A cold pack is snapped, and the chemical reaction causes the pack to feel cold. Which kind of reaction is this

Water ionizes by the equationH2O(l)⇌H+(aq)+OH−(aq)The extent of the reaction is small in pure water and dilute aqueous solutions

tia_tia [17]

Explanation:

$H_2O(l)\rightleftharpoons H^+(aq)+OH^-(aq)$

The value of $K_w$ :

$K_w=[H^+][OH^-]$

a. pOH = 3.51

The sum of pH and pOH is equal to 14.

pH + pOH = 14 (at 25°C)

pH = 14 - 3.51 = 10.49

The pH of the solution is defined as negative logarithm of hydrogen ion concentration in solution.

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

$10.49=-\log[H^+]$

$[H^+]=3.2\times 10^{-11}$

$3.2\times 10^{-11} M$ is the $H^+$ concentration for an aqueous solution with pOH = 3.51 at 25°C.

b.

At a certain temperature, the pH of a neutral solution is 7.56.

Neutral solution means that concentration of hydrogen ion and hydroxide ions are equal.

$[H^+]=[OH^-]$

$7.56=-\log[H^+]$

$[H^+]=2.754\times 10^{-8} M$

The value of $K_w$ at at this temperature:

$K_w=[H^+][OH^-]$

$K_w=[H^+][H^+]$

$K_w=(2.754\times 10^{-8})^2=7.6\times 10^{-16}$

The value of $K_w$ at at this temperature is $7.6\times 10^{-16}$ .

5 0

4 years ago

Name the person who developed a table of elements which revealed

aivan3 [116]

Dimitry Mendeleef

Explanation:

Dimitry Mendeleef developed a table of elements which revealed regularities in elemental properties. He discovered the periodic arrangement of elements in 1869 while playing his game of solitaire.

John Newlands in in 1863 proposed the idea of a repeating octaves of properties of elements.
Dimitry Mendeleef described the periodic table or chart in 1869
The chart was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
In his periodic table, elements were arranged by atomic weights with recurring properties in a periodic manner>

Learn more:

Periodic table brainly.com/question/8543126

#learnwithBrainly

8 0

3 years ago

Identify and label the Brønsted-Lowry acid, its conjugate base, the Brønsted-Lowry base, and its conjugate acid in each of the f

julia-pushkina [17]

Explanation:

As per Brønsted-Lowry concept of acids and bases, chemical species which donate proton are called Brønsted-Lowry acids.

The chemical species which accept proton are called Brønsted-Lowry base.

(a) $HNO_3 + H_2O \rightarrow H_3O^+ + NO_3^-$

$HNO_3$ is Bronsted lowry acid and $NO_3^-$ is its conjugate base.

$H_2O$ is Bronsted lowry base and $H_3O^+$ is its conjugate acid.

(b)

$CN^- + H_2O \rightarrow HCN + OH^-$

$CN^-$ is Bronsted lowry base and HCN is its conjugate acid.

$H_2O$ is Bronsted lowry acid and $OH^-$ is its conjugate base.

(c)

$H_2SO_4 + Cl^- \rightarrow HCl + HSO_4^-$

$H_2SO_4$ is Bronsted lowry acid and $HSO_4^-$ is its conjugate base.

Cl^- is Bronsted lowry base and HCl is its conjugate acid.

(d)

$HSO_4^-+OH^- \rightarrow SO_4^{2-}+H_2O$

$HSO_4^-$ is Bronsted lowry acid and $SO_4^{2-}$ is its conjugate base.

OH^- is Bronsted lowry base and $H_2O$ is its conjugate acid.

(e)

$O_{2-}+H_2O \rightarrow 2OH^-$

$O_{2-}$ is Bronsted lowry base and OH- is its conjugate acid.

$H_2O$ is Bronsted lowry acid and OH- is its conjugate base.

6 0

4 years ago

Which theory describes the motion of and force driving earth’s plates?

swat32

The theory that describes the motion and force driving earth's plates is Plate tectonics

Explanation:

Plate tectonics states that the outer shell of the Earth is divided into plates that glide and move over the mantle which is the surface of the earth.

The mantle is the rocky inner layer above the core of the Earth.

Plate tectonics helped the geologists to explain how continents could move around the planet.

There are 9 major plate tectonics , namely North American, Pacific, Eurasian, Australian, African, Indo - Australian,Indian South American and Antarctic. These plates have been named after the land form found on them.

7 0

3 years ago

True or False-- Siblings (brothers and sisters) may or may not have the same combination of traits.

polet [3.4K]

Answer:

True

Explanation:

Hope it helped. :)

4 0

3 years ago

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