Hydrogen Test

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Hydrogen Test - 38

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Weekly Quiz Competition

Question 1
1 / -0

Consider a lab in which a hydrate is heated to determine the waters of hydration.
Which error would increase the calculated number of waters of hydration?

A
Touching crucible and leaving fingerprints after heating, but before the final weighing.

B
Incomplete heating, not heating until a constant mass is obtained.

C
The hydrate sample was contaminated with another ionic substance that has a melting point such higher than $$100$$ degrees Celsius.

D
While transferring the crucible containing the anhydrous material to the balance for massing, the crucible tongs touched the product, leaving some of the solid product on the tongs.

Solution

Do not touch vessels, beaker and crucible, with fingers. Oils from the skin can be
left on the vessels and introduce error into the data.It increase the calculated number of waters of hydration.
Question 2
1 / -0

Which of the following particle diagrams BEST represents the structure of ice, $$H_{2}O(s)$$?

A

B

C

D

Solution

The atomic structure of a water (or dihydrogen monoxide) molecule consists of two hydrogens $$(H)$$ atoms joined to one oxygen $$(O)$$ atom. The unique way in which the hydrogen atoms are attached to the oxygen atom causes one side of the molecule to have a negative charge and the area in the opposite direction to have a positive charge. The resulting polarity of charge causes molecules of water to be attracted to each other forming strong molecular bonds.
Question 3
1 / -0

Which laboratory procedure will produce the data necessary to determine the waters of hydration in a hydrate?

A
Reacting the hydrate with a base to neutralize and produce water. The amount and concentration of base used should be recorded as well as the final mass of water produced.

B
Reacting the hydrate with a acid to neutralize and produce water. The amount and concentration of base used should be recorded as well as the final mass of water produced.

C
Recording the amount of water in mL added to the anhydrous material until it is a saturated hydrate.

D
Recording the mass of the hydrate before heating and then recording the mass of the anhydrous salt after heating, until constant mass is obtained.

Solution

Some compounds contain larger amounts of water that is chemically bound to the crystal. This water is called water of hydration and is usually bound to the cations in the salt. The water molecules in a hydrate are removed easily by heating to a temperature above the boiling point of water.
Question 4
1 / -0

Which of the following hydride is 'electron-precise' type?

A
$$HF$$

B
$$H_2O$$

C
$$SiH_4$$

D
$$PH_3$$

Solution

Hydrides of carbon family known as electron Precise.
Question 5
1 / -0

Which of the following will produce hydrogen on decomposition by metals like $$Na,K,Ca$$?

A
Boiling water

B
Steam

C
Cold water

D
All of the above

Solution

$$Na,K,Ca$$ lie at the top of the electrochemical series and are very easily oxidised which makes it a very strong reducing agent.As a result,it can reduce all the three,i.e,boiling water,steam,cold water.
Question 6
1 / -0

Which one of the following is not an industrial method of preparation of hydrogen?

A
Electrolysis of brine

B
Electrolysis of acidified water

C
Wurtz reaction

D
Boschs process or Lanes process

Solution

The Wurtz reaction, named after Charles-Adolphe Wurtz, is a coupling reaction in organic chemistry, organometallic chemistry and recently inorganic main group polymers, whereby two alkyl halides are reacted with sodium to form a new alkane:

$$2R–X+2{ Na }^{ + }\longrightarrow R–R+2{ Na }^{ + }+{ X }^{ - }$$
Question 7
1 / -0

The carbon dioxide produced in water gas shift reaction is removed by scrubbing with :

A
sodium hydroxide solution

B
sodium arsenite solution

C
sodium chloride solution

D
water

Solution

In chemistry, an arsenite is a chemical compound containing an arsenic oxoanion where arsenic has oxidation state +3. Sodium arsenite is used in the water gas shift reaction to remove carbon dioxide.
Question 8
1 / -0

Zinc react with aqueous sodium hydroxide to form dihydrogen and __________.

A
zinc oxide

B
sodium zincate

C
zinc hydroxide

D
sodium precipitate

Solution

Zinc will react with Sodium Hydroxide to from Sodium Zincate. In this reaction Zinc will not displace sodium from sodium hydroxide, but will displace Hydrogen as shown below:
$$2NaOH+Zn\longrightarrow { Na }_{ 2 }Zn{ O }_{ 2 }+{ H }_{ 2 }$$

This reaction is accompanied by evolution of Hydrogen gas.
Question 9
1 / -0

High purity (>99.95%) dihydrogen is obtained by electrolyzing warm aqueous ________ hydroxide solution between nickel electrodes.

A
magnesium

B
barium

C
calcium

D
sodium

Solution

Pure hydrogen gas can be prepared by the electrolysis of warm solution of barium hydroxide using platinum or nickel electrodes. As water does not conduct electricity very well, so it is usual to electrolyse aqueous solution of barium hydroxide. The gases produced in the anode and cathode compartment must be kept separate. Following reactions occur at anode and cathode.
Question 10
1 / -0

On electrolysis of NaH, hydrogen is liberated at:

A
anode

B
cathode

C
inert electrode

D
none of these

Solution

Sodium hydride is an ionic compound which decomposes below its melting point, so it would be extremely difficult to obtain molten sodium hydride in the first place.

However, if you were able to somehow melt some sodium hydride, its electrolysis would produce liquid sodium metal at the cathode and hydrogen gas at the anode;-

Cathode reaction:

$$2{ Na }^{ + }+2{ e }^{ - }\longrightarrow 2{ Na }_{ (l) }$$

Anode reaction:

$$2H\longrightarrow { H }_{ 2(g) }+2{ e }^{ - }$$

The overall reaction is:

$$2Na{ H }_{ (l) }\longrightarrow 2{ Na }_{ (l) }+{ H }_{ 2(g) }$$

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Hydrogen Test - 38

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Hydrogen Test - 38

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Question 1

Touching crucible and leaving fingerprints after heating, but before the final weighing.

Incomplete heating, not heating until a constant mass is obtained.

The hydrate sample was contaminated with another ionic substance that has a melting point such higher than $$100$$ degrees Celsius.

While transferring the crucible containing the anhydrous material to the balance for massing, the crucible tongs touched the product, leaving some of the solid product on the tongs.

Solution

Question 2

Solution

Question 3

Reacting the hydrate with a base to neutralize and produce water. The amount and concentration of base used should be recorded as well as the final mass of water produced.

Reacting the hydrate with a acid to neutralize and produce water. The amount and concentration of base used should be recorded as well as the final mass of water produced.

Recording the amount of water in mL added to the anhydrous material until it is a saturated hydrate.

Recording the mass of the hydrate before heating and then recording the mass of the anhydrous salt after heating, until constant mass is obtained.

Solution

Question 4

$$HF$$

$$H_2O$$

$$SiH_4$$

$$PH_3$$

Solution

Question 5

Boiling water

Steam

Cold water

All of the above

Solution

Question 6

Electrolysis of brine

Electrolysis of acidified water

Wurtz reaction

Boschs process or Lanes process

Solution

Question 7

sodium hydroxide solution

sodium arsenite solution

sodium chloride solution

water

Solution

Question 8

zinc oxide

sodium zincate

zinc hydroxide

sodium precipitate

Solution

Question 9

magnesium

barium

calcium

sodium

Solution

Question 10

anode

cathode

inert electrode

none of these

Solution

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