2f Acids, Alkalis and titrations Flashcards
What is the formula for hydrochloric acid?
HCl
What is the formula for Sulphuric acid?
H2SO4
What is the formula for nitric acid?
HNO3
What is the formula for Phosphoric acid?
H3PO4
What does basicity mean?
How many hydrogen ions can be replaced in an acid molecule
What does Methyl orange measure?
It can only show whether a substance is acidic or alkaline
acidic - red
alkaline/neutral - yellow
What does Phenolphthalein measure?
It can only show whether a substance is alkaline or not
acidic/neutral - colourless
alkaline - pink
What does Universal Indicator measure?
It can measure whether something is an acid or alkaline. And it can tell you how strong and acid or alkali is
Why can acids be proton donator?
Because a hydrogen ion only has a proton subatomic particle.
Hydrogen atom - p - 1
e - 1
n - 0
Hydrogen ion - p - 1
e - 0
n - 0
What is the basicity of hydrochloric acid?
Monobasic (one H+)
What is the basicity of sulphuric acid?
Monobasic (One H+)
What is the basicity of Nitric acid?
Dibasic (Two H+)
What is the basicity of Phosphoric acid?
Tribasic (Three H+)
What is basic?
The term used to describe oxides and hydroxides of metals (base). Bases can be described as proton acceptors (in other words they accept the H+ ion released by acids). Some bases are soluble and will dissolve in water. A soluble base is called an alkali.
What is the formula of Sodium Hydroxide?
NaOH
What is the formula of Potassium Hydroxide?
KOH
What is the formula of Calcium Hydroxide?
Ca(OH)₂
Ca2+ OH-
Ca(OH)2
What is a neutralisation reaction?
When an acid is added to an alkali a neutralisation reaction occurs
H+(aq) + OH(aq) -> H2O(l)
What is a chemical salt?
A chemical salt is a substance formed when one or more hydrogen atoms in an acid is replaced by a metal
What is the salt name for hydrochloric acid?
chloride (Cl-)
What is the salt name for nitric acid?
nitrate (NO3-)
What is the salt name for sulfuric acid?
sulfate (SO42-)
What is the salt name for phosphoric acid?
phosphate (PO43-)
What chloride salts are soluble?
All Soluble (except silver or lead chloride)
What sulphate salts are soluble?
All soluble (except calcium, barium or lead sulphate)
What sulphate salts are nitrates?
All soluble
What sulphate salts are carbonates?
Insoluble (except sodium or potassium carbonate)
What is an acid?
A substance that contains replaceable hydrogen atoms with form H+ (aq) ions when the acid is dissolved in water. It has a pH less than 7.
What is a base?
Substance that neutralises an acid to produce a salt + water. These are usually solid metal oxides or hydroxides
What is an alkali?
A base that is soluble in water and produces OH-(aq) ions. It has a pH greater than 7.
What is a salt?
Compound made from the reaction of an acid and a base
How to do the titration method?
1) A burette which has first been rinsed with distilled water is filled with hydrochloric acid using a funnel; remove the funnel afterwards
2) Measure out exactly 25.00cm3 of dilute sodium hydroxide and add it to a conical flask. An indicator is added to the solution being analysed. This will change colour when the reaction is complete. We are using methyl orange or Phenolphthalein indicator.
3) Take the initial reading of the burette and record it in your results table. Add the acid from the burette to the contents of the flask, while the flask is swirled constantly. Near the end point the solution is added drop by drop.
4) At the end point from the indicator changes colour. Record the final volume of the acid and record it in your results table. Work out the total volume of the acid added. This is the titre. Wash out the conical flask with distilled water and repeat the titration until 2 of the readings agree within 0.10cm3.
How to obtain pure dry chemical salt using titration method?
Once the exact volume of acid is needed to neutralise the fixed volume of alkali is found:
1) Repeat the titration using exact volumes from experiment and NO INDICATOR.
2) Pour the salt solution into an evaporating basin and gently heat (To remove water)
3) Once the crystallization Point is reached (solid formed when solution placed on a cold glass rod), stop heating
4) Leave in a warm oven to dry