Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemistry > NH3 [COMPOUND 1] > Flashcards

NH3 [COMPOUND 1] Flashcards

1
Q

What reactants are required for liberation of NH3 gas? [General Question] + condition

A

Ammonium salt and alkali ON DRY HEATING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which are the best reactants for NH3 lab preparation?

A

NH4Cl and Ca(OH)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the name of Ca(OH)2?

A

Slaked lime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the condition for NH3 lab prep.?

A
  1. Dry heating
  2. Reactants are in solid, powdered, ground form.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

State the equation for NH3 lab prep. with best reactants

A

NH4Cl + Ca(OH)2 —> (delta) CaCl2 + NH3 + H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

In what form is the product water in in the lab. prep of NH3?

A

Liquid form.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

If H2O product is a liquid, why do both NH3 and H2O come through the test tube?

A

The continued heat vaporises liquid water product.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is introduced after the dry heating of Ca(OH)2 and NH4Cl?

A

A drying tower.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is a drying tower introduced into lab. prep of NH3.

A
  1. Drying of NH3
  2. Absorption of H2O vapour from NH3
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is used in the drying tower in the lab prep of NH3?

A

CaO- QUICKLIME.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is quicklime used as a drying agent to dry NH3?

A
  1. It is hygroscopic and hence absorbs moisture from NH3
  2. It is basic and hence does not react with final product NH3.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Name the method used for collection of NH3 gas in lab prep

A

Downward displacement of air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What apparatus is used for collecting NH3 product in lab prep?

A

Inverted gas-collecting jar.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why is the method of collection “Downward displacement of air” used for collecting NH3 gas in lab prep?

A

NH3 is less dense than air, and thus can displace it and fill the jar.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Can NH3 be collected by downward displacement of H2O (like Bosch process)?- in lab prep

A

No.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why can’t NH3 be collected by Downward Displacement of H2O in lab prep?

A

NH3 is very highly soluble in water- it will dissolve in water to form NH4OH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How would one test if the gas-collecting jar is FILLED with NH3?

A
  1. When a moist RED litmus paper is brought near the MOUTH of the jar, if it turns blue, jar is filled with NH3 gas.
  2. When a glass rod dipped in conc. HCl is held below the MOUTH of jar, dense white fumes will form if jar is filled with NH3 gas.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

List the apparatus used for lab prep of NH3.

A
  1. Round-Bottom Flask
  2. Drying tower
  3. Inverted gas-collecting jar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 3 main precautions to be taken for lab prep of NH3?

A
  1. Round-Bottom Flask must be in tilted position
  2. Ratio of reactants should be- NH4Cl : Ca(OH)2 = 2 : 3 BY WEIGHT
  3. Reactants must be in solid, powdered ground form.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why must the RB flask be in a tilted position in lab prep?

A

It prevents the trickling of condensed water into the surface of the hot RB flask which can lead to cracking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why must the ratio of reactants in lab prep be 2 : 3 BY WEIGHT?

A

To minimise loss of NH4Cl due to sublimation to gas vapours.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why are the reactants for NH3 lab prep in powdered, ground form?

A

To increase to the surface area of the reactants, which in turn increases the rate and efficiency of the reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why can’t NH4NO3 be used as the ammonium salt for NH3 lab prep?

A
  1. NH4NO3 is EXPLOSIVE on heating
  2. If heated, it decomposes to form LAUGHING GAS [N2O] as a product, which can be an impurity.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Chemical formula of LAUGHING GAS

