Nine and ten im stuck on them

Aspirin (acetylsalicylic acid, C9H8O4) is a weak monoprotic acid. To determine its acid-dissociation constant, a student dissolv

Triss [41]

Answer:

1. $3.57\times 10^{-4}$ was the $K_a$ value calculated by the student.

2. $5.93\times 10^{-4}$ was the $K_b$ of ethylamine value calculated by the student.

Explanation:

1.

The $pH$ value of Aspirin solution = 2.62

$pH=-\log[H^+]$

$[H^+]=10^{-2.62}=0.00240 M$

Moles of s asprin = $\frac{2.00 g}{180 g/mol}=0.01111 mol$

Volume of the solution = 0.600 L

The initial concentration of Aspirin = c = $\frac{0.01111 mol}{0.600 L}=0.0185 M$

$HAs\rightleftharpoons As^-+H^+$

initially

c 0 0

At equilibrium

(c-x) x x

The expression of dissociation constant :

$K_a=\frac{[As^-][H^+]}{[HAs]}$ :

$K_a=\frac{x\times x }{(c-x)}$

$=\frac{0.00240 M\times 0.00240 M}{(0.0185-0.00240 )}$

$K_a=3.57\times 10^{-4}$

$3.57\times 10^{-4}$ was the $K_a$ value calculated by the student.

2.

The $pH$ value of ethylamine = 11.87

$pH+pOH=14$

$pOH=14-11.87=2.13$

$pOH=-\log[OH^-]$

$[OH^-]=10^{-2.13}=0.00741 M$

The initial concentration of ethylamine = c = 0.100 M

$C_2H_5NH_2+H_2O\rightleftharpoons C_2H_5NH_3^{+}+OH^-$

initially

c 0 0

At equilibrium

(c-x) x x

The expression of dissociation constant :

$K_b=\frac{[C_2H_5NH_3^{+}][OH^-]}{[C_2H_5NH_2]}$ :

$K_b=\frac{x\times x}{(c-x)}$

$=\frac{0.00741\times 0.00741}{(0.100-0.00741)}$

$K_b=5.93\times 10^{-4}$

$5.93\times 10^{-4}$ was the $K_b$ of ethylamine value calculated by the student.

3 0

3 years ago

To vaporize/condense a substance, does the substance have to absorb or release heat?

lilavasa [31]

Answer: it would release heat because the thermal energy it absorbed to become a gas. so it would release heat. hope this helps :)

Explanation:

8 0

3 years ago

DIRECTIONS: Use the Word Bank to answer the questions below. For questions 2 and 3 circle the correct choice.

Angelina_Jolie [31]

Explanation:

1. Electrons surround the nucleus in defined regions called orbits.

2. The shells further away from the nucleus are larger and can hold more electrons.

3. The shells closer to the nucleus are smaller and can hold less electrons.

4. The closest shell (closest to the nucleus) can hold a maximum of two electrons.

5. Once the first shell is full, the second shell begins to fill. It can hold a maximum of eight electrons.

6. Once the second shell is full, the third shell begins to fill.

7. Once the third shell contains Eighteen electrons, the fourth shell begins to fill.

8. The arrangement of electrons in shells around the nucleus is referred to as an atom's electronic configuration.

8 0

3 years ago

When hydrated copper(II) sulfate crystals are heated, anhydrous copper(II) sulfate forms. A mass of 12.5 g of hydrated copper(II

pychu [463]

The formula of hydrated copper(II) sulfate is CuSO4.10H2O

<h3>What is the formula of the hydrated copper (ii) sulfate salt?</h3>

The formula of the hydrated copper (ii) sulfate is determined as follows:

Mass of hydrated salt = 12.5 g

Mass of anhydrous salt = 8.0 g

Mass of water = 12.5 - 8 = 4.5 g

mole ratio of water and anhydrous salt is;

4.5/18 : 8.0/159.5

0.562 : 0.05

10 : 1

Water of crystallization (n) = 10.

Therefore, the formula of hydrated copper(II) sulfate is CuSO4.10H2O

Learn more about water of crystallization at: brainly.com/question/26146814

#SPJ1

7 0

2 years ago

One scientific investigation may result in

Paladinen [302]

Answer:

a new discover a new theory

4 0

2 years ago

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