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2 years ago

An element that speeds up chemical reactions is called a/an

1 answer:

7 0

I think it is enzymes.Inside our body most of the chemical reactions are speeds up by enzymes.These enzymes decreases the minimum energy that is required for the reaction to happen. ;-]. Actually it works like a catalyst.

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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

2 years ago

What are five objects that are luminous

Nastasia [14]

Some examples:
- the sun
- a flashlight turned on
- a light bulb
- stars
- fireflies
...hope i helped :)

5 0

3 years ago

In the article, Invasion of the Periodical Cicadas, why do scienctists believe that cicadas only reproduce every 13 or 17 years?

frez [133]

Hi, you've asked an incomplete question. However, I assumed you are referring to the article found on the Scientific American website.

Explanation:

Remember, according to that article we are told that scientists notice that these insects have a long nymphal (immature form before becoming adults) stage, one that can last up to 13 to 17 years on the ground before they leave the ground looking for mating partners.

Because it is only after mating occurs at this point that their eggs are laid, that is why scientists believe that cicadas only reproduce every 13 or 17 years.

8 0

2 years ago

A covalent chemical bond is one in which _____. a covalent chemical bond is one in which _____. outer-shell electrons of two ato

PtichkaEL [24]

Answer:

A covalent chemical bond is one in which outer-shell electrons of two atoms are shared so as to satisfactorily fill their respective orbitals.

Explanation:

Covalent bonds are formed between two atoms having their electronegativity difference less than 1.7. In this type of bonding the valence electrons of one atoms forms molecular bond with the valence electrons of another atom. The electrons are mutually shared.

Covalent bond can be non-polar as for example formed between hydrogen and carbon atoms.

Also, covalent bond can be polar in nature as that formed between hydrogen and chlorine atoms because the chlorine atom is more electronegative and hence attracts the electrons more towards itself making density of electrons less on hydrogen atom.

5 0

3 years ago

Read 2 more answers

How do sediments form?

Valentin [98]

Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension

6 0

2 years ago

Read 2 more answers