Topic 8: Acids and Bases Flashcards
What is the definition of Bronsted Lowry acids and bases?
Acids are a proton donor (or H+ donor), while bases are an H+ acceptor
Acids can be a combination of…
H+ ions and an anion, like HCL
Bases can be a combination of…
OH- and metal cations, like NaOH, or hydrogen with a metal, like NaH
After reacting, acids become…
conjugate bases
After reacting, bases become…
conjugate acids
How do you find the conjugate acid of a reaction?
Add 1 H+ to the base
How do you find the conjugate base of a reaction?
Take away 1 H+ from the acid
What does amphiprotic mean?
A substance that can be either an acid or a base, donating or receiving H+ depending on the other substance, such as H2O
What does amphoteric mean?
A species that can act as an acid or a base, including reactions that do not involve a proton/H+. All amphiprotic species are amphoteric, but not all amphoteric are amphiprotic
What is a neutralization reaction?
An acid and a base reacting to form H2O and a salt.
What are the products of a neutralization reaction? Are they basic/acidic?
H2O and salt. Neither basic nor acidic.
Are neutralization reactions endo or exothermic?
Exothermic
What different types of bases react to form a salt in a neutralization reaction?
Hydroxyl bases, carbonate bases, and metals
How does a hydroxyl base neutralization reaction work? How do you find the salt formula?
acid + hydroxyl base —> salt + H2O. To find the salt, take away the H+ from the acid and the OH- from the base to form H2O. The leftovers form the salt
Finish this hydroxyl neutralization reaction: HCl + NaOH—-> H2O + ___
NaCl
How does a carbonate base neutralization reaction work? How do you find the salt?
acid + carbonate base —> H2O + salt + CO2.
To find the salt, take away H+ from the acid and OH- from the base to form H2O, then account for the CO2. Then the leftovers are the salt.
How does a metal neutralization reaction work? How do you find the salt?
acid + metal —> salt + H2. To find the salt, take away H+ from the acid and OH- from the base, then account for H2. The rest forms the salt.
What are the metals that can react in a neutralization? What metals cannot?
Ca, Mg, and Zn are all reactive. Ag, Cu, Au are not reactive for acid-base reactions.
Is water an acid or a base? If not, what is it? What does that allow water to do?
It is amphoteric and amphiprotic. It can self ionize.
What is the reaction equation for the self-ionization of water?
2 H2O <—> H3O+ + OH-
What represents the constant for the ionization of water?
K subscript w (Kw)
How is Kw calculated? What does it equal?
Kw = [H+] [OH-] = (1 x 10^-7)(1 x 10^-7) = 1 x 10^-14
What does “p” represent in Kw calculations?
Negative logarithm. p= -log
What does pKw equal?
If Kw= 1 x 10^-14, then pKw=14
What does the pH equation look like?
pH= -log[H+]
What does the pOH equation look like?
pOH= - log [OH-]
What does the pH scale represent?
The concentration of H+ in a substance, or how acidic/basic it is.
What ranges of pH are neutral, acidic, or basic?
pH < 7, acidic
pH > 7, basic
pH=7, neutral because [OH-]=[H+]
The concentration of OH- can be found through this equation:
[OH-] = 10 ^(-pOH)
The concentration of H+ can be found through this equation:
[H+]=10^(-pH)
What does it mean for the pH scale to be logarithmic?
Each integer increase changes the concentration by 10. So an increase of 2 is an 100x increase in concentration
Are there units for pH?
No
What are acid base indicators?
pH indicators that are weak acids. They change color to indicate [H+] in a solution. They can be liquid or dye-infused paper strips
What are three different acid base indicators?
Litmus, methyl orange, phenolphthalein
How does a litmus test indicate [H+]?
It turns red in acid and blue in bases
How does methyl orange indicate pH?
It turns red in acid and yellow in base
How does phenolphthalein indicate pH
It is colorless in acid and pink in base
When does the indicator change for an acid-base titration? What indicator should you choose?
It changes at the equivalence point, when the substance is neutral. Choose an indicator that changes color at the steepest point of the titration curce
When does the indicator change for an acid-base titration? What indicator should you choose?
It changes at the equivalence point, when the substance is neutral. Choose an indicator that changes color at the steepest point of the titration curve.
What is acid deposition?
The process by which acid forming pollutants are deposited on earth’s surface
What is the pH of rain? Why? What is the pH of acid rain/deposition?
Rain: pH 5.6 due to dissolved CO2, acid deposition is below 5.6
Does dissolved CO2 alone cause acid rain?
No
What causes acid deposition, what substances are used to lower the pH, what substances form?
occurs when NOx or SOx dissolve in H2O to form HNO2, H2SO4, H2SO3 (weak acids)
What effect does H2SO4 (sulfuric acid) have on the earth?
It corrodes metal/limestone, leaches soil, harms/kills plants
What effect does HNO2 nitrous acid have on the earth?
It corrodes marble/limestone, leaches soil, harms/kills plants
What effect does H2CO3 carbonic acid have on the earth?
It corrodes marble/limestone and acidifies lakes
How does acid rain result?
When SO2 and NOx are transported thru the atmosphere and react with H2O and O2 to form nitric and sulfuric acids, they mix with water and fall to the earth
What does acid deposition do to the earth?
Leaches soul, prevents plant growth, acidifies lakes/rivers, poisons fish, causes asthma
What are methods to prevent/solve acid deposition?
Lower NOx and SOx formation and emission from cars using catalytic converters, using wind/solar energy, liming lakes to neutralize them (adding calcium oxide or calcium hydroxide)
What are characteristics of strong acids?
They fully dissociate in H2O (~100% dissociation), forms strong electrolytes when absorbed in H2O
What are some examples of strong acids?
HCl, H2SO4, HNO3
What are characteristics of weak acids?
Partially dissociates in solution (~5%). Forms weak electrolytes when absorbed in H2O
What are some examples of weak acids?
ethanoic acid (CH3COOH), propanoic acid, carbonic acid, phosphoric acid
At the same concentration, which produces more [H+]: Strong or weak acids?
Strong acids produce more [H+] at the same concentration than weak acids
What is the difference between strong and weak bases
strong bases fully ionize in solution (~100%) while weak bases partially ionize in solution (~5%).
What are some examples of strong bases?
NaOH, KOH, Ba(OH)2, LiOH
What are some examples of weak bases?
NH3 ammonia, ethylamine (CH3CH2NH2)
At the same concentration, do strong or weak bases produce more [OH-]?
Strrong
When dealing with a reaction equation for strong acids/bases, do you use <—> or —> ? Why?
Use —> because it is a one way reaction since it will ionize completely
When dealing with a reaction equation for weak acids/bases, do you use <—> or —> ? Why?
<—> because it will not ionize completely and will exist in equilibrium
Strong acids have ____conjugate bases
weak
Strong bases have ___conjugate acids
weak
What are some experimental techniques to determine the strength of an acid or base?
Conductivity (strong acids/bases are more conductive due to more ions), pH (strong acids have lower pH, strong bases have higher pH), rates of reaction (strong=faster), and strong acids react more vigorously with metals and carbonates
