Unit 4: Acids, Bases, And Salts (3) Flashcards
A solution with an accurately know concentration is called a____ or a _____
Standard solution
Standardized solution
A primary standard is…
A substance which can be obtained in a pure stable form (Doesnt absorb water or carbon dioxide). It must also have a known molar mass which can be used to prepare a solution of known concentration
How can you create a standard solution that is not a primary standard?
Titrate a base with a primary standard (or other solution of known concentration) to find the exact concentration of the base.
What are the two acidic primary standards most commonly used?
Potassium hydrogen phthalate (KHC8H4O4)
Oxalis acid dihydrate (H2C2O4•2H2O)
Potassium hydrogen phthalate (KHC8H4O4), is ____ in its reaction with NaOH and the best indicators to use with it are ______ or ______.
Monoprotic
Phenolphthalein
Thymol blue
Oxalis acid dihydrate (H2C2O4•2H2O) is _____ in its reaction with NaOH and the best indicator to use with it is _____.
Diprotic
Phenolphthalein
The most common basic primary standard is _____.
Sodium carbonate (Na2CO3)
Sodium carbonate (Na2CO3) is _____ in its reaction with HCl and the best indicator to use for it is_____.
Diprotic
Methyl orange
In order to carry out a titration, you must have a solution with an accurately known ______.
Concentration
When ever an acid is added to a base the H+ available in the ____ react with the _____ in the base. When no excess ___ or ____ remain in solution, the solution is ____.
Acid OH- H+ OH- Neutral
The process of arriving at a neutral solution is called ___.
Neutralization
What is titration?
Titration is the process of adding a solution of known concentration and known volume (often a base) to a solution with a known volume and unknown concentration (often an acid) to find the unknown concentration
At equivalence point the moles of H+ equals to…?
The moles of OH-
What is the purpose of a buffer?
To maintain a relatively constant pH when either a small amount of acid or base is added
Buffers have an equilibrium between…
a weak acid (or weak base) and its conjugate weak base (or conjugate weak acid).
Buffers only work when a ____ amount of acid or base is added
Small
You need a minimum of ____ weak acid/base and its conjugate base/acid to create a buffer
1 M [ ]
%purity=…?
((Mass of active ingredient) / (mass of sample)) X 100
What kind of titrations are never done?
Weak acid weak base titrations
What are the 4 main regions of pH vs volume graphs
A. Initial pH (before titration)
B. pH before equivalence point
C. pH at equivalence point
D. pH after equivalence point
A primary solution is made from scratch and the [calculated] is equal to…?
[actual]
Acid rain has a pH of 5-6. What is the pH of acid rain?
4-5
What is the main cause of acid rain?
What natural phenomenon can also cause acid rain?
The burning of fossil fuels
And lighting
What are 4 side effects of acid rain
1-leach out nutrients from soil (killing plants)
2- damage lakes (kills all stuff in the lake - Quebec)
3- affects human health (asthma and respiratory diseases)
4- breaks down buildings (destroys concrete over time)
Name 4 ways to prevent acid rain?
1-higher smoke stacks/scrubbers
2- toughen up on pollution laws
3-alternative fuels and energy sources
4- better made cars (pollute less)
Only ionic metal oxides form ___ solutions
Basic
Covalent oxides form ____ solutions
Acidic
A ____ is a weak ____ acid or base with different colours for its conjugate acid and conjugate base forms
Indicator
Organic
An indicator is in its ____________ form when in highly acidic solutions
Conjugate acid
An indicator is in is ________ form when in highly basic solutions
Conjugate base
In acidic solutions [HIn] is _____ (,=) [In-]
Greater than (>)
In basic solutions [HIn] is _____ (,=) [In-]
Less than (
The [H3O+] at which an indicator changes colour equals to..?
The Ka for the indicator
An indicator is at the midpoint of of its colour change when the pH of the solution equals…?
The pKa of the indicator
