Acids and Bases Flashcards

1
Q

What is a Bronsted-Lowry Acid?

A

A proton donor

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2
Q

What is a Bronsted-Lowry Base?

A

A proton acceptor

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3
Q

What does an Acid + Hydroxide produce?

A

Salt and water
e.g. CH3COOH(aq) + NaOH(aq)  NaCH4COO(aq) + H2O(l)

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4
Q

What does a metal oxide and acid produce?

A

Salt and water

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5
Q

What do acids and ammonia react to produce?

A

A salt
e.g. HCl(aq) + NH3 (aq)  NH4Cl(aq)

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6
Q

What do acids and carbonates produce?

A

Salt, water, Carbon dioxide

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7
Q

What do acids and hydrogen carbonates produce?

A

Salt, water, Carbon dioxide

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8
Q

State the color of Universal indicator at pH: 0, 4, 7, 10, 14

A

0 - red
4 - orange
7 - green
10 - blue
14 - purple

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9
Q

What does it mean if a substance is strong?

A

completely dissociated into ions

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10
Q

What does it mean if a substance is concentrated?

A

a high number of moles of solute per litre
(dm3 ) of solution

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11
Q

What does it mean if a substance is corrosive?

A

Chemically reactive

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12
Q

What happens when a solution of pH 1 is diluted 10 times

A

It becomes pH 2

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13
Q

Formula for pH

A

-log(base 10) [ H+ ion conc.]

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14
Q

Formula for [H+]

A

10^(-pH)

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15
Q

What is [H+] x [OH-]

A

1 x 10^(-14)

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16
Q

How does sulphuric oxide get into the atmosphere and what is its effect?

A

Sulfur dioxide occurs naturally
from volcanoes. It is produced industrially rom the combustion of sulfur-containing fossil fuels and the smelting of sulfde ores.
S(s) + O2 (g) -> SO2 (g)
In the presence ofsunlight sulfur dioxide is oxidized to sulfur trioxide.
SO2 (g) + 1/2O2 (g) ->SO3 (g)
The oxides can react with water in the air to form sulfurous acid and sulfuric acid:
SO2 (g) + H2O(l) -> H2SO3 (aq)
and
SO2 (g) + H2O(l) -> H2SO4 (aq

17
Q

How do Nitrogen oxides get into the atmosphere and what is the effect?

A

Nitrogen oxides occur naturally from electrical storms and bacterial action. Nitrogen monoxide is produced in the internal combustion engine and in jet engines.
N2 (g) + O2 (g) -> 2NO(g)
Oxidation to nitrogen dioxide occurs in the air.
2NO(g) + Ow (g) -> 2NO2 (g)
The nitrogen dioxide then reacts with water to form nitric acid and nitrous acid:
2NO2 (g) + H2O(l) -> HNO3 (aq) + HNO2 (aq)
or is oxidized directly to nitric acid by oxygen in the presence of water:
4NO2(g) + O2 (g) + 2H2O(l)  4HNO3 (aq)

18
Q

What is acid deposition?

A

Pure rainwater is naturally acidic with a pH o 5.65 due to the presence o dissolved carbon dioxide. Acid rain since acid rain is defned as rain with a pH less than 5.6. It is the oxides o sulur and nitrogen present in the atmosphere which are responsible or acid deposition

19
Q

How do we counteact acid deposition?

A
  1. Lower the amounts o NO and SO ormed, e.g. by improved engine design, the use o catalytic converters, and removing xx
    sulur beore, during, and ater combustion o sulur-containing uels.

2, Liming o lakes  adding calcium oxide or calcium hydroxide (lime) neutralizes the acidity, increases the amount o calcium ions and precipitates aluminium rom solution. This has been shown to be eective in many, but not all, lakes where it has been tried.

20
Q

What is a lewis acid?

A

Substances which accept a pair of electrons

21
Q

What is a lewis base?

A

Substances which donate a pair of electrons.

22
Q

How does the Kw value change with increasing temperature?

A

Kw increase with temp.

23
Q

Formula for pOH

A

-log(base 10) [OH- conc]

24
Q

Formula for pKw

A

-log(base 10) [Kw]

pKw = pH + pOH = 14

pKa + pKb = pKw

25
Q

What is Ka? and give its formula.

A

Ka is the dissociation constant of a weak acid

HA(aq) –> H+ (aq) + A- (aq)

Ka = ( [H+] x [ A-] ) / [HA]

26
Q

Why are the salts from a weak acid + strong base or strong acid + weak base slightly acidic / alkaline when dissoolved?

A

Salts made rom a weak acid and a strong base, such as sodium ethanoate, are alkaline
in solution. This is because the ethanoate ions will combine with hydrogen
ions rom water to orm mainly undissociated ethanoic acid, leaving excess hydroxide ions in solution.

27
Q

What is a buffer solution

A

A buffer solution resists changes in pH when small amounts o acid or alkali are added to it

28
Q

How are acidic buffers made? and how they work when an acod or alkali are added to the solution?

A

An acidic buffer solution can be made by mixing a weak acid together with the salt o that acid and a strong base. An example is a solution o ethanoic acid and sodium ethanoate. The weak acid is only slightly dissociated in solution, but the salt is ully dissociated into its ions, so the concentration o ethanoate ions is high

NaCH3COO(aq) –>Na+ (aq) + CH3COO- (aq)
CH3COOH(aq) <–> CH3COO- (aq) + H+ (aq)

 an acid is added the extra H+ ions coming rom the acid are removed as they combine with ethanoate ions to orm undissociated ethanoic acid, so the concentration o H+ ions remains unaltered.

I an alkali is added the hydroxide ions rom the alkali are removed by their reaction with the undissociated acid to orm water, so again the H+ ion concentration stays constant.

29
Q

When does pKa = pH on a titration curve?

A

When half the required volume to get to the inflexion point is reached

30
Q

pH range of Methyl orange

A

3.1-4.4

31
Q

pH range of Phenolphthalein

A

8.3-10.0

32
Q

How does pKa change with increasing acid strength?

A

pKa is decreasing at higher pH

33
Q

How does Ka change with increasing acid strength?

A

Ka increases with higher pH

34
Q

State the equation for a general acidic indicator

A

HIn (color a) —> H+ + ln- (color b)

35
Q

What is a conjugate base?

A

The conjugate base of an acid is the species remaining after the acid has lost a proton

36
Q

What is the color range of an Indicator in Acidic conditions

A

The colour change can be considered to take place over a range of pKa ± 1.