Topic 4 Acids and alkalis Flashcards
- What term describes a substance that attacks metals, stonework and skin?
corrosive
- Name an acidic solution found in the kitchen.
vinegar or fruit juice, etc.
- Name an alkaline solution used in the kitchen.
bleach or oven cleaner or soap, etc.
- What type of substance turns litmus paper red?
acid
- How does an indicator show the acidity or alkalinity of solutions?
by changing colour
- What pH values represent alkaline solutions?
above 7 or 8 to 14
- What happens in all chemical reactions?
new substances are formed
- What kind of reaction occurs between an acid and an alkali?
neutralisation
- What do you call a solution that is neither acidic nor alkaline.
neutral
- Give the name and formula of a common laboratory acid.
hydrochloric acid (HCl) or nitric acid (HNO3) or sulfuric acid (H2SO4), etc.
- Which ion is in excess in all acidic solutions?
hydrogen ions or H+ ions
- Which ion is in excess in all alkaline solutions?
hydroxide ions or OH– ions
- What scale is used for measuring acidic and alkaline properties?
the pH scale
- Name three examples of acid/alkali indicators apart from universal indicator.
litmus, methyl orange and phenolphthalein
- What would you use to measure pH to one decimal place?
a pH meter
- What pH values are acidic?
below 7
- What colour is phenolphthalein in a solution with a pH of 2?
colourless
- What happens to the pH as the H+ ion concentration increases?
it decreases
- If a solution has the same concentration of hydrogen ions as hydroxide ions, how is it described?
neutral or pH = 7
- If 2 g of salt is dissolved in 250 cm3 of solution, what is its concentration in g dm–3?
8 g dm–3
- What word describes a solution that contains a large amount of solute in a small volume of solvent?
concentrated
- How can a solution be made more dilute?
by adding solvent/water
- If 24 g of acid is dissolved in 600 cm3 of solution, what is its concentration in g dm–3?
40 g dm–3
- What happens when strong acid molecules dissolve in water?
they dissociate completely into ions
- What kind of reaction occurs between an acid and a base?
neutralisation
- What happens to the pH of an acid as it reacts with a neutraliser?
pH increases
- What is formed when an acid reacts with a base like a metal oxide?
salt + water
- What acid would be used to make zinc sulfate from zinc oxide?
sulfuric acid (sulphuric acid makes sulphates!)
- What process can be used to separate an insoluble solid from a liquid?
filtration
- How can a sample of a dissolved salt be obtained from a salt solution?
evaporation of the water
- In general, what is the pH of an alkaline solution?
greater than 7
- Which ions, hydrogen ions or hydroxide ions, are released by alkalis in solution?
hydroxide ions (OH-)
- What colour is litmus solution in acidic solutions?
red
- What name is given to substances that react with acids to form a salt and water only?
bases (bases are metal oxides and hydroxides, soluble bases are alkalis)
- Which salt is formed when copper oxide reacts with sulfuric acid?
copper sulfate
- What type of reaction happens between an acid and a base?
neutralisation
- What type of solution has a pH of 7?
neutral
- Name the acid that has the formula HCl.
hydrochloric acid
- What colour is phenolphthalein in alkaline solutions?
pink (it is colourless in acid conditions)
- What is the formula for sulfuric acid?
H2SO4
- Name the salt produced when sodium hydroxide reacts with hydrochloric acid.
sodium chloride
- Which ions, hydrogen ions or hydroxide ions, are released by acids in solution?
hydrogen ions (H+)
- What substance, other than a salt, is produced when an alkali neutralises an acid?
water
- What name is given to substances that are soluble bases?
alkalis
- What is the formula for hydrochloric acid?
HCl
- What type of solution has a pH above 7?
alkaline
- What colour is phenolphthalein in acidic solutions?
colourless – not ‘clear’
- Name a piece of apparatus used to measure volumes of liquid.
measuring cylinder/pipette/burette
