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3 years ago

Freeeeeeeeeeee Poinnnnnnntttsss

Chemistry

2 answers:

Marina CMI [18]3 years ago

8 0

Hellllooooo how are you

leva [86]3 years ago

5 0

Answer:

thanks

Explanation:

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A system does 591 kJ of work and loses 256 kJ of heat to the surroundings.

Mars2501 [29]

Answer:

-847kj

Explanation:

Delta E= -256+-591

5 0

3 years ago

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:

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.

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

What does ambitious mean?

Kobotan [32]

Answer:

Determination to succeed.

Explanation:

3 0

2 years ago

Read 2 more answers

Name at least three types associated with the microwave

Bond [772]

Hi , if you are asking for the types of energy , here's your answer:

1. Radiative energy , because the microwave is releasing radiation.
2.Light energy , because there is light inside the microwave.
3.electronic energy , because the microwave is using electricity.

8 0

3 years ago

How many moles of liquid water must freeze to remove 100 kJ of heat? (ΔHf = –334 J/ g.

Juliette [100K]

First figure out how many grams must freeze and then convert the grams to moles.
Hf = -334 J/g. Convert this to KJ/g by dividing by 1000. (There are 1000 Joules in a kJ). 
Hf = -334 J/g ÷ 1000 J/kj = -0.334 kJ/g 
Now, divide 100 kJ by -0.334 kJ/g (see how the units are lining up?) 
100 kJ ÷ -0.334 kJ/g = 299 g 
Now convert this to moles by dividing by the molecular weight of water (18.0g/mole). 
299 ÷ 18.0 = 16.6 moles

5 0

3 years ago