acids and bases

Question 1

what are the qualities of acid

Answer 1

Acids have a pH below 7
They are corrosive and sour tasting
In acidic conditions blue litmus paper and methyl orange turns red
Acids are proton donors as they ionize in solution producing protons, H+ ions
These H+ ions make the aqueous solution acidic

Question 2

what are the qualities of bases

Answer 2

Bases have pH values of above 7
They taste bitter and chalky
Bases turn litmus paper blue and methyl orange yellow
A base which is water-soluble is referred to as an alkali
They are metal hydroxides
Bases are usually oxides or hydroxides of metals, except for ammonia
Bases (alkalis) are proton acceptors as they ionize in solution producing OH– ions which can accept protons
These OH– ions make the aqueous solution alkaline

Question 3

formula of stoichometry for neutralisation reaction

Answer 3

Ma Va = Mb Vb

M =molarity/concentration
V= volume in cm3
a=acid
b=base

Question 4

what are the steps in analytical titration

Answer 4

Measure amount of unknown concentration solution and place in beaker
Add indicator
Titrate using known concentration until the endpoint is reached
Calculate the concentration of the solution in the beaker

Question 5

methods to prepare salts

Answer 5

Titration
Titration of acid and alkali to make salt and water
The salt is a soluble salt so you have to crystallise it
The Alkali is the solution

Evaporation method
Needs excess addition of insoluble base/metal with acid
Need to filter then crystallise it
Precipitation
Mixing two solutions of soluble salt to make an insoluble salt
Need to filter then wash/dry it

Question 6

solubility rule

Answer 6

All K+, Na+, NH4+ = Soluble​
All Ethanoate, CH3COO- & Nitrate, NO3- = Soluble​
All Carbonate, CO32- = Insoluble, except K+, Na+, NH4+​
All Halides (Cl-,Br-,I-)= Soluble, except Ag+, Pb2+
All SO42- = Soluble, except Pb2+, Ba2+, Ca2+

Question 7

ways to make soluble salts

Answer 7

• acid+alkali titration

- acid+excess insoluble solid (reactive metal, base or carbonate)

Question 8

ways to make insoluble salts

Answer 8

This involves mixing solutions of two soluble salts that between them contain the ions that make up the insoluble salt. It is made by two methods

• direct combination
• precipitation

Question 9

how to make a sulfate

Answer 9

use sulfuric acid

Question 10

how to make a chloride

Answer 10

use hydrochloric acid

Question 11

what is a strong acid/base

Answer 11

Strong acids and bases ionize completely in water, producing solutions of very low pH for an acid or very high pH for a base

Question 12

what is a weak acid/base

Answer 12

Weak acids and bases partially ionize in water and produce pH values which are closer to the middle of the pH scale

Question 13

what is example of strong acids

Answer 13

Strong acids include HCl and H2SO4 and strong bases include the Group I hydroxides

Question 14

what is an example of weak acids

Answer 14

Weak acids include organic acids such as ethanoic acid, CH3COOH (aectic acid) and weak bases include aqueous ammonia

Question 15

equilibrium in weak acids and alkalis

Answer 15

For both weak acids and bases, there is usually an equilibrium set-up between the molecules and their ions once they have been added to water
Example of a weak acid: propanoic acid
CH3CH2COOH ⇌ H+ + CH3CH2COO-
Example for a weak base: aqueous ammonia
NH3 + H2O ⇌ NH4+ + OH-
In both cases the equilibrium lies to the left, indicating a high concentration of intact acid / base molecules, with a low concentration of ions in solution

Question 16

acid + metal

Answer 16

Acids react with metals to form salt and hydrogen

Question 17

acid + base

Answer 17

Acids react with bases to form salt and water

Question 18

acid + carbonate

Answer 18

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

Question 19

bases + ammonium salt

Answer 19

Bases react with ammonium salts to form salt, water and ammonia

Question 20

what are some indicators

Answer 20

Universal indicator is a mixture of indicators. It is useful because it shows a range of colours from pH 1–14.​
pH meter
Direct distinction between acid and base
Litmus paper
Direct distinction between acid and base
Universal Indicator
DIfferent shades for each pH

Question 21

what is pH + formula

Answer 21

Stands for potential of hydrogen

Formula is ㏒10(value of mol)

Question 22

what are oxides

Answer 22

An oxide is a compound of oxygen and another element

Question 23

what are the four groups of oxides

Answer 23

acidic oxides
basic oxides
amphoteric oxides
neutral oxides

Question 24

properties of acidic oxides

Answer 24

Acidic oxides are oxides of non-metals (noble gases don’t form acidic oxides)
Acidic oxides are often gases at room temperature
Acidic oxides react with water to form acidic solutions
E.g. sulfur trioxide + water -> sulfuric acid (so3+h20-> H2SO4)
Acidic oxides react with bases and alkalis to produce salts and water
E.g carbon dioxide + sodium hydroxide -> sodium carbonate + water (CO2+2NaOH -> Na2CO3 + H2O)

Question 25

properties of basic oxides

Answer 25

Basic oxides are oxides of metals, with exception of ammonia (non-
metal base)
Basic oxides are often solids at room temperature
Most basic oxides are insoluble at room temperature
Basic oxides react with acids to produce salt and water
This is known as a neutralisation reaction
E.g magnesium oxide + hydrochloric acid -> magnesium chloride + water (MgO + 2HCl -> MgCl2 + H2O)
When a metal oxide reacts with an acid, the atoms are rearranged

Question 26

properties of amphoteric oxides

Answer 26

Amphoteric oxides are oxides of metals
Some examples of metals that form amphoteric oxides are aluminum, germanium and zinc
They can behave as acidic oxides or basic oxides
They react with acids and alkalis to produce salts
E.g aluminium oxide + hydrochloric acid -> aluminium chloride + water
E.g aluminium oxide + sodium hydroxide -> sodium illuminate + water

Question 27

properties of neutral oxides

Answer 27

Neutral oxides are non-metals that form oxides that show neither basic nor acidic properties
They are insoluble in water

Question 28

what are the neutral oxides?

Answer 28

• water
• carbon monoxide
• nitric oxide/nitrogen monoxide