- Name the separation method used to produce crystals from a solution.
crystallisation
- Name the acid needed to make ammonium nitrate.
nitric acid
- Which acid can be used to make copper sulfate?
sulfuric acid
- Which base can be used to make copper sulfate?
copper oxide
- Which substance is needed to complete the general equation: acid + base makes salt + …?
water (BASHO)
- What is the formula of nitric acid?
HNO3
- What is the name of the salt formed from zinc oxide and hydrochloric acid?
zinc chloride
- What is the formula of the salt formed from calcium oxide and hydrochloric acid?
CaCl2
- Which ions are present in large quantities in aqueous solutions of all acids?
H+ Hydrogen ions
- Which ions are present in large quantities in aqueous solutions of all alkalis?
OH– Hydroxide ions
- Which gas is formed when dilute hydrochloric acid reacts with magnesium?
hydrogen (MASH)
- Which gas is formed when dilute hydrochloric acid reacts with magnesium carbonate?
carbon dioxide (CASHOCO)
- What acid can be used to make copper chloride?
hydrochloric acid (hydrochloric acid makes chlorides)
- What gas is given off when magnesium reacts with dilute sulfuric acid?
hydrogen (MASH)
- How do you identify Hydrogen gas?
gives a squeaky pop with a lighted splint
- What is seen when magnesium is added to dilute sulfuric acid?
effervescence/fizzing/bubbles (yes you know this is hydrogen, but you can not see that!!)
- What is the formula of magnesium sulfate?
MgSO4
- What gas is produced when copper carbonate is added to dilute nitric acid?
carbon dioxide (CASHOCO)
- How do you test for Carbon Dioxide?
it turns limewater milky
- What is the formula of the salt produced when copper carbonate reacts with nitric acid?
(Cu(NO3)2)
- Sodium chloride dissolves in water to form a solution. Which is the solute?
sodium chloride
- What do we call the liquid that dissolves a solute to form a solution.
solvent
- What does methyl orange turn in acids and in alkalis
Red in acids Yellow in alkalis
If a pH 5 has 10 H+ ions how many H+ ions are in a pH of 4?
100 H+ Times by 10 when the pH gets lower Divide by 10 when the pH gets higher
What is the rate of reaction calculation?
1/time
- What is BASHO?
base + acid = salt + water
- What is MASH?
Metal + Acid = salt + hydrogen
- What is CASHOCO?
Metal carbonate + acid = salt + water + carbon dioxide
How do you prepare an insoluble salt from a precipitation reaction?
Simply mix the two solutions together, filter off the precipitate (salt) and dry.
- What is the precipitate in this reaction? Lead nitrate + potassium iodide
= lead iodide + potassium nitrate Lead iodide is the precipitate as potassium nitrate is soluble
The lower the pH the..
Stronger the acid.
The higher the pH the…
Weaker the acid.
What happens to the molecules of strong acids in water?
Their molecules dissociate (break up) completely into ions when they dissolve in water and produce high concentrations of H+ ions.
What happens to the molecules of weak acids in water?
They don’t dissociate (break up) completely into ions in solution.
Write the balanced ionic equation for neutralisation?
H+ (aq) + OH- (aq) = H20 (l)
- Explain titration experiments, how you would go about them?

What is used to place a fixed volume of a solution into a conical flask in titration?
A pipette.
A buiret is used to add variable amount of solution volume.
Learn the solubility rules. What are they?
Used in precipitation reactions to find out the precipitate.

In an ionic equation what are the spectator ions?
Ions that don’t change during the reaction.
When writing ionic equations what is oxidised at what is reduced. (OILRIG)
Oxidation is loss of electrons
Reduction is gaining of electrons
what is the difference in concentration oh H+ in different pH’s?

A concentrated solution contains…
A lot of dissolved solute per unit volume.
A dilute solution contains…
Only a small amount of solute.
What is the concentration calculation?
Concentration (grams per decimetre cubed, g dm^-3) = amount of dissolved (in grams)/volume of solution(dm^-3)