Acids and Alkalis

Question 1

What does metal + acid form?

Answer 1

Salt + hydrogen

Question 2

What does metal oxide + acid form?

Answer 2

Salt + water

Question 3

What does metal hydroxide (alkali) + acid form?

Answer 3

Salt + water

Question 4

What does metal carbonate + acid form?

Answer 4

Salt + water + carbon dioxide

Question 5

What does ammonia + acid form?

Answer 5

Ammonia salt

Question 6

What is an acid?

Answer 6

An acid is a substance that has a pH lower than 7 on the pH. And releases H+ ions.

Question 7

What is the difference between strong and weak acids?

Answer 7

A strong acid fully ionises in solutions (the ions fully separate). In a weak acid, the ions only partially separate, they don’t fully ionise).

Question 8

What is an alkali?

Answer 8

An alkali releases OH- ions in solutions and has a pH higher than 7.

Question 9

What is the difference between strong and weak alkali?

Answer 9

A strong alkali is completely ionised and weak are partly ionised.

Question 10

What are properties of acids?

Answer 10

☆They have a sour test taste when edible like lemon and vinegar
☆They are corrosive
☆When they are added to water they form positively charged hydrogen ions (H+)
☆ Presence of positively charged hydrogen ions is what makes the solution acidic

Question 11

What is the formula for hydrochloric acid?

Answer 11

HCl

Question 12

What is the formula for nitric acid?

Answer 12

HNO(3)

Question 13

What is the formula for sulphuric acid?

Answer 13

H(2)SO(4)

Question 14

What are the properties of alkalis?

Answer 14

☆They are soluble (able to dissolve) in water
☆They feel soapy to the touch and taste bitter
☆They are usually oxides or hydroxides of metals
☆The presence of the negatively charged hydroxide ions is what makes aqueous solutions alkali.

Question 15

What is the formula of Calcium hydroxide?

Answer 15

Ca(OH)2

Question 16

What is the formula of sodium hydroxide?

Answer 16

NaOH

Question 17

What colour does litmus solution turn in acid?

Answer 17

Red

Question 18

What colour does litmus solution turn in alkali?

Answer 18

Blue

Question 19

What colour does methyl orange turn in acid?

Answer 19

Red

Question 20

What colour does methyl orange turn in alkali?

Answer 20

Yellow

Question 21

What does universal indicator turn in acid?

Answer 21

Red

Question 22

What does universal indicator turn in alkali?

Answer 22

Purple

Question 23

What does universal indicator turn in neutral substance?

Answer 23

Green

Question 24

What is an indicator?

Answer 24

It determines if a substance is a strong/weak acid or alkali by changing colour. It can only give an approximate measure and is useful when estimating the pH of an unknown solution.

Question 25

What is a neutralisation reaction?

Answer 25

Occurs when an acid reacts with an alkali. When these substances react together, the H+ ions react with OH- ions to produce water.

Question 26

What is proton transfer?

Answer 26

☆Acids are proton donors as they ionise in solutions producing protons, which are H+ ions
☆Bases (alkalis) are proton accepters as they accept the protons which are donated by the acid

Question 27

Acids reaction with metals -

Answer 27

☆Only metals above hydrogen in the reactivity series will react with dilute acids. The more reactive the metal the more vigorous the reaction will be. Potassium and Sodium will react explosively with acids.
Metal + acid — salt + hydrogen