Acids Flashcards
Give the formula of the 7 weak acids you need to know
- Hydrochloric acid = HCl
- Sulfuric acid = H2SO4
- Nitric acid = HNO3
- Phosphoric acid = H3PO4
- Methanoic acid = HCOOH
- Ethanoic acid = CH3COOH
- Propanoic acid = CH3CH2COOH
Give the definition of an acid
(Proton doner)
- Release H+ ions in aqueous solutions
Give the definition of a strong acid
(one way reaction)
- Completely dissociate when dissolved in water.
Give the definition of a weak acid
(reversible reaction)
- Only slight dissociate when dissolved in water, giving an equilibrium mixture
What is formed when an acid dissociates in water?
A proton (H+ ion) and a negative anion.
Are carbonates, hydroxides and oxides bases? Could they also be alkalis?
Yes, anything that reacts with an acid is a base, however to be an alkali it must react or dissolve in water to form OH- ions and react with acids.
Give the definition of a base
A substance which neutralises an acid (proton acceptor)
Give the definition of an alkali
A soluble substance that releases OH- ions in aqueous solutions
State whether soluble metal oxides, soluble hydroxides and ammonia reacts or dissolves in water and if so what does it form?
- Soluble metal oxides react with water as the oxide ions react with water to form OH- ions e.g. Na2O + H2O –> 2Na+ + 2OH-
- Soluble hydroxides just dissociate in water to form OH- ions e.g. NaOH —> Na+ + OH-
- Ammonia reacts with water to form ammonium ions and OH- ions e.g. NH3 + H2O —> NH4+ + OH-
Give the definition of a salt
- A chemical compound formed from the reaction of an acid and a base, with all or part of the hydrogen of the acid is replaced by a metal or other cation e.g. NH4+
Give the reaction of when an acid reacts with a base, when an acid reacts with an alkali, when an acid reacts with a carbonate and when an acid reacts with ammonia
- acid + base —> salt + water
- acid + alkali —> salt + water
- acid + carbonate —> salt + carbon dioxide + water
- acid + ammonia —> ammonium salt
Does salt dissolve in water; if so what does it form?
- Yes
- It will dissolve to form aqueous ions e.g. NaCl —> Na+ + Cl-
What is an ionic equation and give all the steps to creating an ionic equation
- An ionic equation will only show the ions or species that change state in a reaction, and they omit (leave out) those ions that are not involved in the reaction
- assign correct state symbols
- separate anything aqueous into its ions
- cancel out anything that appears on the side of the equation (anything that stays the same)
- write the ionic equation
Give the 7 steps for making a standard solution
- Weigh out an accurate mass of solid in a clean and dry beaker
- Add enough deionised water to dissolve the solid, stirring with a glass rod
- Transfer the solution to a volumetric flask using a funnel
- Rinse the beaker, stirring rod and funnel with deionised water and transfer washings to to volumetric flask
- Add deionised water to volumetric flask to make up to the graduation mark. Use a dripping pipette when close to the mark. Going beyond the mark will result in an unknown concentration, make sure the bottom of the meniscus is on the mark
- Stopper the flask and invert to mix thoroughly to ensure a homegenous solution
- Use concentration=mass/volume to work out concentration
How do I do a titration reaction in 7 steps?
- Rinse burette with deionised solution, then rinse with standard solution, then fill the burette including the jet with standard solution. Take initial reading and record to two d.p. ending in 5 or 0
- Rinse pipette with deionised water, then rinse with unknown concentration solution, and then transfer 25cm^3 of the solution from the beaker into conical flask using pipette
- Add 3-4 drops of Phenolphthalein in (the end result will be very pale pink) and place under the burette
- Remove filter funnel and add the solution from the burette, with constant swirling of the conical flask, until the solution is a very pale pink (indicates neutralisation), add deionised water to sides of conical flask to ensure all of solution has reacted
- Write down burette reading to 2 d.p. ending in 0 or 5 to calculate titre value
- Empty the conical flask and wash thoroughly with deionised water
- Refill your burette if necessary . Repeat steps 2-7