What are half-reactions?

EXTRA POINTSSS 1. A solution at 25 degrees Celsius is 1.0 × 10–5 M H3O+. What is the concentration of OH– in this solution?

AlekseyPX

Answer:

Concentration of OH⁻:

1.0 × 10⁻⁹ M.

Explanation:

The following equilibrium goes on in aqueous solutions:

$\text{H}_2\text{O}\;(l)\rightleftharpoons \text{H}^{+}\;(aq) + \text{OH}^{-}\;(aq)$ .

The equilibrium constant for this reaction is called the self-ionization constant of water:

$K_w = [\text{H}^{+}]\cdot[\text{OH}^{-}]$ .

Note that water isn't part of this constant.

The value of $K_w$ at 25 °C is $10^{-14}$ . How to memorize this value?

The pH of pure water at 25 °C is 7.
$[\text{H}^{+}] = 10^{-\text{pH}} = 10^{-7}\;\text{mol}\cdot\text{dm}^{-3}$
However, $[\text{OH}^{-}] = [\text{H}^{+}]=10^{-7}\;\text{mol}\cdot\text{dm}^{-3}$ for pure water.
As a result, $K_w = [\text{H}^{+}] \cdot[\text{OH}^{-}] = (10^{-7})^{2} = 10^{-14}$ at 25 °C.

Back to this question. $[\text{H}^{+}]$ is given. 25 °C implies that $K_w = 10^{-14}$ . As a result,

$\displaystyle [\text{OH}^{-}] = \frac{K_w}{[\text{H}^{+}]} = \frac{10^{-14}}{1.0\times 10^{-5}} = 10^{-9} \;\text{mol}\cdot\text{dm}^{-3}$ .

8 0

4 years ago

Individual solute particles are broken apart from the solid by these particles. * a Solution b Insoluble c Solvent d Compounds

Maru [420]

Answer:

Individual solute particles are broken apart from the solid by the;

c. Solvent

Explanation:

A solution is the homogeneous mixture that is made up of two or more substances formed by dissolving a substance which can be a solid, liquid or gas in another substance known as the solvent which normally the larger part of the fraction of the solution than the solute and can also be a solid, liquid or a gas

In a solution the solvent particles serves to brake of and disperser parts of a solid solute to form a more or less homogeneous mixture

Therefore, the solute particles are broken by the <u>solvent</u> particles in a solution

7 0

3 years ago

Which of the following is NOT the same?

Inessa [10]

All are the same. It equals to the same thing.

4 0

3 years ago

Read 2 more answers

An alloy with an average grain diameter of 35 μm has a yield strength of 163 Mpa, and when it undergoes strain hardening, the gr

Lera25 [3.4K]

Answer:

$\sigma_y\ =210.2\ MPa$

Explanation:

Given that

d= 35 μm ,yield strength = 163 MPa

d= 17 μm ,yield strength = 192 MPa

As we know that relationship between diameter and yield strength

$\sigma_y=\sigma_o+\dfrac{K}{\sqrt d}$

$\sigma_y\ =Yield\ strength$

d = diameter

K =Constant

$\sigma_o\ =material\ constant$

So now by putting the values

d= 35 μm ,yield strength = 163 MPa

$163=\sigma_o+\dfrac{K}{\sqrt 35}$ ------------1

d= 17 μm ,yield strength = 192 MPa

$192=\sigma_o+\dfrac{K}{\sqrt 17}$ ------------2

From equation 1 and 2

$192-163=\dfrac{K}{\sqrt 17}-\dfrac{K}{\sqrt 35}$

K=394.53

By putting the values of K in equation 1

$163=\sigma_o+\dfrac{394.53}{\sqrt 35}$

$\sigma_o\ =96.31\ MPa$

$\sigma_y=96.31+\dfrac{394.53}{\sqrt d}$

Now when d= 12 μm

$\sigma_y=96.31+\dfrac{394.53}{\sqrt 12}$

$\sigma_y\ =210.2\ MPa$

4 0

3 years ago

Nitrogen gas is more abundant in our atmosphere than oxygen! However, nitrogen needs to be converted into different forms to be

Pavlova-9 [17]

Explanation:

(A)role of nittogen fixing bacteria

=Nitrogen-fixing bacteria, microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen (inorganic compounds usable by plants). More than 90 percent of all nitrogen fixation is effected by these organisms, which thus play an important role in the nitrogen cycle.

B)role of nitrifying bacteria

=Nitrifying bacteria convert the most reduced form of soil nitrogen, ammonia, into its most oxidized form, nitrate. In itself, this is important for soil ecosystem function, in controlling losses of soil nitrogen through leaching and denitrification of nitrate.

C)role of denitrifying bacteria

=Denitrifying bacteria converts nitrates back to nitrogen gas.

4 0

3 years ago