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3 years ago

Compare the entropy of a firecracker before it is lighted to its entropy after it explodes

1 answer:

3 0

The entropy of a firecracker is much less before it explodes than afterwards.
Entropy is a measure of the degree of disorder in a system.
Before the explosion, everything is packed in a small volume inside a cardboard tube.
After the explosion, the contents have been converted largely to gases and finely divided solids spread over a large volume of the sky.
The latter situation is more disordered, so it has a higher entropy.

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A 275 g sample of a metal requires 10.75 kJ to change its temperature from 21.2 oC to its melting temperature, 327.5 oC. What is

Vlada [557]

Answer:

$c=0.127\ J/g^{\circ} C$

Explanation:

Given that,

Mass of the sample, m = 275 g

It required 10.75 kJ of heat to change its temperature from 21.2 °C to its melting temperature, 327.5 °C.

We need to find the specific heat of the metal. The heat required by a metal sample is given by :

$Q=mc\Delta T$

c is specific heat of the metal

$c=\dfrac{Q}{m\Delta T}\\\\c=\dfrac{10.75\times 10^3\ J}{275\times (327.5 -21.2)}\\\\=0.127\ J/g^{\circ} C$

So, the specific heat of metal is $0.127\ J/g^{\circ} C$ .

4 0

2 years ago

Consider the aldol condensation between dibenzyl ketone and benzil in strong base. Calculate the molar masses of the reactants a

Sati [7]

Answer:

a) 210.3 g/mol

b) 210.2 g/mol

c) 384.5 g/mol

Explanation:

First step we will calculate the molar masses of ; carbon atom, hydrogen atom and oxygen atom in each .

Molar mass of dibenzyl ketone

Molar mass of dibenzyl ketone = ∑ molar masses of atoms in dibenzyl ketone

= carbon( 15 ) = 15 ( 12.0107 ) + oxygen ( 14 ) = 1 ( 15.999 ) + hydrogen(14) =14(1.00784)

= 210.26926 ≈ 210.3 g/mol

Molar mass of benzil

Molar mass of Benzil = ∑ molar masses of atoms in Benzil

= carbon( 14) = 14(12.0107) + oxygen(2) = 2 ( 15.999) + hydrogen(10) =10(1.00784)

= 210.2262 ≈ 210.2 g/mol

Molar mass of 2,3,4,5-tetraphenylcyclopentadienone

Molar mass = ∑ molar masses of atoms

= carbon ( 29) = 29(12.0107) + oxygen (1) = 1( 15.999 ) + hydrogen(20) = 20(1.00784 )

≈ 384.5 g/mol

6 0

3 years ago

Which of the following is a substance that is found between the cell membrane and the nucleus, which primarily consists of water

VladimirAG [237]

The answer is B, cytoplasm

3 0

3 years ago

Read 2 more answers

In the following reaction, how many grams of ammonia (NH3) will react with 27.8 grams of nitric oxide (NO)? 4NH3 + 6NO → 5N2 + 6

Rzqust [24]

4NH₃ + 6NO → 5N₂ + 6H₂O

mol of NO = $\frac{mass of NO}{Molar Mass of NO}$

= $\frac{27.8 g}{30.01 g / mol}$

 = 0.93 mol

Based on the balance equation mole ratio of NH₃ : NO is 4 : 6
= 2 : 3

If mol of NO = 0.93 mol

then mol of NH₃ = $\frac{0.93 mol * 2}{3}$

= 0.62 mol

Mass of ammonia = mol × molar mass

= 0.62 mol × 17.03 g/mol

= 10.54 g

Therefore B is the best answer

3 0

3 years ago

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Design a synthesis of 2-bromo-1-chloro-4-nitrobenzene from benzene or any mono-substituted benzene. Part 1 out of 6 choose the b

Oxana [17]

2-bromo-1-chloro-4-nitrobenzene is being synthesized in following sequence:

Step 1: Chlorination of Benzene:

This is Halogenation reaction of benzene. In this step benzene is reacted with Chlorine gas in the presence of lewis acid (i.e. FeCl₃). This results in the formation of Chlorobenzene as shown in red step below.

Step 2: Nitration of Chlorobenzene:

The chlorine atom on benzene has a ortho para directing effect. Therefore, the nitration of chlorobenzene will yield para nitro chlorobenzene as shown in blue step below.

Step 3: Bromination of 1-chloro-4-nitrobenzene:

In this step bromination is done by reacting bromine in the presence of lewis acid. The chlorine being ortho para directing in nature and nitro group being meta directing in nature will direct the incoming Br⁺ (electrophile) to the desired location. Hence, 2-bromo-1-chloro-4-nitrobenzene is synthesized in good yield.

6 0

3 years ago