Acids, Bases And Salts Flashcards
What are some everyday examples of acids?
Citric acid- lemons
Ethanoic acid- vinegar
Sulfuric acid- battery acid
List some everyday examples of bases
Cleaning products
Metal oxides or metal hydroxides
What do acids do when dissolved in water?
Release hydrogen ions
List some properties of acids
Corrosive
Sour taste
pH below 7
List some properties of bases
Slippery/soapy feel
Bitter taste
pH above 7
What do alkalis do when dissolved in water?
Release hydroxide ions
What are the symbols for the following hazards?
Explosive Flammable Oxidising Gas under pressure Corrosive Acutely toxic Moderate hazard Health hazards including carcinogens Hazardous to the environment
Exploding orb Fire Burning orb Gas cylinder Test tubes dripping onto hand and bench Skull and crossbones Exclamation mark Star-shaped exploding throat Dead fish and dead tree
What is an indicator?
A chemical that gives a colour change in acidic, alkaline and neutral solutions.
What is the colour change present in phenolphthalein?
Colour in acid: colourless
Colour in alkali: Pink
Colour in neutral: colourless
What is a pH meter?
Devices that can record a pH to 2 decimal places.
How do strong acids/alkalis compare to weak acids/alkalis when it comes to ionisation?
A strong acid/alkali ionises completely in water
A weak acid/alkali ionises partially in water
What is a base?
A base is a substance that will react with an acid producing a salt and water
What is an alkali?
A soluble base
What is the difference between strength and concentration?
Strength is the measure of the amount of ionisation and is measured by pH
Concentration is a measure of the number of moles of acid/alkali molecules dissolved in 1dm3 of water.
What is neutralisation?
Neutralisation is the reaction between an acid and an alkali producing a salt and water
What is the ionic equation for neutralisation?
H+ (aq) + OH- (aq) -> H2O (l)
Give some real life examples of neutralisation reactions
Indigestion tablets
Acidic soils covered with lime
Lakes affected by acid rain get lime
Nettle stings rubbed with doc leaves.
What is strength?
A measure of the amount of ionisation and is measured in pH
What is concentration?
A measure of the number of moles of acid/alkali molecules dissolved in 1dm3 of water and is measured in mol/dm3.
What is a salt?
A compound formed when some or all of the hydrogen ions in an acid are replaced by metal ions or ammonium ions.
What salt does hydrochloric acid produce?
Chlorides, containing Cl- ions
What salt does sulfuric acid produce?
Sulfates, containing SO42- ions
(4 under 2- above)
What salt does nitric acid produce?
Nitrates, containing NO3- ions
What salt does ethanoic acid produce?
Ethanoates, containing CH3COO- ions
What forms from the following reactions? Acid + metal —> Acid + base —> Acid + alkali —> Acid + carbonate —> Acid + hydrogencarbonate —> Acid + ammonia —>
Salt + hydrogen Salt + water Salt + water Salt + water + carbon dioxide Salt + water + carbon dioxide Ammonium salts
What does copper (II) oxide look like?
Black solid
What does Copper (II) carbonate look like?
Green solid
What does hydrated copper (II) sulfate look like?
Blue crystals
What does copper (II) salts in solution look like?
Blue solution
What do group 1, group 2, aluminium and zinc compounds look like?
White solids and if they dissolve in water they give colourless solutions
What are the methods of drying salts?
Place in a dessicator
Place in a low temperature oven
Dry between 2 sheets of filter paper
How would you prepare salt from acid and insoluble bases?
Prescribed practical C3: investigate the preparation of soluble salts — preparation of copper sulfate
- Measure 25cm3 of dilute sulfuric acid and place in a beaker
- Warm the acid for a short time (don’t allow to boil)
- Add copper carbonate to the sulfuric acid and stir. Continue adding copper carbonate until there is no further reaction and there is excess copper carbonate present.
- Allow to cool - then filter the mixture and collect the filtrate solution in an evaporating basin.
- Heat the filtrate solution in the evaporating basin on a tripod and gauze until the volume is about one half of what it was originally
- Allow the basin to cool and the crystals will form.
- When the crystals have formed, filter if necessary and dry.
How would you prepare soluble salt from acid and soluble base (alkali) by titration method.
(Prescribed practical C3: investigate the preparation of soluble slats — Preparation of sodium chloride)
Method 1
- Fill the burette with hydrochloric acid
- Using the pipette and pipump place 25cm3 of sodium hydroxide solution (NaOH, 0.1M), into a beaker
- Add 3 drops of phenolphthalein to the conical flask- the solution should turn pink
- Carefully add the hydrochloric from the burette into the conical flask (swirl gently)
- Stop adding the hydrochloric acid when the indicator turns colourless.
- Record the volume added by carefully reading the burette.
- Carry out the reaction again, running the acid in steadily until close to the end point when it is added in very small aliquotes (0.1 ml) until the colour change is observed, providing a more accurate quantity.
- The reaction is carried out one more time, this time without the indicator and using the accurate quantity of acid.
- The solution from the conical flask is poured into the evaporating basin.
- Place the evaporatingbasin onto a tripod and gauze and heat gently using a Bunsen Burner until 1/2 of the solution remains.
Method 2
- After step 5, add 2 spatulas of decolourising charcoal to the conical flask.
- Heat gently, using tripod, gauze Bunsen burner and heatproof mat (do not boil)
- Allow to cool slightly, then filter the mixture into an evaporating basin.
- Place onto a tripod and gauze and heat gently using a Bunsen Burner until about 1/2 of the solution remains.
- Leave to cool and crystallise. Remove crystals and dry.
What is the name given to the solid trapped by filter paper?
Residue
What is the name given to the filtered solution?
Filtrate
What is the common name for calcium hydroxide solution?
Limewater
