Acids & Redox

Question 1

When an acid is added in water what ion is released into the solution?

Answer 1

H+

Question 2

Define acid

Answer 2

Proton donor

Question 3

Describe the dissociation of a strong acid.

Answer 3

Fully dissociates

Question 4

Define base

Answer 4

Proton acceptor

Question 5

What are alkalis?

Answer 5

Bases that can dissolve in water to form OH-

Question 6

What is formed when acid reacts with carbonate?

Answer 6

Salt, carbon dioxide and water

Question 7

What is a salt?

Answer 7

A compound that is formed when H+ is replaced by a metal ion

Question 8

What is formed when acids react with oxides?

Answer 8

Salt and water

Question 9

What is formed when acid reacts with alkali?

Answer 9

Salt and water

Question 10

What is formed when acids react with metals?

Answer 10

Salt and hydrogen

Question 11

Why are the products the same when both alkalis and oxides react with acid?

Answer 11

They’re both bases

Question 12

What does a dot formula indicate?

Answer 12

Water of crystalisation

Question 13

What is an oxidation number?

Answer 13

The number of electrons an atom uses to bond with any other atom

Question 14

What is the oxidation number of an uncombined element?

Answer 14

0

Question 15

What is the oxidation number of oxygen in a combined element such as H2O?

Answer 15

-2

Question 16

What is the oxidation number of oxygen in peroxides?

Answer 16

-1

Question 17

What is the oxidation number of combined hydrogen such as NH3?

Answer 17

+1

Question 18

What is the oxidation number of combined hydrogen such as NH3?

Answer 18

+1

Question 19

What is the oxidation number of combined hydrogen in metal hydrides?

Answer 19

-1

Question 20

What is the oxidation number of a simple ion?

Answer 20

Example Na+ = +1

Question 21

Define oxidation in terms of electrons and oxidation number.

Answer 21

Loss of electrons and an increase in oxidation number

Question 22

Define reduction in terms of electrons and oxidation numbers.

Answer 22

Gain of electrons and decrease in oxidation number

Question 23

What are the formula of 4 common acids?

Answer 23

hydrochloric acid -> HCl
sulphuric acid -> H2SO4
nitric acid -> HNO3
ethanoic acid -> CH3COOH

Question 24

What are the formulae of 3 common alkalis?

Answer 24

sodium hydroxide -> NaOH
potassium hydroxide -> KOH
ammonia -> NH3

Question 25

How do you prepare a standard solution in an acid-based titration?

Answer 25

1. Solid is weighed accurately 2. Solid dissolves in a beaker with distilled water, less than what is needed to fill flask 3. Solution is transferred to a volumetric flask (traces are rinsed with distilled water into the flask) 4. Flask filled to the graduation line by adding distilled water a drop at a time until the bottom of the meniscus lines up exactly at eye level (if over solution must be prepared again) 5. Flask slowly inverted many times to mix solution thoroughly (if not done titration results will be inconsistent)

Question 26

How do you prepare a titration?

Answer 26

1. Fill the burette with the standard solution 2. Use a pipette filler to transfer 25cm3 of HCL to the conical flask 3. Add 3 drops methyl orange 4. Record initial burette reading 5. Titrate the contents of the conical flask by adding the solution from the burette into the conical flask until a colour change 6. Record the final burette reading and calculate the titre volume 7. Repeat until 2 concordant results are reached

Question 27

What's one way of reducing uncertainties in a titration?

Answer 27

Increase the titre volume

Question 28

What is an oxidising agent?

Answer 28

Accepts electrons from what is being oxidised, therefore it gains electrons and is reduced

Question 29

What is an oxidising agent?

Answer 29

Accepts electrons from what is being oxidised, therefore it gains electrons and is reduced

Question 30

What is a reducing agent?

Answer 30

Donates electrons to what is being reduced, therefore it loses electrons and is reduced

Question 31

What is a disproportionate reaction?

Answer 31

When a species is both oxidised and reduced

Question 32

What is uncertainty?

Answer 32

A reading for a specific instrument is said to be plus or minus half of the smallest division.

Question 33

What is the equation for uncertainty?

Answer 33

uncertainty/reading *100 uncertainty/reading *100*2 only if there's 2 readings

Question 34

What is the method to calculating an unknown concentration?

Answer 34

1. From the titration results calculate the amount of moles of one of the alkali 2. Using the equation find the moles of the acid 3. Work out the unknown concentration

Question 35

What are the steps to identifying an unknown carbonate?

Answer 35

1. Calculate the amount of moles of HCl that reacted, using the mean titre and concentration of HCl 2. Determine the amount of X2CO3 that reacted using the equation 3. Scale up to find the amount of X2CO3 in the 250cm3 solution prepared 4. Find the Mr of X2CO3, then find the Mr of X