Acids, Alkalis, And Salts

Question 1

How did people identify acids ?

Answer 1

From their taste and from their sour taste

Question 2

How did people identify alkalis ?

Answer 2

From their taste and from their soapy feel

Question 3

What are indicators ?

Answer 3

Special dyes that change color in acids and alkalis

Question 4

What is litmus ?

Answer 4

Indicator that is red in acid and blue in alkali

Question 5

What is universal indicator ?

Answer 5

Tells us how strongly acidic or alkaline a substance is

Question 6

When does methyl orange turn red ?

Answer 6

When in an acidic solution

Question 7

When does methyl orange turn yellow ?

Answer 7

When it’s either neutral or alkaline

Question 8

What are the colors of phenolphthalein ?

Answer 8

Colorless as neutral and acid, but pink when alkaline

Question 9

What happens if the acid is stronger ?

Answer 9

The more dangerous and corrosive it is a

Question 10

What are the main points in the Ph scale ?

Answer 10

Ph 1 is a strong acid
Ph 6 is a weak acid
Ph 7 is neutral
Ph 8 is a weak alkali
Ph 14 is a sting alkali

Question 11

What is neutralisation ?

Answer 11

A réaction where an acid reacts with an alkali to for a neutral solution

Question 12

State examples of a neutralisation reaction ?

Answer 12

Antacids, farmers neutralize soils

Question 13

Universal indicator and the ph scale :

Question 14

How does hydrochloric acid not burn through the stomach ?

Answer 14

The stomach has a protective layer

Question 15

Acids :

Answer 15

Acids form acidic solutions in water

Acids are sources of hydrogen ions, H+
Ex: hydrochloric acid produces hydrogen ions
HCI(aq)—> H+(aq) + Cl-(aq)

Question 16

What are acids ?

Answer 16

Substances that :
Turn litmus red
Have a ph below 7 and turn universal indicator yellow, orange or red
They contain hydrogen ions ( H+ )
Ex: hydrochloric acid is a strong acid but Ethanoic acid (vinegar) is a weak acid

Question 17

Alkalis :

Answer 17

They form alkaline solutions in water
Alkalis are sources of hydroxide ions ( OH- )
Ex: sodium hydroxide produces hydroxide ions:
NaOH(aq) —> Na+(aq) + OH-( aq )

Question 18

What are alkalis ?

Answer 18

Substances that :
Turn litmus blue
Have a ph above 7 and turn universal indicator blue or purple
Contain OH- ions
Ex:
sodium hydroxide is a strong alkali
Ammonia is a weak alkali

Question 19

What happens with atoms with incomplete outer electron shells ?

Answer 19

They are unstable

Question 20

How can atoms obtain a full outer electron shell and be stable ?

Answer 20

By gaining or losing electrons

Question 21

How do atoms become ions ?

Answer 21

Atoms with incomplete outer electron shells are unstable. By either gaining or losing electrons, atoms can obtain full outer electron shells and become stable.
When this happens, atoms have an unequal number of protons and electrons and so have an overall charge.

Question 22

What is neutralization?

Answer 22

When an acid and an alkali react in a neutralisation reaction the hydrogen ions react with the hydroxide ion to produce a neutral substance.

Question 23

What is the equation for neutralisation ?

Answer 23

Acid + Alkali→Water

Question 24

What happens when an acid and an alkali react in a neutralisation reaction ?

Answer 24

the hydrogen ions react with the hydroxide ion to produce a neutral substance.
Hydrogen ion (acid) = H+ Hydroxide ion (alkali) = OH-
H+ +OH-➔H2O

Question 25

What do all acids contain ?

Answer 25

H+ ions

Question 26

What do all alkalis contain?

Answer 26

OH- ions

Question 27

Explain the concentration of ions ?

Answer 27

The pH of a solution is a measure of its concentration of hydrogen ions:
• the higher the concentration of H+ ions in an acidic solution, the lower the pH
• the lower the concentration of H+ ions in an acidic solution, the higher the pH