chapter 13: Acids and Bases Flashcards
what is an acid
- have a sour taste and ability to dissolve metals
what is a base
- bitter taste and feel slippery to the touch
what is the Arrhenius theory
- acids increase the concentration of H+ ions in water
- bases increase the concentration of OH- ions in water
what is a neutralization reaction and what does it produce
solution of an acid and a solution of a base are mixed
- products of the reaction have none of the characteristic properties of the acidic or basic solution
- produces water and a salt
what is a salt
- any ionic compound whose cation comes from a base and anion comes from acid
what is the bronsted lowry theory
HA + B —> A + HB
- acids are proton donors (have a removable acidic proton H+)
- bases are proton acceptors ( lone pair of nonbonding electrons)
what is an amphoteric substance
a substance that can act as either an acid or base
HCL + H20 –> CL = H3O+
NH3 + H2O –> NH4+ + OH- aq)
* water is acting like a base and an acid*
what is a conjugate acid-base pair
acid and a base that differ only in the presence or absence of a proton
- conjugate base: formed by removing a proton from an acid
- conjugate acid: formed by adding a proton to a base
NH3 + H2O = NH4+ OH-
what are the 7 strong acids
- sulfuric acid H2SO4
- Hydrochloric HCL
- Hydrobromic HBr
- Perchloric HCLO4
- Chloric HCLO3
- Hydroiodic HI
- Nitric HNO3
what arrow do strong acids and bases use/ strong electrolytes /
what arrow do weak acids and bases/ weak electrolytes use
- one way arrow not equilibrium bc they dissociate completely
- weak acids and bases use equilibrium arrows bc they don’t dissociate completely
what is a polyprotic acid and monoprotic acid
- monoprotic: 1 ionizable hydrogen
- polyprotic: >1 ionizable hydrogen
- polyprotic is strong and amphoteric conjugate base is weak
what group is in organic acids
- carboxyl group and these acids are weak bc H atoms are not ionizable
what is Ka used for and what is Ka
Ka is the acid dissociation constant
- used to express the extent to which weak acid ionizes
what does a greater Ka mean
stronger the acid
how does polarity affect acid strength
- polarity depends on the strength of the H-Y bond
- stability of the H-Y conjug. base
- more polar means more acidic
how does bond strength affect acid strength
- very strong bonds are less easily dissociated when weaker ones
- strong bonds = strong acid strength
- weak bonds =weak acid strength
what happens to the base when there is a stronger acid
the more stable it is = the less strong
* stronger the acid, the weaker its conjugate base*
- how does acidity increase in the periodic table
- acidity increases from left to right
- top to bottom down a group
what is an oxyacid
OH groups and possible atoms are bound to a central atom
what is the rule of oxyacids
Y-O-H
- electronegativity of Y increases, then will the acidity of the substance
- as electron density is drawn toward the Y, the OH bond becomes weaker and more polar
2. base of the conjug, base is usually an anion
what is the rule for oxyacids that have the same number of O atoms
- H-O-I (weakest weak)
- H-O-Br
- H-O- Cl (strong weak)
- acid strength increases w. the increasing EN of the central atom
what is the rule for oxyacids that have the same central atom
- acid strengh increases as the number of oxygen atoms attached to the central atom increases
example:
HCLO -weakest
HCLO2 - weak
HClO3 - strong acid
HCLO4 - stronger acid
wha tis the most important chemical properties of water related to bronsted and lowry
- autoionization
- act as a base or acid
- in pure water a few molecules act as bases and a few act as acids
what is the Kw expression and what does it equal
Kw = [H3O+][OH]
- @ 25 degrees, Kw for water is 1.0x10^-14
* if you measure one of the conc. you can find the other*
what happens if [H3O] increases
OH must decrease, and it is inverse
what are neutral solutions
equal amounts of H3O and OH
and it equals 1x10^-7
what are acidic solutions
larger [H3O] than [OH]
[H3O] >1x10^-7
[OH] < 1.0x10^07
what is a basic solution
larger [OH] than [H3O]
[OH] > 1x10^-7
[H3O] < 1.0x10^-7
what is the ph and what is the neutral number for pH
- the acidity and bascity of a solution is expressed as pH
- neutral pH = 7
what does a low and high pH range mean and what is the normal range
- low means acidic
- high means basic
- normal range is 0-14
what is the rule of sig figs when using log to calculate pH
of decimal places in the log = the number of sig figs in the OG number
what is the formula for pH and H3O
- Ph = -log(H3O)
H3O = 10^-pH
what is the formula for pOH and OH
pOH = -log[OH]
]OH] = 10^pOH
what is the equation for pH and PoH
ph + PoH = pKw = 14.00
in an aqeuos solution of strong acids what is the source of H+ ions and how do you calculate the pH
- strong acid is the source and to calculate pH
[H3O] = [acid]
how to calculate Ka for weak acids
- use an ice table
- proton transfers for weak acids are rapid
what does percent ionization help us with
show how much of the weak acid has ionized
% ion = [H3O]equilibrium \ [HA] initial x 100
= 10-Ph/ Ha initial x 100
what happens as the concentration of an acid increases
the strength decreases = pH decreases = % ionization also increases
why does % ionization increases as an acid conc. increases
- acid is diuluted by adding water, it shifts the equilibrium to the left ( increase in acid concentration)
- to reach new equilibrium the acid needs to ionnize more
- shift to the right ( H+ concentration)
what are the strong bases
- LiOH
- NaOH
- KOH
- RbOH
- CsOH
- Ca(OH)2
- Sr(OH)2
- Ba(OH)2
what do most weak bases contain
Nitrogen bc the lone pair makes it a great proton acceptor
what is a weak base dissociation constant
Kb
B + H2O —> Hb + OH
what can Kb be used to find
- OH directly and pOH, PH and [H]
- greater value of Kb = stronger base
what is the rule for polyprotic acids
- polyprotic acids ionize in steps
H2SO3 is stronger than HSO3
Ka becomes smaller
when calculating pH and you’re given 2 Ka what Ka should you use
the stronger Ka meaning the one that is the largest
when does percent ionizatoin and pH both increase
as the acid becomes more dilute (less concentrated)
if you are given a concentration like Ca(OH)2
what happens to the concentration
the concentration doubles because there are two hydroxides
what is the factor of Ka value of successive losses of protons
10^3 or greater
from polyprotic acids what can you use to determine the pH
- you can use the first dissociation Ka1 to determine the Ka
what is the relationship between bond strength and acidity
- weaker bond strength = proton more easily donated= increase in the strength of the acid
