Acids and bases, stoichiometry and moles test Flashcards
What does it mean when we say this chemical is classed as an acid?
Acids are compounds or ions that donate protons, whereas bases are compounds or ions that accept protons.
What is a hydronium ion?
Hydronoium is a cation, formed by water plus an extra hydrogen. H30
Monoprotic, vs diprotic vs triprotic.
Monoprotic acids can only release one proton or hydrogen ion per molecule. Diprotic can release up to 2, triprotic can release up to 3.
What is ionisation?
Ionisation is the process by which an atom or molecule gains or loses electrons, resulting in the formation of an ion.
What is the difference between a strong acid and a weak acid?
Strong acids ionise completely - 100% ionisation. Weak acids ionise partially - less than 10% ionisation.
What do acids do in water?
Ionise
What happens to electrical current if an acid is added to water.
Increases electrical current due to the transfer and movement of the H+ ions.
Examples of strong acids:
Sulfuric Acid, hydrochloric acid and nitric acid.
What is the arrow for complete ionisation.
Single arrow
What is the arrows for partial ionisation.
Two arrows same length.
What is the arrows for minimal ionisation.
Two arrows, one shorter than the other.
pH value of strong acids vs weak acids.
Strong acids ph roughly 1, whereas weak acids pH 2-6.
What will happen when a strong acid is mixed with a weak base?
The strong acid will almost completely ionise in water and disassociate the hydrogen ions. However because it is a weak base not all of those will be accepted by the base. There will be leftover H+ ions. The reaction will not fully neutralise.
Two solutions, one of hydrochloric acid and one of acetic acid, both have a pH of 4.
Explain how can this be correct, even though one is a weak acid and one is a strong acid?
HCl is a strong acid completely ionises, very little acetic acid ionises in water. Therefore to achieve the same pH a much higher concentration of acetic acid is required. And a lower concentration of HCl to compensate for the differences in ionisation.
What is nitric acid?
HNO3
What is acetic acid?
CH3COOH
What is bicarbonate?
Hydrogen carbonate. HCO3
What is carbonic acid?
H2CO3 - can convert to water and carbon dioxide.
What is an amphiprotic substance?
An amphiprotic substance is a proton-bearing molecule that is capable of donating its proton as well as accepting an additional proton.
Equation for why rainwater is slightly acidic?
H20 + CO2 - H2CO3 (Carbonic acid)
Why would you swirl the acid during a titration?
To evenly distribute the acid/alkali.
What colour is phenolphalein in acidic solutions?
Colourless, it is pink in alkaline solutions.
What is the natural pH of rainwater? Why?
The presence of this carbonic acid means that the pH of rainwater is naturally around pH 5.6.
What is the definition of acid rain?
Acid rain is defined as rainwater that has a pH less than 5.6. The production of acid rain occurs when acids (stronger than carbonic) form as a result of sulphur and nitrogen in the atmosphere.
Name two oxides that are produced in the combustion of fossil fuels
SO2 + N02 (sulfur dioxide and nitrogen dioxide)
What are some damaging effects of acid rain?
Damage to plants, acidification of ocean and water ways, damage to fish gills. damage to buildings, particularly limestone and marble.
Definition of molar mass
is the mass in grams of 1 mole of a substance
In a galvanic cell, how do you tell which half cell is the anode, and which is the cathode?
The more reactive of the 2 metals is the anode, the negative electrode. The less rective of the 2 metals is called the cathode, the positive electrode.
In the galvanic cell, which half cells do oxidation and reduction take place.
Oxidation always takes place at the anode, reduction at the cathode.
What is the purpose of the salt bridge in a galvanic cell?
The purpose of the salt bridge is to keep the solutions electrically neutral and allow the free flow of ions from one cell to another. Without the salt bridge, positive and negative charges will build up around the electrodes causing the reaction to stop.
What are the indicators of an oxidation reaction?
Loosing electrons, gaining oxygen. Loosing hydrogen. Increase in oxidation number. It is called an oxidation number, therefore an increase.
What are the indicators of a reduction reaction?
Gaining electrons, loosing oxygen. Gaining hydrogen. Decrease in oxygdation numbers, because of the gained electrons.
What is an oxidant?
The one that is being reduced. An oxidant causes another substance to be oxidised.
What is a reductant?
A reductant is the one being oxidised. It causes another substance to be reduced.
Define a galvanic cell? What are it’s components and how does the system work?
A galvanic cell is a system that.
-consists of electrodes (metal or carbon rods)
That dip into an electrolyte
In which a chemical reaction happens
-That generates an electrical current.
Which directions do the electrons travel along the wire in a galvanic cell?
From the anode to the cathode.