A

N2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why can't (NH4)2SO4 be used as ammonium salt for NH3 lab prep?
If (NH4)2SO4 is used, then Ca(OH)2 cannot be used as the salt formed is an insoluble salt (precipitation reaction)- and precipitation reaction stop after some time. But Ca(OH)2 needs to be used.
26
Why can't KOH and NaOH be used as the alkali for lab prep of NH3?
1. Much more expensive than Ca(OH)2 2. Corrosive and deliquescent
27
What are the drying agents which cannot be used to dry NH3 gas (in lab prep)?
1. Fused P2O5 2. Conc. H2SO4 3. Anhydrous CaCl2
28
Why can't fused P2O5, conc. H2SO4 and anhydrous CaCl2 be used as drying agents to dry NH3 in lab prep?
They are hygroscopic, but they will combine with the product gas NH3.
29
State the equation of the reaction between P2O5 and NH3.
P2O5 + NH3 + H2O --> (NH4)3PO4 [Ammonium phosphate]
30
State the equation of the reaction between conc. H2SO4 and NH3.
conc. H2SO4 + NH3 --> (NH4)2SO4
31
State the equation of the reaction between anhydrous CaCl2 and NH3?
CaCl2 + NH3 -->CaCl2.8NH3
32
Why is lab prep method 2 seldom used?
Nitrides are very expensive.
33
What is the reaction [general reactants] in lab prep of NH3 method 2?
Metal Nitride + WARM H2O -> NH3 + Metal (OH)x
34
State the equations of lab prep method 2 with 3 metals: Ca, Mg, Al
1. Ca3N2 + WARM H2O -> NH3 + Ca(OH)2 2. Mg3N2 + WARM H2O -> NH3 + Mg (OH)2 3. AlN + WARM H2O -> NH3 + Al(OH)3
35
Pouring warm water on a metal nitride will result in the formation of NH3 and the ____ of the metal
Hydroxide
36
Name the gas formed when warm water is added to a metal nitride
NH3
37
What is the observation upon adding warm water to a metal nitride?
A colourless, pungent gas is liberated that: 1. Turns moist RL- BL 2. Creates dense white fumes upon contact with a glass rod dipped in conc. HCl 3. Nessler's Reagent turns brown upon contact with NH3
38
What is added to a metal nitride to obtain NH3?
WARM H2O.
39
State the precautions to be taken for lab prep method 2
The THISTLE FUNNEL is to be kept submerged in reactants to prevent the gas from escaping through the funnel.
40
State the drying agent used for NH3 lab prep method 2
CaO (QUICKLIME)
41
What is the collection method for NH3 in lab prep 2?
Downward displacement of air
42
Complete the equation: NH4Cl + Ca(OH)2 --> (DRY HEATING)
NH3 + H2O + CaCl2
43
Complete the equation: NH4Cl + NaOH --> DRY HEATING
NH3 + H2O + NaCl
44
Complete the equation: (NH4)2SO4 + NaOH --> DRY HEATING
NH3 + H2O + Na2SO4
45
Name the process by which NH3 is manufactured.
HABER'S PROCESS.
46
What is the equation for Haber's Process?
N2 + H2 <----> NH3 + Δ
47
What are the three characteristics of NH3 manufacture reaction?
1. Catalytic 2. Reversible 3. Exothermic
48
What is the ratio of reactant quantities for Haber's process?
N2 : H2 = 1 : 3 BY VOLUME
49
What are the conditions for Haber's Process? TINKLE PINKLE CACKLE
CATALYST: Fe PROMOTER: Mo TEMPERATURE: 400-500 °C PRESSURE: (VERY HIGH) 200-900 atm
50
State an alternate combination of catalyst and promoter that can be used for Haber's process instead of Fe and Mo
CATALYST: Fe2O3 PROMOTER: - K2O: 1% - Al2O3: 3%
51
State the sources from which reactants for Haber's can be obtained.
N2: LIQUID AIR through FRACTIONAL DISTILLATION. H2: From WATER GAS (By Bosch Process)
52
Other than liquid air through fractional distillation, how else can N2 be obtained?
Thermal decomposition of Ammonium Nitrite [NH4NO2]
53
State the equation thermal decomposition of ammonium nitrite.
NH4NO2-> (DELTA) N2 + H2O
54
State the equation for thermal decomposition of NH4NO3
NH4NO3->(DELTA) N2O + H2O
55
How is the product NH3 separated and recovered from the uncombined reactants during Haber's Process?
METHOD 1: - Liquefaction of NH3 Reason: Only NH3 is easily liquefiable- N2 and H2 are difficult to liquefy. METHOD 2: - Dissolution of NH3 in H2O [collecting NH3 in the form of aqueous NH4OH by passing through H2O] Reason: NH3 is very highly soluble in water, but N2 and H2 are almost insoluble in water.
56
