3b- Titrations, Energy and Chemical Tests

Question 1

What pH are acids on the pH scale? Why?

Answer 1

1

Lots of H+ (hydrogen) ions

Question 2

What pH are alkali on the pH scale? Why?

Answer 2

14

Lots of OH- (hydroxide) ions

Question 3

What are the neutralisation reactions?

Answer 3

acid + alkali → salt + water
acid + metal oxide → salt + water
acid + metal hydroxide → salt + water

Question 4

What is the reaction when testing for carbonates?

Answer 4

acid + carbonate → salt + water + carbon dioxide (fizzing)

Question 5

What is the reaction for reactive metals?

Answer 5

acid + metal → salt + hydrogen

Question 6

What is titration?

Answer 6

A way to measure volumes precisely

Question 7

What does titration find out?

Answer 7

Finds out an unknown concentration by using a known concentration

Question 8

What are the steps of titration?

Answer 8

• pipette measures an accurate volume of the solution and emptied in a conical flask
• indicator added to flask
• another chemical added into burette (with known concentration)
• solution from burette gradually added with swirling to mix indicator
• colour change shows the end point
• volume of solution added from burette is noted and used to calculate concentration

Question 9

What is reduction?

Answer 9

Gaining electrons

Question 10

What is oxidisation?

Answer 10

Losing electrons

Question 11

Electrolysis of Brine-

What gas is produced at the positive electrode?

Answer 11

Chlorine gas

Question 12

Electrolysis of Brine-

What gas is produced at the negative electrode?

Answer 12

Hydrogen gas

Question 13

Electrolysis of Brine-

What solution is formed?

Answer 13

Sodium hydroxide

Question 14

Electrolysis of Brine-

What is attracted to the cathode?

Answer 14

Hydrogen (H+) is attracted to the cathode (not sodium)

Greater force of attraction- not as many shells shielding the nucleus

Question 15

What is the test for oxygen?

Answer 15

Relight a glowing splint

Question 16

What is the test for hydrogen?

Answer 16

It makes a popping noise when lit

Question 17

What is the mnemonic for anode and cathode?

Answer 17

PANIC

Positive Anode Negative Is Cathode

Question 18

What is the relative atomic mass equation?

Answer 18

(mass of element needed ÷ total mass of elements) x weight or tonnes needed

Question 19

What is the formula for moles, mass, and atomic or formula mass?

Answer 19

mass = moles x atomic or formula mass

Question 20

What colour do the flames turn with these metal ions?
Lithium
Sodium
Potassium
Calcium
Barium

Answer 20

Lithium- crimson
Sodium- yellow
Potassium- lilac
Calcium- red
Barium- green

Question 21

What is the volume measured in and what is the conversion?

Answer 21

dm3

cm2 ÷ 1000 = dm3

Question 22

What is the formula for moles, volume and concentration

Answer 22

moles = volume (dm3) x concentration (mol.dm-3)

Question 23

What are the steps for titration calculations?

Answer 23

1) Work out chemical equation (acid + alkali → salt + water) and balance
2) Find ratio
3) Write table for concentration and volume of the chemicals
4) Use known chemical for vol x conc to find out moles
5) Put moles into ratio for the other chemical (if needed)
6) Use moles ÷ vol = concentration