaction?

Answer 8

the two or more materials reacting together in a reaction.

Question 9

what is a product in a chemical reaction?

Answer 9

the resulting substances of a chemical reaction

Question 10

what is a chemical change?

Answer 10

the splitting and forming of new chemical bonds, giving new substances.

Question 11

what are some signs of a chemical reaction?

Answer 11

• change of colour
• odour
• change in temperature
• production of gas
• new substances formed
• bubbles
• combustion
• production of light

Question 12

what is a combustion chemical reaction?

Answer 12

a chemical reaction that includes burning.

Question 13

what reactant reacts with oxygen to form oxide compounds in a combustion reaction?

Answer 13

a fuel chemical.

Question 14

are combustion reactions exothermic or endothermic?

Answer 14

they release energy therefore are exothermic.

Question 15

what is a complete combustion in a chemical reaction?

Answer 15

all carbon dioxide atoms are completely oxidised.

Question 16

what is an incomplete combustion in chemical reactions?

Answer 16

not all carbon dioxide atoms are oxidised.

Question 17

what are the 3 common acids used in reactions?

Answer 17

• hydrochloric acid (HCL)
• sulphuric acid (H2SO4)
• nitric acid (HNO3)

Question 18

what are three types of bases?

Answer 18

• hydroxides, eg. sodium hydroxide (NaOH)
• oxides, eg. sodium oxide (Na2O)
• carbonates, eg. sodium carbonate (Na2CO3$

Question 19

what is a neutralisation reaction?

Answer 19

when an acid reacts with a base and salt and water is produced.

Question 20

what is the formula for a neutralisation reaction?

Answer 20

acid + base –> water + salt

Question 21

what is hydrochloric acid salt name?

Answer 21

chlorides

Question 22

what is sulphuric acid salt name?

Answer 22

sulphate

Question 23

what is nitric acid salt name?

Answer 23

nitrates.

Question 24

how do you name a salt?

Answer 24

the 1st word is the metal in the salt, 2nd word is the acid salt name.

Question 25

what is the neutralisation of hydrochloric acid and sodium hydroxide?

Answer 25

hydrochloric acid + sodium hydroxide --> sodium chloride + water

Question 26

what is the word formula for a acid and metal reaction?

Answer 26

acid + metal --> salt + hydrogen

Question 27

what is the word formula for an acid and carbonate reaction?

Answer 27

acid + carbonate --> salt + carbon dioxide + water.

Question 28

what is corrosion?

Answer 28

the process by which metals are broken down over a long period of time by reacting with substances within its environment.

Question 29

what is an example of corrosion?

Answer 29

iron reacting with oxygen and water creating rust.

Question 30

how does corrosion occur chemically?

Answer 30

ions losing electrons and the element is being reduced as it's gaining electrons.

Question 31

what is a precipitation chemical reaction?

Answer 31

when two salt solutions are combined and an insoluble salt is formed.

Question 32

what is the precipitation word equation for the reaction of silver nitrate and sodium chloride?

Answer 32

sodium chloride + silver nitrate --> sodium nitrate + silver chloride

Question 33

what is thermal decomposition?

Answer 33

when a chemical substance breaks down into at least two substances due to heat.

Question 34

what is electrical decomposition?

Answer 34

when a chemical substance breaks down due to a electrical current passing through it.

Question 35

is decomposition exothermic or endothermic?

Answer 35

requires energy therefore is endothermic.

Question 36

how can you test for the presence or carbon dioxide?

Answer 36

co2 reacts with like water, making the substance cloudy.

Question 37

how to test for hydrogen in the lab?

Answer 37

by igniting a flame, hydrogen makes a 'popping' noise.

Question 38

how to test for oxygen in the lab?

Answer 38

can cause splinters of wood to burst into flames.

Question 39

what is respiration?

Answer 39

chemical process by which organic compounds release energy.