Module Six - Acid/Base Reactions Flashcards
Properties of Acids and Bases Using Brønsted–Lowry Theory Quantitative Analysis (104 cards)
1
Q
what is an oxyanion?
A
inorganic acid that has an oxygen attached to an element (S, N, P, C)
2
Q
what is the name of HNO3?
A
nitric acid
3
Q
what is the name of HCl?
A
hydrochloric acid
4
Q
what is the name of HNO2?
A
nitrous acid
5
Q
what is the name of HCN?
A
hydrocyanic acid
6
Q
what is a binary acid?
A
acid that has a monoatomic ion attached
7
Q
how are binary acids named?
A
- prefix - ‘hydro-‘
- identify the anion
- replace ‘-ide’ with ‘-ic’
e. g. cyanide –> cyanic
8
Q
what is a monoatomic ion?
A
has a charge of +1/-1
e.g. Cl-
9
Q
what is a polyatomic ion?
A
has a charge greater than 1
e.g. SO4(2-)
10
Q
how is an inorganic acid with a polyatomic ion named?
A
- replace polyatomic ion suffix
i.e. ‘-ite’ –> ‘-ous’
i.e. ‘-ate’ –> ‘-ic’ - add ‘acid
e.g. nitrite –> nitrous
nitrate –> nitric
11
Q
what are the common properties of inorganic acids?
A
- sour taste
- conducts electricity
- turns blue litmus to RED
- react with and dissolve active metals with the release of a gas
12
Q
what are the common properties of inorganic bases?
A
- soapy feel (aqueous)
- bitter taste
- conducts electricity
- turns red litmus BLUE
- do not react with carbonates
13
Q
define acid.
A
substance that produced hydrogen ions (H+) in solution
14
Q
what does the H+ ion do when released from an acid in solution?
A
attaches to a water molecule to form hydronium ions (H3O+)
15
Q
define base.
A
e that either contains oxide (O2-) or hydroxide ion (OH-)
16
Q
what is an acid-base reaction called?
A
neutralisation reaction
17
Q
what is the general formula for an acid-base reaction?
A
acid + base –> salt + water
18
Q
what is an example of a base containing the oxide ion?
A
MgO
19
Q
what is an example of a base containing the hydroxide ion?
A
NaOH
20
Q
what is the reaction between HCl and NH3?
A
HCl(aq) + NH3(aq) –> NH4Cl(aq)
21
Q
why is ammonia considered a base?
A
NH3(g) + H2O(l) –> NH4-(aq) +OH-(aq)
22
Q
why is the ammonium ion considered an acid?
A
will react with a base to form salt and water
23
Q
what is the general formula for an acid-carbonate reaction?
A
acid + carbonate –> salt + carbon dioxide + water
24
Q
what is the general formula for an acid-metal reaction?
A
acid + metal –> hydrogen gas + salt
25
what is an example of an acid-metal reaction?
2HCl(aq) + Mg(s) --> MgCl2(aq) +H2(g)
26
what is an example of an acid-carbonate reaction?
2HCl(aq) + CaCO3(s) --> CaCl2(aq) + H2O(l) + CO2(g)
27
what is the general formula for an acid-hydrogen carbonate reaction?
acid _ hydrogen carbonate --> salt + water + carbon dioxide
28
what is an example of an acid-hydrogen carbonate reaction?
HCl(aq) + NaHCO3(s) --> NaCl +H2O(l) +CO2(g)
29
what is the hydrogen carbonate ion?
HCO3-
30
what is the difference between a carbonate ion and a hydrogen carbonate ion?
carbonate : HCO3
| hydrogen carbonate: CO3(2-)
31
what is enthalpy?
measure of the total energy possessed by a substance
32
is energy required to break bonds or form bonds?
break bond
33
is energy released when breaking bonds or forming bonds?
formation of bonds babey
34
is the enthalpy change of an exothermic reaction positive or negative?
negative!!
| ∆H= -ve
35
is the enthalpy change of an endothermic reaction positive or negative?
positive
| ∆H= +ve
36
how can ∆H be calculated using the enthalpy of species in a reaction?
∆H = ∑(enthalpy of products) - ∑(enthalpy of reactants)
37
is the enthalpy of the reactants greater or lower than the products in an exothermic reaction?
greater (energy is lost in reaction)
38
is the enthalpy of the reactants greater or lower than the products in an endothermic reaction?
lower (energy is absorbed)
39
what is the standard enthalpy of neutralisation?
∆H when an aqueous acid and base react to form 1 mole of water
40
what is the specific heat capacity of water?
4.18J/K/g
41
what is the specific heat capacity unit?
J/K/g
42
what is specific heat capacity?
joules of energy required to rise the temperature of the substance by 1˚C
43
how is the quantity of heat (q) calculated?
q = mC∆T
44
how is change in enthalpy (∆H) calculated from quantity of heat (q)?
∆H = (-q)/n
*q must be in KJ*
45
is the reaction between NaOH and HCl endothermic or exothermic?
exothermic
46
can neutralisation be both endothermic and exothermic?
no
47
is neutralisation endothermic or exothermic?
always exothermic
48
what an application of neutralisation in everyday life?
- antacid to assist with heartburn/indigestion
| - toothpaste
49
how does heartburn occur?
