7 - Acids, Bases & Salts Flashcards
Def. Acid
A substance that gives away/donates hydrogen ions (H+). This only happens in a solution with water. H+ ions are known as protons.
Def. Base
A substance that recives/accepts hydrogen ions (H+), or protons, from acids (and they are not necesarily soluble in water)
Def. Alkali
A soluble base that accepts protons from acids
Def. Strong Acid
An acid with completely disassociated into ions in a solution where no particle in the acid remain molecules
Def. Weak Acid
An acid with partially disassociated into ions in a solution where most particles in the acid remain molecules
What are the 3 indicators for Acids and Bases?
- Litmus paper
- Thymolphalein
- Methyl Orange
What does Litmus paper reveal?
- When in an acid, it turns red
- When in a base, it turns blue
- When in a neutral colour, it remains the same.
There are two colours - red and blue litmus paper
What does Thymolphalein reveal?
- It turns blue when reacting with an base
- Otherwise, it remains colourless
It starts of as transparent
What does Methyl Orange reveal?
- It turns red when reacting with an acid
- It turns yellow when reacting with anything else such as neutral or bases
It starts of as orange
Why will strong acids react faster than weak acids?
They have a larger concentration of hydrogon ions/protons
What is produced when an acid and a metal react?
Acid + Metal → a salt + H2
What is produced when an acid and a base react?
Acid + Base → a salt + H2O
What is produced when an acid and a carbonate react?
Acid + Carbnate → a salt + H2O + CO2
What is the formula for ethanoic acid?
CH3CO2H
What are the 4 acids you are required to know?
- Hydrochloric acid (HCl)
- Sulfuric acid (H2SO4)
- Nitric acid (HNO3)
- Ethanoic acid (CH3CO2H)
What solutions do most non-metal oxides form?
Acidic solutions
What solutions do most metal oxides form?
Basic solutions
What type of oxide does Hydrogen form?
A neutral oxide, aka H2O/Water
What type of oxides do Aluminium and Zinc form?
Amphoteric oxides
What is an amphoteric oxide?
And which two elements are used to form them?
They are oxdes that react with both bases and acids - such as Aluminium or Zinc
What is the general equation for neutralisation?
H+ + OH- = H2O
This is the ionic equation for all reactions between acids and bases
What is the pH scale and what does it stand for?
A measurement of hydrogen cation concentration
Number n on the scale stands for 1 x 10-n concentration of H+
What are solutions with a higher pH called?
They are Basic, and Alkaline
What is the pH for neutral?
7
What are solutions with a lower pH called?
Acidic
What is the solubility rule for nitrates?
All nitrates are soluble
What is the solubility rule for Chlorides?
All common Chlorides are soluble, except for lead and silver chloride
What is the solubility rule for Sulfates?
All common Sulfates are soluble, except for barium, calcium and lead sulfate
What is the solubility rule for Hydroxides?
Sodium , potassium , ammonium hydroxide are soluble, calcium hydroxide is partially soluble, and the rest of the common hydroxides are insoluble
What is the solubility rule for carbonates?
Sodium, potassium, and ammonium carbonate are soluble, while all other common carbonates are insoluble
What is the solubility rule for sodium, potassium, and ammonium salts?
They are all soluble
What reaction can be used to create a soluble salt, and how would you obtain the crystallised salt?
The reaction of an acid with excess metal will create a soluble salt.
The excess metal can then be filtered away and the filtrate can be boiled to get rid of water.
When attempting to create a pure salt using excess metal and acid, why is it important to use excess metal and not acid?
So that acid does not remain, and mix with the salt solution, rendering it impure
How do you obtain a salt from an alkali (which is soluble)
You cannot obtain it using excess alkali because the ecxess will dissove in the slution and cannot be fltered. You use a graduated pipette and pipette filler to obtain a specific volume of aqueous alkali, then pour that into a conical flask. Place this beneath a burette flled with acid and pour universl indicator into the flask. Pour acid drop by drop until the solution in the flash goes green (neutral).
Note the volumes used, then repeat experiment without indicator.
How does precipitation work?
Two solutions are mixed together to form an insoluble solid called the precipitate.
How do you isolate a precipitate from it’s solution?
You
What are the 3 steps to make and isolate a precipitate?
- Mix the reactents to make the ppt, and stir (e.g. with glass rod)
- Filter the mixture and collect the residue
- Wash the precipitate with distilled water to get rid of unwanted substances and then dry with filter paper
