pH, Acids And Bases

Question 1

What happens to the solution as the ph value decreases?

Answer 1

The solution is becoming more acidic

Question 2

What happens to the solution as the ph value increases?

Answer 2

The solution becomes more alkaline

Question 3

Corrosive substances usually have what?

Answer 3

A very low or high ph

Question 4

Which substances conduct electricity?

Answer 4

Metals, ionic compounds, ionising covalent compounds, dissolved ionic compounds (aq) and liquid ionic compounds

Question 5

Which substances don’t conduct electricity?

Answer 5

Non-metals, covalent compounds and solid ionic compounds

Question 6

Why do acid solutions have a ph less than 7

Answer 6

Because they have a higher concentration of Hydrogen ions than hydroxide ions when compared to pure water

Question 7

Why do alkaline solutions have a ph greater than 7?

Answer 7

Because they contain a higher concentration of hydroxide ions than hydrogen ions when compared to pure water

Question 8

What do non-metal oxides produce?

Answer 8

Non-metal oxides which dissolve in water increases the concentration of hydrogen ions (compared to pure water) and therefore produce acidic solutions

Question 9

What do metal oxides produce?

Answer 9

Metal oxides which dissolve in water increase the hydroxide concentration (compared to pure water) and therefore produces alkali solutions

Question 10

Acid reacts with metals to form what?

Answer 10

Acids react with metals to form a salt and hydrogen gas

Question 11

Acid reacts with carbonates to form what?

Answer 11

Acids react with carbonates to form a salt, water and carbon dioxide gas

Question 12

What are the general equations for reactions of acids?

Answer 12

Metal + acid forms salt + hydrogen
Metal carbonate + acid forms salt + carbon dioxide + water
Metal oxide + acid forms salt + water
Metal hydroxide + acid forms salt + water

Question 13

Why does the ph of an acid move towards 7?

Answer 13

Because the hydrogen ion concentration is being reduced as they react to form water molecules

Question 14

Why does the ph of an alkali move towards 7?

Answer 14

Because the hydroxide ion concentration is being reduced as they react to from water molecules

Question 15

What is a base?

Answer 15

Compounds which neutralise acids to produce water

Question 16

What is a salt?

Answer 16

A salt is a compound formed when the metal ion from an alkali replaces the hydrogen ion of an acid

Question 17

A balanced ionic state equation can be expanded and written from a word equation by following what procedure?

Answer 17

B- write a Balanced equation
I- show the charges on Ionic compounds
S- introduce State symbols (s, aq, g, l)
E- Expand ionic formulae of solutions

Question 18

What do you calculate the number of moles?

Answer 18

Number of moles = concentration x volume

Question 19

What do you calculate the mass?

Answer 19

Mass=number of moles x mass of 1mole (gfm)

Question 20

What are the steps to calculating the mass if you are given the concentration and volume?

Answer 20

Step 1 = number of moles = concentration x volume

Step 2 = mass = number of moles x mass of 1 mole (gfm)

Question 21

How do you calculate the concentration if you are given the volume and mass?

Answer 21

Step 1 = Number of moles = mass divided by mass of 1 mole (gfm)
Step 2 = concentration = number of moles divided by volume

Question 22

What steps do you use to calculate the concentration of an acid using volume and concentration

Answer 22

Step 1= write a balanced equation
Step 2= calculate the number of moles of the standard solution
Step 3= use the mole relationship to the calculate the number of moles of the unknown
Step 4= calculate the concentration of the unknown using the equation concentration=number of moles divided by volume