Reactions of Acids

Question 1

what does a reaction between a metal and an acid produce

Answer 1

metal + acid = salt + hydrogen

Question 2

what is the condition that has to be met in order for a metal + acid reaction to take place

Answer 2

• the metal has to be sufficiently reactive
• such as Mg being able to react
• but Cu not being able to

Question 3

what is the salt that is formed and what does this property imply about its state

Answer 3

• it is soluble

- so it is in an aqueous state when produced

Question 4

what would always be visually seen during this reaction

Answer 4

bubbles of hydrogen gas escaping from the solution

Question 5

what would the equation for Mg and 2HCl reacting together

Answer 5

Mg + 2HCl = MgCl2 + H2

Question 6

why can these reactions be called neutralisation reactions

Answer 6

• because the H+ ions are removed from the water

- apart from the very small numbers present in water

Question 7

what type of reactions are these, also, and why

Answer 7

• redox reactions
• because there is a transfer of electrons from the Mg to the H+ ions
• or in general terms, from the metal to the H+ ions

Question 8

what is the general equation for the reaction between a metal oxide and an acid

Answer 8

metal oxide + acid = salt + water

Question 9

what is the general equation for the reaction between a metal hydroxide and an acid

Answer 9

metal hydroxide + acid = salt + water

Question 10

why does the reactivity of the metal not matter in these reactions

Answer 10

• because the metal in the reactant is present as metal ions, not atoms
• this is due to it being in a solution, making it aqueous

Question 11

what would you visually observe from these reactions

Answer 11

usually just the formation of the product / solution

Question 12

what would be the equation for the reaction between CuO and H2SO4

Answer 12

CuO + H2SO4 = CuSO4 + H2O

Question 13

what would be the equation for the reaction between Zn(OH)2 and H2SO4

Answer 13

Zn(OH)2 + H2SO4 = ZnSO4 + 2H2O

Question 14

what type of reactions are these and why

Answer 14

• neutralisation reactions
• because the H+ ions react with the O2- ions or the OH- ions
• producing water

Question 15

why arent these reactions redox reactions

Answer 15

because there isnt a change in the oxidation number of any of the species

Question 16

what is the general equation for the reactions between acids and alkalis

Answer 16

metal hydroxide + acid = salt + water

Question 17

if there are no visible changes during these reactions, what could you do to see whether a reaction is occurring

Answer 17

• put a thermometer in the solution

- a rise in temperature should be detected

Question 18

what are the three typical equations for the reaction between NaOH and H3PO4, phosphoric acid

Answer 18

• NaOH + H3PO4 = NaH2PO4 + H2O
• 2NaOH + H3PO4 = NaHPO4 + 2H2O
• 3NaOH + H3PO4 = NaPO4 + 3H2O

Question 19

what does the type of reaction between sodium hydroxide and phosphoric acid that occurs depend on

Answer 19

the relative amounts of them used

Question 20

what is the ionic equation for this reaction

Answer 20

H+ + OH- = H20

Question 21

what does that ionic equation imply about the reaction

Answer 21

• it is a neutralisation reaction
• as the H+ ions and OH- ions react and neutralise each other
• but it is not a redox reaction

Question 22

what is the general equation for the reaction between acids and metal carbonates

Answer 22

metal carbonate + acid = salt + water + carbon dioxide

Question 23

what are the two things that are practically formed

Answer 23

• bubbles of carbon dioxide gas

- and a solution if the salt is soluble

Question 24

what is the equation for the reaction between LiCO3 and 2HCl

Answer 24

LiCO3 + 2HCl = LiCl2 + CO2 + H2O

Question 25

what types reactions are these

Answer 25

• neutralisation reactions
• because the H+ ions react with the CO2- ions
• to form CO2 and H2O
• but they are not redox reactions as there is no change in the oxidation number of any species

Question 26

what are hydrogencarbonates

Answer 26

compounds containing the hydrogencarbonate ion HCO3-

Question 27

what general equation is the reaction between H-carbonates and acids identical to in terms of products

Answer 27

the equation for a metal carbonate + acid

Question 28

what is the most common H-carbonate

Answer 28

• sodium hydrogencarbonate
• NaHCO3
• also known as baking soda or bicarbonate of soda

Question 29

why is baking soda used in baking and why does it cause the effect it does

Answer 29

• because it causes the food to rise and become light

- this is due to the formation of bubbles of carbon dioxide in the bake mixture

Question 30

what does the baking soda react with in the food generally

Answer 30

citric acid

Question 31

what is the general equation for the reaction between sodium hydrogencarbonate and citric acid

Answer 31

sodium hydrogencarbonate + citric acid = sodium citrate + water + carbon dioxide

Question 32

what is the test for the presence of carbonate or hydrogencarbonate ions in a solid or solution

Answer 32

• add an aqueous acid
• and test the gas given off with limewater
• if it turns cloudy it is CO2
• meaning the ions are present