What is the magnitude of heat given out in the exothermic, catalytic, reversible reaction of Haber's process?
22400 Calories
57
What is the taste of NH3?
Bitter
58
How do you calculate the vapour density of a gas?
RMM/2
59
What is a very important precaution to taken during Haber's process?
The Nitrogen-Hydrogen reactant mixture must be free of CO2, H2S, and CO as they may POISON THE CATALYST.
60
[Visualise Clock] What are the 5 PHYSICAL properties of NH3?
1. Gas 2. Pungent and colourless 3. Very highly soluble in water 4. Lighter than air 5. Easily liquefiable
61
What is the benefit of NH3 being easily liquefiable?
It can be used in refrigerants.
62
How many volumes of NH3 will dissolve in one volume of water?
702
63
What is the vapour density of NH3?
8.5 [{14+3}/2]
64
Name the experiment which proves that NH3 is very highly soluble in water.
FOUNTAIN EXPERIMENT
65
Name the experiment which proves that NH3 is very highly soluble in water.
FOUNTAIN EXPERIMENT
66
Describe experimental setup /Apparatus used for FOUNTAIN EXPERIMENT
1. Inverted Dry Round-Bottom Flask filled with dry NH3 2. 2-Hole rubber stopper closing Round-Bottom flask 3. Ink-filler filled with H2O 4. Long jet tube 5. Container filled with RED LITMUS SOL. (in which lower end of jet tube is placed)
67
State procedure for Fountain Experiment
1. Water from filler is introduced into the Round-Bottom Flask
68
What is the observation for the procedure of Fountain Experiment?
The Red Litmus solution from the trough rises up the jet tube and forms a blue fountain inside Round Bottom Flask.
69
What is the reason for the observation for Fountain Experiment?
1. Since almost all NH3 gas dissolves in water, a partial vacuum is created inside RB Flask 2. Since pressure outside is higher, Red Litmus Solution rises up into the RB Flask 3. The fountain is blue because NH3, being basic, changes it from RL sol. to BL. sol.
70
Other than NH3, can the fountain experiment be implemented for any other gas? Which gas?
Yes- HCl gas. HCl is very soluble in water.
71
If HCl is used for fountain experiment, what changes would be made to the NH3 setup?
The trough contain BL sol. instead of RL. sol
72
What are the Two Main Chemical Properties of NH3?
1. Reducing Agent (Gets Oxidised) 2. Basic in nature
73
Can NH3 burn in absence of oxygen?/ Does dry NH3 burn?
No.
74
List the 5 reactions that prove NH3 is a reducing agent.
1. Burning of NH3 in excess O2 2. Catalytic Oxidation of NH3 3. Reaction of nH3 with excess Cl2 4. Reaction of excess NH3 with Cl2 5. Reaction of NH3 with Hot Metal Oxides
75
Which metal oxides does NH3 not react with?
ZnO and above in the Metal Reactivity Series
76
State the equation for the burning of NH3 in excess O2. [43 equation]
NH3 + O2 (excess) ---> N2 + H2O
77
State the equation for the catalytic oxidation of NH3.
NH3+ O2 --Pt. + 800°C--> NO + H2O + Δ
78
State the equation for the reaction of NH3 with excess Cl2.
NH3 + Cl2(excess) ---> NCl3 + HCl
79
State the equation for the reaction of excess NH3 with Cl2.
NH3 (excess) + Cl2 ---> NH4Cl + N2
80
State 2 equations for the reaction of NH3 with Hot Metal Oxides.
1. NH3 + HOT CuO --> Cu + N2+ H2O 2. NH3 + HOT PbO ---> Pb + N2 + H2O
81
What is the general equation for reaction of NH3 with Hot Metal Oxides?
NH3 + HMO ---> Metal + N2 + H2O
82
What is the catalyst used for the Catalytic Oxidation of NH3?
Platinum (Pt.)
83
At the what temperature does Catalytic Oxidation of NH3 take place?
800°C
84
Which reaction of the ones that prove NH3 is a reducing agent is exothermic?
Catalytic Oxidation of NH3.
85
What gas is liberated during the catalytic oxidation of NH3?
NO.
86
What gas is liberated during the reaction between NH3 and a hot metal oxide?
N2
87
What gas is liberated during the reaction between NH3 and excess Cl2?
HCl (hydrogen chloride)
88
What gas is liberated during the burning of NH3 in excess O2?
N2
89
What gas is liberated during the reaction between excess NH3 and Cl2?
N2
90
What is the observation for the catalytic oxidation of NH3? 3 POINTS
