Chemical Change

Question 1

How do you measure the ph of a solution and what’s a oh probe

Answer 1

Universal indicator contains a dye that changes colour dependent if ph
Ph probe is attached to oh meter that measures ph electronically ,give numerical value ,more accurate than universal indicator

Question 2

Properties of acids and bases reactions

Answer 2

Acids form a substance a aqueous solution with a ph of less than 7, the acids form H+ions in water
Alkali is base dissolves in water to form solution with ph more then 7,the alkalis fork OH- ions in water

Question 3

What do acids form in water and what does it look like

Answer 3

The form protons,the protons are just H+ ions

Question 4

What happens to strong acids in reactions

Answer 4

Strong acids ionise completely in water
All acid particles dissociate to release H+ ions

Question 5

What happens to weak acids in reactions

Answer 5

Do not fully ionise, only small proportion of acid particles dissociate to release H+ ions
the ioniseation of weak acid is a reversible reaction which sets up an equilibrium between undissociated and dissociated acid

Question 6

Properties of the ph measure and calculations

Answer 6

Ph is measure of concentration of H+ ions in solution
Factor of H+ ion concentration changed by=10^-x
X being the difference in ph

Question 7

What do metal oxides and metal hydroxides react with to from

Answer 7

Acids in seprarate reactions to from both salt and water

Question 8

What do metal carbonates react with and form

Answer 8

Acids to form water, carbon and salt

Question 9

Describe the soluable salt practical

Answer 9

1.pick right acid,plus Insoluable base,eg insoluable hydroxide or carbonate
2.gently warm dilute acid with Bunsen burner,then turn off
3.add insoluable base to acid abit at time till no more reacts,you’ll know when acid is neutralised due to solid sinking to bottom of flask
4.filter out excess solid to get salt solution
5.heat solution using water bath to evap water then stop heating and leave to cool.salt crystals should form,which can be filtered out and dried

Question 10

Properties of the reactivity series

Answer 10

For metals it’s determined how easily they loose electrons -forming positive ions

Question 11

Why are carbon and hydrogen in the reactivty series

Answer 11

•metals that are less reactive than carbon can be extracted from their ores by reduction with carbon -metal more reactive than carbon can’t be extracted this way
• metals more reactive then hydrogen will react with acids

Question 12

What does metals reacting with acids tell you about their reactivity

Answer 12

Speed of reaction indicated by rate at which bubbles of hydrogen are given off

Question 13

What metals react with water

Answer 13

Will react :potassium,sodium,lithium,calcium
Wont react:zinc, iron and copper

Question 14

Why do metals have to sepoursted from their oxides

Answer 14

Metals are found in east as compounds and have to be extracted before used
Common metals found in the ground react with oxygen to form oxides
Process is called oxidisation
A reaction that sepourates metal from its oxide is a reduction reaction

Question 15

How does the restructure series determine whether it can be reacted by a reduction with carbon

Answer 15

Metals higher than carbon have be extracted using electrolysis,expensive
Metals below carbon can be extracted using reduction of carbon

Question 16

2 definition of oxidiseation reaction and reduction reaction

Answer 16

A loss of electrons is called oxidiseation
A gain of electrons is called reduction

Question 17

What does it mean by metal displacement reactions are redox reactions and what’s the rule

Answer 17

If you put reactive metal into a solution of dissolved metal compound,the reactive metal will displace the less reactive metal in the compound
This is a displacement reaction
A MORE REACTIVE METAL WILL ALWSYS DISPLACE A LESS REACTIVE METAL IN A COMPOUND