Chapter 17 - ACIDS AND BASES Flashcards
Define Acid
A substance capable of producing hydrogen ions (H+) in solution
(Arrhenius Model)
Or Donating a hydrogen ions (Brønsted-Lowry Model)
Define Base
A substance capable of producing hydroxide ions (OH-) in solution (Arrhenius Model)
Or accepts a proton (Brønsted-Lowry Model)
Define Acidity
Acidity is the concentration of H+ ions in an aqueous solution.
Acidity is measured using the pH scale
Hydrochloric Acid formula and use
HCl
*Stomach Acid
Nitric Acid Formula and use
HNO3
- manufacture of fertilisers, Dyes and explosives
Sulphuric Acid Formula and use
H2SO4
*Car batteries, manufacturing of detergent and fertiliser
Carbonic Acid Formula and use
H2CO3
*carbonated soft drinks
Phosphoric Acid Formula and use
H3PO4
*some soft drinks and manufacture of fertiliser
Citric Acid Formula and use
C6H10O7
*juice of citric fruits Eg lemons
Ascorbic Acid Formula and use
H8C6O6
*found in Citrus fruits (vitamin C)
Potassium Hydroxide Formula
KOH
Sodium Hydroxide Formula and use
Na(OH)2
- Used in drain and oven cleaners, soap making
Ammonia (base) formula and use
NH3
Used in household cleaners, fertilisers and explosives
Sodium Carbonate formula
NaCO3
Magnesium Hydroxide
Mg(OH)2
What is an Alkali?
A soluble base is called an alkali
Formula of Calcium hydroxide and use
Ca(OH)2
- found in cement and mortar, used in garden lime to adjust pH of soil
Formula of Ethanoic Acid/ Aecetic Acid and use
CH3COOH
*a component in vinegar
What are some properties of an Acid?
- Turns litmus paper Red
- Tends to be Corrosive
- Tends to taste sour
- Reacts with Bases (and neutralisation occurs)
- Relatively low pH (0-7)
- Conducts and Electric Current in solution
What the properties of a base?
- Turns litmus paper blue
- Tends to be Caustic (corrosive for a Base) and SLIPPERY
- Tends to taste Bitter
- Reacts with Acids (and neutralisation occurs)
- Conducts an electric current in solution
Why are Bases effective cleaners? Main components in a cleaning product.
They react with FATS or OILS to produce water soluble soaps
Body excretes acid products therefore base will neutralise the environment cleaning
Why are Bases slippery?
Bases are slippery because they react with Fats on skin to produce a soap
What is litmus paper?
- Litmus is a water-soluble mixture of different dyes extracted from lichens.
- It is often adsorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity
What is an Indicator?
Indicators are chemicals that change colour, depend on the acidity of the solution.
Eg plant extracts, Litmus in litmus paper, Cabbage, Rose petals and blackberries
What is a Universal Indicator?
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions.
**Colours shown on the universal indicator can be used to determine the approximate pH of solutions
What is a pH scale?
pH is a scale used to SPECIFY THE ACIDITY OR BASICITY OF AN AQUEOUS SOLUTION
At room temp (25°C) pure water is a pH of 7
Defined in terms of 25°C
Acid = pH of 0-7
Base = pH of 7-14
Negative logarithm
- as the pH of a DECREASES the concentration of H+ INCREASES
What is ionisation
Ionisation is
- process that involves the formation of ions VIA the removal of one or more electrons from an atom or ion
- the reaction of a molecular substance with a solvent to form ions in solution