Top of the Bench - reactions

Question 1

what is a precipitation reaction?

Answer 1

when a solid is produced from two solutions

Question 2

what technique would you use to recover the precipitate?

Answer 2

Filtration.

Question 3

what is a neutralisation reaction

Answer 3

when an acids pH is brought towards 7 by reaction with a base (metal oxide, hydroxide or carbonate)

Question 4

what are the products of a neutralisation reaction

Answer 4

-A salt and water
-If the base is a carbonate, C02 is also produced.

Question 5

How do you extract a soluble salt after the reaction.

Answer 5

-Excess insoluble base is filtered out solution (excess neutraliser added to acid to ensure complete neutralisation).
-gently heat solution and allow liquid to EVAPORATE extract the dissolved salt.

Question 6

what is a combustion reaction?

Answer 6

-a reaction when a substance releases energy when reacting with oxygen.
-all hydrocarbons are fuels and can combust - they produce C02 and water

Question 7

what is an exothermic reaction?

Answer 7

-A chemical reaction which releases energy and causes temperature rise

Question 8

what is an endothermic reaction

Answer 8

-A reaction that takes in energy and causes a temperature fall.

Question 9

what is an addition reaction

Answer 9

-when an element is added over a carbon to carbon double bond

Question 10

what is hydration

Answer 10

-type of addition reaction
-adding water
-alkene to alcohol
-opposite is dehydration

Question 11

what is hydrogenation

Answer 11

-type of addition reaction
-adding hydrogen over the double bond
-alkene to alkane

Question 12

what is halogenation

Answer 12

-type of addition reaction
-adding a halogen over double bond
-alkene to halogenalkane

Question 13

what is the product of the reaction of ethene with hydrogen

Answer 13

ethane (hydrogenation)

Question 14

what is the product of the reaction of propene and chlorine

Answer 14

1,2-dichloropropane (halogenation)

Question 15

what is the product of the reaction of but-1-ene and fluorine

Answer 15

1,2-difluorobutane (halogenation)

Question 16

what is the product of the reaction of but-2-ene and fluorine.

Answer 16

2,3-difluorobutane (halogenation)

Question 17

what is the product of the reaction of ethene and water

Answer 17

ethanol (hydration)

Question 18

what are flame tests

Answer 18

flame tests tell us the type of metal present due to the flame colour.

Question 19

what is polymerisation

Answer 19

polymerisation is an addition reaction of many monomers making a polymer

Question 20

what is a redox reaction

Answer 20

redox retractions involve an oxidation and a reduction reaction

Question 21

name two gases which can form acid rain

Answer 21

sulfur dioxide and carbon dioxide, can dissolve in rain water and produce acid.

Question 22

what can enzymes change glucose into

Answer 22

enzymes can change glucose into alcohol through the reaction of fermentation.

Question 23

word equation for respiration (aerobic)

Answer 23

Glucose + oxygen –> carbon dioxide + water

Question 24

what is the word equation of photosynthesis

Answer 24

carbon dioxide + water –> glucose + oxygen

Question 25

during electrolysis what reaction occurs at the negative electrode

Answer 25

reduction (of the metal of the ionic compound)

Question 26

during electrolysis what reaction occurs at the positive electrode

Answer 26

oxidation (of the non metal of the ionic compound)