How many atoms are in 2 Fe? 1 2 3 4

How many milliliters of 0.500 M NaOH should be added to 10.0 g of tris hydrochloride (FM 121.135) to give a pH of 7.60 in a fina

liubo4ka [24]

Answer:

41.64mL of NaOH 0.500M must be added to obtain the desire pH

Explanation:

It is possible to find pH of a buffer by using H-H equation, thus:

pH = pka + log [A⁻] / [HA]

Where [HA] is concentration of the weak acid TRIS-HCl and [A⁻] is concentration of its conjugate acid.

Replacing in H-H equation:

7.60 = 8.072 + log [A⁻] / [HA]

0.3373 = [A⁻] / [HA] (1)

10.0g of TRIS-HCl (Molar mass: 121.135g/mol) are:

10.0g ₓ (1mol / 121.135g) = 0.08255 moles of acid. That means moles of both the acid and conjugate base are:

[A⁻] + [HA] = 0.08255 (2)

Replacing (1) in (2):

0.3373 = 0.08255 - [HA] / [HA]

0.3373[HA] = 0.08255 - [HA]

1.3373[HA] = 0.08255

[HA] = 0.06173 moles

Thus:

[A⁻] = 0.08255 - 0.06173 = 0.02082 moles [A⁻]

The moles of A⁻ comes from the reaction of the weak acid with NaOH, that is:

HA + NaOH → A⁻ + H₂O + K⁺

Thus, you need to add 0.02082 moles of NaOH to produce 0.02082 moles of A⁻. As NaOH solution is 0.500M:

0.02082 moles NaOH ₓ (1L / 0.500mol) = 0.04164L of NaOH 0.500M =

<h3>41.64mL of NaOH 0.500M must be added to obtain the desire pH</h3>

3 0

2 years ago

How much heat is lost when 0.440 mol of steam condenses at 100 °C?

dusya [7]

Answer:

17,890 J

Explanation:

The amount of heat released by a gaseous substance when it condenses is given by the formula

$Q=n\lambda_v$

where

n is the number of moles of the substance

$\lambda_v$ is the latent heat of vaporization

The formula can be applied if the substance is at its vaporization temperature.

In this problem, we have:

n = 0.440 mol is the number of moles of steam

$\lambda_v=40,660 J/mol$ is the latent heat of vaporization of water

And the steam is already at 100C, so we can apply the formula:

$Q=(0.440)(40660)=17,890 J$

8 0

3 years ago

Regarding the Lyman series of hydrogen, calculate the frequency of the n = 5 line.

zvonat [6]

The Lyman series can be expressed in the formula 1/λ=RH(1−1/n2) where RH=1.0968×107m−1=13.6eVhc

Where n is a natural number greater than or equal to 2 (i.e. n = 2,3,4,...). Therefore, the lines seen in the image above are the wavelengths corresponding to n=2 on the right, to n=∞on the left (there are infinitely many spectral lines, but they become very dense as they approach to n=∞ (Lyman limit), so only some of the first lines and the last one appear).
The wavelengths (nm) in the Lyman series are all ultraviolet
:2 3 4 5 6 7 8 9 10 11
Wavelength (nm) 121.6 102.6 97.3 95 93.8 93.1 92.6 92.3 92.1 91.9 91.18 (Lyman limit)
In your case for the n=5 line you have to replace "n" in the above formula for 5 and you should get a value of 95 x 10^-9 m for the wavelength. then you have to use the other equation that convert wavelength to frequency.

4 0

2 years ago

How do potential energy diagrams represent energy transfer in chemical reactions?

Digiron [165]

Answer:

Hope this helps

Explanation:

Potential energy diagrams represent the energy transfer in chemical reactions in a diagram called a potential energy graph and/or a reaction progress curve. A potential energy diagram shows the adjustment in potential energy of a system as reactants are changed.

5 0

2 years ago

The radioactivity of U-235 is of low intensity. Why then were the people of Hiroshima exposed to high intensity radiation in the

Marina86 [1]

Answer:

Explanation:

What occurred then is as a result of nuclear fission. This occurs as the Uranium-235 split into two smaller nuclei while releasing high energy neutrons. These neutrons bombard existing U-235 in the atmosphere and this reaction continue in a spontaneous manner until a chain reaction is formed of U-235, whose fall out fills the environment. This process was what led to people been exposed to high intensity radiation in the days and months after the atomic bomb was dropped.

7 0

2 years ago