[Part 2]- C5- Chemical changes ⚗️

Question 1

acid + carbonate———>

Answer 1

acid + [metal] carbonate———> salt + water + carbon dioxide

Question 2

acid + base——->

Answer 2

• acid + base——-> salt + water
• [This is also known as a neutralisation reaction.]

Question 3

acid + metal——>

Answer 3

acid + metal———> salt + hydrogen [gas]

Question 4

acid + alkali——>

Answer 4

acid + alkali———> salt + water

Question 5

What type of salt is produced, when hydrochloric acid reacts with metal ?

Answer 5

• hydrochloric acid, produces salts that end in the word -chloride

Question 6

What type of salt is produced, when sulfuric acid reacts with a metal ?

Answer 6

• hydrochloric acid, produces salts that end in the word -sulfate

Question 7

How does magnesium react with hydrochloric acid ?

Hint: why ?

Answer 7

• hydrochloric acid + magnesium—-> magnesium chloride + hydrogen
• magnesium reacts rapidly with acids, because magnesium is more reactive than hydrogen
• therefore it can easily displace hydrogen from acids.

Question 8

What is the equation for how magnesium reacts with sulfuric acid ?

Answer 8

• sulfuric acid + magnesium——> magnesium sulfate + hydrogen.

Question 9

How does zinc react with hydrochloric acid ?

Answer 9

• hydrochloric acid + zinc—-> zinc chloride + hydrogen.
• zinc reacts rapidly with acids since, is more reactive than hydrogen- therefore it can easily displace hydrogen from acids.

Question 10

What is the equation for the reaction of zinc and hydrochloric acid?

Answer 10

• zinc + hydrochloric acid——> zinc sulfate + hydrogen.

Question 11

How does iron react with hydrochloric acid ?

Answer 11

• hydrochloric acid + iron—> iron chloride + hydrogen.
• iron reacts slowly with acids.
• This is because although iron is more reactive than hydrogen, it’s only slightly more reactive= therefore the reaction will be slower.

Question 12

What is the equation for the reaction bewteen sulfuric acid and hydrogen ?

Hint: iron

Answer 12

• sulfuric acid + iron ——> iron sulfate + hydrogen.

Question 13

What is the rate of reaction with dilute acids ?

Hint: zinc

Answer 13

• magnesium- has a very rapid reaction and easily forms Mg2+
• zinc- has a quite rapid reaction and quite easily forms Zn2+
• ; iron- has a slow reaction, and less easily forms the positive ion Fe2+

Question 14

What happens when we react an acid, with a base or alkali ?

Hint: what are the products ?

Answer 14

• when we react an acid with a base or alkali, we make a salt and water.

Question 15

What do salts contain ? 🧂

Hint: ion

Answer 15

• salts contain a positive ion- this comes from the base or alkali.
• salts also contain a negative ion- this comes from the acid.

Question 16

What does sulfuric acid produce ?

Answer 16

• sulfuric acid produces sulfates

Question 17

What does hydrochloric acid produce ?

Answer 17

• nitric acid produces nitrates

Question 18

What happens when acids react with a metal carbonate ?

Answer 18

• when acids acids react with a metal carbonate, they make: a salt, a water and carbon dioxide.

Question 19

What is a strong acid ?

Answer 19

• a strong acid completely dissociates/ionises in aqueous solutions

Question 20

What are some examples of strong and weak acids

Answer 20

• strong acids:
• sulfuric acid
• nitric acid
• and hydrochloric acid
• weak acids:
• ethanoic acid
• citric acid
• carbonic acid

Question 21

What is a weak acid ?

Answer 21

• weak acids partially dissociates/ionises in aqueous solutions.
• a weak acid can be identified by this reversible reaction symbol: ⇌

Question 22

What the difference 🆚 a strong and weak acid ?

Answer 22

• a strong acid completely dissociates/ionises in aqueous solutions; - weak acids partially dissociates/ionises in aqueous solutions.

Question 23

How can the pH scale give us an idea of the concentration, of hydrogen ions [H+]?

Hint: strong

Answer 23

• strong acids have a lower pH, than weak acids, for a given concentration.
• this is because they fully dissociate/ionise, producing a greater concentration of hydrogen ions, than weak acids.

Question 24

What happens to the concentration of hydrogen ions, if the pH scale decreases by one unit ?

Answer 24

• if the pH scale decreases by one unit, the concentration of hydrogen ions increases by ten times. [by a factor of 1.0- known as one order of magnitude]
• and if the concentration of hydrogen ions decreases by a factor of 10, the pH increases by a factor of 1.0

Question 25

What does the concentration of an acid tell you ?

Answer 25

• the concentration of an acid tells you the amount of acid molecules, in a given volume of solution.
• a dilute acid has fewer acid molecules in a given volume
• compared to a concentrated acid, even if the strength of the acid is the same.