1. Round-Bottom Flask is filled with reddish brown gas, which is the combination of the colourless NO and excess O2 2. Exothermic reaction 3. Platinum catalyst continues to glow even after heating is stopped
91
What is the observation for the burning of NH3 in excess O2?
NH3 burns with GREENISH-YELLOW FLAME
92
What is the observation for the reaction of NH3 with hot metal oxides?
1. Black CuO gets reduced to reddish-brown Cu 2. Orange when hot and yellow when cold PbO gets converted to silvery-grey Pb
93
What is the observation for the reaction of excess NH3 with Cl2?
Dense, white sublimable fumes of NH4Cl are formed.
94
What is the observation foe the reaction of NH3 and excess Cl2?
1. Yellow, oily, explosive liquid formed 2. Colourless, odourless gas which produces dense white fumes with a glass rod dipped in NH3 sol. is liberated
95
What do the five reactions where NH3 gets oxidised prove?
This proves that NH3 is a reducing agent.
96
Why is the catalytic oxidation of NH3 so important?
It is the first step of the MANUFACTURE of Nitric Acid by OSTWALD'S PROCESS.
97
Briefly list the three steps of Ostwald's process.
1. NH3 + O2 --Pt. + 800°C--> NO + H2O+Δ 2. NO + O2 --> NO2 3. NO2 + O2 + H2O --> HNO3
98
What is the similarity between Cl2 and HCl?
They both produce dense, white fumes upon contact with NH3.
99
What is the difference between HCl and Cl2?
Cl2, unlike HCl, gives N2 as a product when reacting with NH3.
100
Is NH3 just inherently basic?
No.
101
When does NH3 behave as a basic gas?
In the presence of MOISTURE.
102
When does NH3 behave as a basic gas?
In the presence of MOISTURE.
103
Give an equation to prove the reaction of NH3 with moisture so has to make it basic.
NH3 + H2O --> NH4OH
104
What is NH4OH?
NH4OH is an alkali (a base)
105
What is the action of DRY litmus on DRY NH3 gas?
No change. No effect.
106
When does NH3 turn into a base?
In the presence of moisture.
107
Name an exception to the acid-base neutralisation reaction law.
NH3
108
State the reaction required for moist red litmus to turn to blue.
NH3 + H2O --> NH4OH
109
State 3 reactions to prove NH3 is basic.
1. NH3 + HCl --> NH4Cl 2. NH3 + H2SO4 --> (NH4)2SO4 3. NH3 + HNO3 ---> NH4NO3
110
How do the known three reactions used to prove NH3 is basic PROVE NH3 IS BASIC?
NH3 reacts with acids to form salts.
111
When NH3 reacts with an acid, does water form?
No.
112
How is NH3 gas converted into NH4OH practically?
NH3 should pass through/be dissolved in water.
113
What precautions need to be taken while preparing NH4OH?
1. The end of the delivery tube is connected to an INVERTED FUNNEL. 2. The RIM of the inverted funnel just touches the surface
114
[NH4OH prod.] Why are we attaching an inverted funnel to the delivery tube and hovering on the surface of the water?
NH3 cannot be directly dissolved in water and this is because it leads to BACKSUCTION. BACKSUCTION occurs due to a partial vacuum that is developed in the RB Flask. THIS occurs due to the rate of NH3 formation being slower than the rate of its dissolution in water.
115
Define BACKSUCTION.
Condition wherein water is sucked up through a funnel due to a pressure difference.
116
How do the precautions for the conversion of NH3 to NH4OH help?
1. When backsuction occurs, some H2O rises up the funnel (which has a high SA) due to which an AIRGAP is formed. 2. This AIRGAP equalises the pressure difference and no more H2O can rise up the funnel. 3. More NH3 dissolves int he H2O present in the funnel, making it heaver- heavier NH4OH falls back into the beaker.
117
What are the uses of NH3? REFER MIND MAP.
1. Fertilisers: Urea, NH4NO3, (NH4)2SO4 2. Explosive manufacture: NH4NO3, NCl3 3. H2 source (decomposes to form N2 and H2) 4. Basic gas that is used to manufacture to acid (HNO3) by Ostwald's Process 5. Aqueous solution is used as cleansing agent- EMULSIFIES AND DISSOLVES fats and greases 6. WAS used as a refrigerant, not not-- POISONOUS - then began to use CFCs- O3 dep. (allow UV) - HCFCS- not O3 dep.

Chemistry (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions