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IRINA_888 [86]
2 years ago
6

Which of the following bases is the STRONGEST? The base is followed by its Kb.A. C6H5NH2, 4.0 × 10-10 B. NH3, 1.76 × 10-5 C. CH3

NH2, 4.4 × 10-4 D. (CH3CH2)2NH, 8.6 × 10-4 E. C5H5N, 1.7 × 10-9
Chemistry
1 answer:
Kamila [148]2 years ago
3 0

Answer:

(D) (CH3CH2)2NH

Explanation:

In order to decide which base is strongest we need to calculate its PKb

PKb = -log [Kb]

A large Kb value and small PKb value gives the strongest base

 Compound                   Kb                           PKb      

(A) C6H5NH2 -         4 x 10^-10                      9.349

(B) NH3                     1.76x 10^-5                    4.754

(C) CH3NH2              4.4x 10^-4                     3.357

(D) (CH3CH2)2NH   8.6x 10^-4                     3.066

(E) C5H5N                  1.7x10^-9                      8.77  

Clearly (CH3CH2)2NH is the strongest base.

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A silver cube with an edge length of 2.38 cm and a gold cube with an edge length of 2.79 cm are both heated to 81.9 ∘C and place
never [62]

Answer:

The final temperature of the water when thermal equilibrium is reached is 23.54 ⁰C

Explanation:

<u>Given data;</u>

edge length of silver, a = 2.38 cm = 0.0238 m

edge length of gold, a = 2.79 cm = 0.0279 m

final temperature of silver, t = 81.9 ° C

final temperature of Gold, t = 81.9 ° C

initial temperature of water, t = 19.6 ° C

volume of water, v =  109.5 mL = 0.0001095 m³

<u>Known data:</u>

density gold 19300 kg/m³

density silver 10490 kg/m³

density water 1000 kg/m³

specific heat gold is 129 J/kgC

specific heat silver is 240 J/kgC

specific heat water is 4200 J/kgC

<u>Calculated data</u>

Apply Pythagoras theorem to determine the side of each cube;

Silver cube;

let L be the side of the silver cube

Taking the cross section of the cube (form a right angled triangle), the edge  length forms the <em>hypotenuse side</em>.

L² + L² = 0.0238²

2L² = 0.0238²

L² = 0.0238² / 2

L² = 0.00028322

L = √0.00028322

L = 0.0168

Volume of cube = L³

Volume of the silver cube = (0.0168)³ = 4.742 x 10⁻⁶ m³

Gold cube;

let L be the side of the gold cube

L² + L² = 0.0279²

2L² = 0.0279²

L² = 0.0279² / 2

L² = 0.0003892

L = √0.0003892

L = 0.0197

Volume of cube = L³

Volume of the silver cube = (0.0197)³ = 7.645 x 10⁻⁶ m³

Mass of silver cube;

density = mass / volume

mass = density x volume

mass of silver cube = 10490 (kg/m³) x 4.742 x 10⁻⁶ (m³) = 0.0497 kg

Mass of Gold cube

mass of gold cube = 19300 (kg/m³) x 7.645 x 10⁻⁶ (m³) = 0.148 kg

Mass of water

mass of water = 1000 (kg/m³) x 0.0001095 (m³) = 0.1095 kg

Let the heat gained by cold water be  Q₁

Let the heat lost  by silver cube = Q₂

Let the heat lost  by gold cube = Q₃

Let the final temperature of water = T

Q₁  = 0.1095 kg x 4200 J/kgC x (T–19.6)

Q₂ = 0.0497 kg x 240 J/kgC x (81.9–T)

Q₃ = 0.148 kg x 129 J/kgC x (81.9–T)

At thermal equilibrium;

Q₁ = Q₂ + Q₃

0.1095 x 4200  (T–19.6)  = 0.0497 x 240 x (81.9–T)  + 0.148 x 129 x (81.9–T)

459.9 (T–19.6) = 11.928 (81.9–T) + 19.092(81.9–T)

459.9T - 9014.04 = 976.9032 - 11.928T + 1563.6348 - 19.092T

459.9T + 11.928T + 19.092T = 9014.04  + 976.9032 + 1563.6348

490.92T = 11554.578

T = 11554.578 / 490.92

T = 23.54 ⁰C

Therefore, the final temperature of the water when thermal equilibrium is reached is 23.54 ⁰C

6 0
3 years ago
Priscilla was building a circuit that used copper wires to connect a battery to a light bulb. As she connected the final wire fr
algol [13]

Answer:

The voltage or potential difference

Explanation:

What makes current flow in a circuit is the voltage or the potential difference.

This force is supplied by the battery or the mains electrical circuit.

  • Every circuit requires the voltage to drive current through
  • When a circuit is complete, the battery is able to overcome any resistance by the generating enough voltage which is the force to drive the current through.
7 0
2 years ago
A 29.0-g sample of water at 290. K is mixed with 51.0 g water at 300. K. Calculate the final temperature of the mixture assuming
zubka84 [21]
Let me conduct my research
5 0
2 years ago
Read 2 more answers
NEED HELP QUICKLY!!! How many moles are in each of the following?
oksano4ka [1.4K]

Answer: a. 0.26mol

b. 0.000479mol

c. 1.12mol

Explanation: Please see attachment for explanation

6 0
3 years ago
What are the spectator ions in the equation below? Select all that apply.
Licemer1 [7]

Answer:

H+ and NO3- ions

Explanation:

The Pb²+ ions react with the SO4²‐ ions to form a solid precipitate, i.e. they bond together and undergo a phase change;

On the contrary, the H+ and NO3- ions are aqueous ions before the reaction and the same after the reaction, i.e. they don't change;

Hence, the H+ and NO3- ions are spectator ions

The way to do this type of question is to consider what changes and what doesn't, look at phase changes and oxidation state changes

7 0
2 years ago
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