- too much HCl in the stomach
| - begins to travel up oesophagus and burn the tissues
50
how do antacids help with heartburn?
neutralises the stomach acids
51
how do antacids relate to neutralisation?
- contains a base [e.g. Mg(OH)2]
| - neutralises extra acid
52
is toothpaste acidic or alkaline?
alkaline
53
why is toothpaste alkaline?
neutralises acids in food we eat to prevent teeth enamel from breaking down
54
how can neutralisation be used in industry?
- neutralisation of soil
| - neutralisation of waste waters
55
why is neutralisation of soil important?
- plants ability to grow is affected
| - some plants can survive in acidic/basic environments though
56
why is neutralisation of waste waters important?
if acidic/alkaline waters enter creeks and rivers, habitats and aquatic life will be hurt
57
who are the five acid and base theorists?
- Lavoisier
- Davy
- Arrhenius
- Brønsted–Lowry
- Lewis
58
what did Antoine Lavoisier (1776) discover ?
- the oxygen theory
| - he demonstrated that non-metal oxides react (dissolved) with water to form acidic solutions
59
what was Laviosier's conclusion from his discovery?
concluded that an acid must contain oxygen
60
what is a limitation of Lavoisier's theory?
not all acids contain oxygen!!
e.g. HCl
He could also not explain why metal oxides were not acidic
61
what did Humphry Davy (1810) discover?
- the hydrogen theory
- he observed that when HCl gas and H2S gas dissolved in water they produced acidic solutions. These molecules had no
- recognised that the key element in acids was hydrogen
- metals with oxygens were bases
- acid + base --> salt + water
62
what was Davy's theory?
acids are substances which contain replaceable hydrogens which could be displaced by metals in solution
63
what are the limitations to Davy's theory?
- not all substances that contain hydrogen are acids
- some acid-base reactions don't produce salt and water
- no distinction between weak and strong acids
64
what is Arrhenius' definition of an acid?
substances that dissociate and ionise in water (produce H+)
65
what is Arrhenius' definition of a base?
substances that dissociate in water to produce hydroxide ions (OH-)
66
what are the limitations to Arrhenius' theory?
- could not explain why ammonia (NH3) was a base
| - does not apply to non-aqueous solvents
67
what is an example of Arrhenius' acid-base model?
HCl dissociates in water to produce H+ and Cl- ions
68
what is Brønsted–Lowry's definition of an acid?
acids are proton donors
69
what is Brønsted–Lowry's definition of a base?
bases are proton acceptors
70
what limitation of Arrhenius did Brønsted–Lowry's theory work out?
able to explain why NH3 was a base
71
what is an example of a Brønsted–Lowry acid?
HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq)
| - HCl accepts a proton!
72
what is an example of a Brønsted–Lowry base?
NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq)
| - NH3 accepts a proton!
73
how is a conjugate base formed?
when an acid loses a proton
74
how is a conjugate acid formed?
when a base gains a proton
75
how many protons do conjugate acid-base pairs differ from?
1
76
will a strong acid produce a strong or weak conjugate base?
weak
77
will a weak acid produce a strong or weak conjugate base?
strong
78
will a strong base produce a strong or weak conjugate acid?
weak
79
will a strong acid produce a strong or weak conjugate base?
strong
80
what is the conjugate base of HCl?
Cl-
81
what is the conjugate acid of NH3?
NH4+
82
what are the limitations of Brønsted–Lowry's theory?
- solvent must be present (allows transfer of protons)
- unable to explain reactions between acidic oxides and basic oxides w/o a solvent
- unable to explain reaction between non-protonic (no H+) solvents
83
what are examples of acidic oxides?
CO2, SO2, SO3
84
what are examples of basic oxides?
CaO, BaO, MgO
85
what is an example of non-protonic solvents?
AlCl3
86
what is Lewis' definition of an acid?
an acid is an electron pair acceptor
87
what is Lewis' definition of a base?
a base is an electron pair donator
88
what are the limitations of Lewis' theory?
- all acid-base reactions do not involve coordinate bond formation (e.g. HCl, H2SO4)
- does not explain strength of acids and bases
89
what is the pH scale used for?
to quantitatively measure the acidity of a solution
90
what does pH stand for?
hydrogen power
91
how is the pH value calculated from the [H+]?
pH = -log[H+]
92
how is [H+] calculated from the pH value?
10^-n
| *n is the pH value*
93
how is concentration different from strength in acids and bases?
concentration : amount of solute in a solution (concentrated - diluted)
strength : degree of ionisation (strong - weak)
94
what makes an acid/base strong?
ability to ionise completely
95
what makes an acid/base concentrated?
less solute in solution
96
what are examples of a strong acid?
HCl, H2SO4
97
what are examples of a weak acid?
CH3COOH. H2CO3
98
what are examples of a strong base?
NaOH, KOH
99
what are examples of a weak base?
NH3, CH3NH2
100
what is a polyprotic acid?
acids that can give up more than one proton!
101
What is the pH range of methyl orange?
pH range between 3.2 (red) and 4.4 (yellow)
102
What is the pH range of bromothymol blue?
pH range from 6.0 (yellow) to 7.6 (blue)
103
What is the pH range of phenolphthalein?
8.2 (colourless) to 10 (pink)
104
How is the acidity of soil measured?
White barium sulfate is added to a wet soil sample in a petri dish. When the universal indicator is added to the white later the colour change reveals the pH of the soil water.
