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chemistry > ammonia > Flashcards

ammonia Flashcards

1
Q

state the observation

burning of ammonia in air

A

a greenish-yellow flame is observed

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2
Q

state the observation

when ammonia is burnt in an atmosphere of excess oxygen

A

ammonia burns with a pale blue flame in the atmosphere of excess oxygen

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3
Q

state the observation

excess of chlorine gas is reacted with ammonia gas

A

a yellow explosive liquid is formed (nitrogen trichloride)

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4
Q

state the observation

ammonia is passed through the copper oxide

A

black copper oxide changes to red copper

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5
Q

state the observation

excess of ammonia is passed through an aqueous solution of lead nitrate

A

a white precipitate is produced which is insoluble even in an excess of ammonia

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6
Q

state the observation

a piece of moist red litmus paper is placed in a gas jar of ammonia

A

it turns blue

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7
Q

state the observation

neutral litmus solution is added to an alkaline solution

A

it turns blue

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8
Q

this gas is used as a reducing agent in reducing copper oxide to copper

A

ammonia

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9
Q

gas produced when excess ammonia reacts with chlorine

A

nitrogen

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10
Q

alkaline gas which gives dense white fumes with HCl

A

ammonia

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11
Q

the gas that can be oxidized to sulphur

A

hydrogen sulphide

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12
Q

an oxidizing agent which does not contain any sulphur

A

chlorine gas

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13
Q

warming ammonium sulphate with sodium hydroxide solution

A

ammonia

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14
Q

drying agent used to dry ammonia

A

CaO

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15
Q

passing dry ammonia over heated copper oxide gives ______

A

copper

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16
Q

ammonia can be obtained by adding water to _______

A

magnesium nitride

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17
Q

ammonium nitrate is used in ___________________

A

preparing explosives

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18
Q

with excess of chlorine what does ammonia form

A

NCl3 [nitrogen trichloride]

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19
Q

why is liquid nitrogen employed in refrigerator

A

because it has a high latent heat of vaporization so it takes high amount of heat from the surroundings resulting in the fall of temperature

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20
Q

why is ammonia soluble in water

A

this is because it is a polar molecule

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21
Q

nesseler’s reagent is an alkaline solution of _____

A

K2HgI4 [Potassium tetraiodomercurate(II)]

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22
Q

what temperature is catalytic oxidation of ammonia carried out at ?????

A

800 degrees celcius

23
Q

where is the nitrogen used in haeber’s process obtained from

A

fractional distillation of air

24
Q

how is ammonia gas collected

A

downward displacement of air

25
Q

why is ammonia used as a cleaning agent

A

ammonia solution emulsifies fat and grease so that they can be removed without leaving any residue

26
Q

ammonia solution is used as a laboratory reagent to identify metal ions

A

aqueous solution of ammonia can precipitate insoluble hydroxide of metals from their salt solutions

hence it is used in the analytical analysis of the salts in the labaratory

27
Q

ammonia is present in sewage water

A

this because ammonia is produced due to bacterial decomposition of urea [NH2CONH2] present in urea

28
Q

solution of ammonia contains hydroxide ions

A

since ammonia turns red litmus solution blue

it reacts with water to form salt and water

29
Q

ammonia cannot be collected over water

A

ammonia is extremely soluble in water and cannot be collected over water

30
Q

though ammonia nitrite readily gives nitrogen on heating,

a mixture of ammonium chloride and sodium nitrite in water is heated to prepare nitrgoen in the labaratory

A

ammonium nitrite cannot be stored even at room therefore nitrogen is obtained by heating ammonium chloride and sodium nitrite

31
Q

magnesium nitride reacts with water to liberate _____ and _________

A

ammonia and magnesium hydroxide

32
Q

what is labaratory bench reagent

A

it is a dilute solution of liquor ammonia

33
Q

why is dry or liquid ammonia neutral to litmus

A

ammonia is a covalent compound therefore in the absence of ions dry or liquid Ammonia has no effect on litmus

34
Q

state the purpose of liquifycing ammonia produced in haeber’s process

A

the ammonia procuced is liquifiedto seperate it from uncombined nitrogen and hydrogen

35
Q

write the equation for Haeber’s process that forms ammonia

A

N2 + 3H2 –> 2NH3 (reversible)

{200-900atm and 450-500 degrees celcius and catalyst Fe and Mo}

36
Q

what test does Nessler’s reagent give with ammonium salts

A

when ammonium compound is added to colourless Nessler’s reagent a brown colour is observed

37
Q

why is acidic drying agent not used for drying ammonia

A

because acidic drying agents such as H2SO4 react with ammonia

38
Q

how does the solubility of ammonia vary with its temperature

A

its solubility decreases with an increase in temperature

39
Q

how will you separate ammonia from uncombined N2 and H2

A

by liquefication

by dissolving in water

40
Q

why is catalyst chamber provided with a heat exchanger

A

this is so that the outgoing ammonia gas and the unreacted gases exchange their heat with the incoming nitrogen and hydrogen

41
Q

which is more dense, ammonia or hydrogen chloride

how is it collected

A

hydrogen chloride is denser than ammonia

upward displacement of air

42
Q

what happens when ammonia and HCl gas react

write the equation

A

NH3 + HCl –> NH4Cl

43
Q

give 2 evidences to show that the solution of ammonia in water contains hydroxide ions

A

i) solution of ammonia is alkaline towards litmus
ii) the solution of ammonia precipitates insoluble metal
hydroxide

44
Q

what is the reactant used in the preapration of ammonia gas

A

Mg3N2 + H2O

45
Q

what is the drying agent used in the preparation of ammonia gas

A

quicklime (Cao)

46
Q

what is the method of collection used in the preparation of ammonia gas

A

downward displacement of air

47
Q

large scale use of ammonia

A

manufacture of nitric acid by ostwalds process

48
Q

what properties of ammonia make it a source of hydrogen

A

–> ammonia can be liquified and transported easily and on decomposition gives hydrogen

–> liquid hydrogen is dangerous to transport in cylinders

49
Q

how is ammonium chloride prepared

A

neutralisation

50
Q

when ammonium chloride is heated what reaction does it undergo

A

thermal dissociation

51
Q

what does heating ammonia chloride with sodium hydroxide produce

A

ammonia

52
Q

why is ammonia nitrate not used in the preparatuon of ammonia

A
  • -> it is explosive in nature

- -> it decomposes giving nitrous oxide and water vapour

53
Q

how do you find out if the jar is full of ammonia gas

A

bring a rod dipped in HCL to the mouth of the jar for which ammonium chloride will be formed

chemistry (14 decks)

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