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krek1111 [17]
4 years ago
8

What is the ph of a buffer prepared by adding 0.809 mol of the weak acid ha to 0.608 mol of naa in 2.00 l of solution? The disso

ciation constant ka of ha is 5.66×10−7.
Chemistry
1 answer:
Anarel [89]4 years ago
5 0

The pH of the buffer is 6.1236.

Explanation:

The strength of any acid solution can be obtained by determining their pH. Even the buffer solution strength of the weak acid can be determined using pH. As the dissociation constant is given, we can determine the pKa value as the negative log of dissociation constant value.

pKa=-log[H] = - log [ 5.66 * 10^{-7}]\\ \\pka = 7 - log (5.66)=7-0.753=6.247\\\\pka = 6.247

The pH of the buffer can be known as

pH = pK_{a} + log[\frac{[A-]}{[HA]}}]

The concentration of [A^{-}] = Moles of [A]/Total volume = 0.608/2 = 0.304 M\\

Similarly, the concentration of [HA] = \frac{Moles of HA}{Total volume} = \frac{0.809}{2} = 0.404

Then the pH of the buffer will be

pH = 6.247 + log [ 0.304/0.404]

pH = 6.247 + log 0.304 - log 0.404=6.247-0.517+0.3936=6.1236

So, the pH of the buffer is 6.1236.

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yanalaym [24]

Answer:

d. 3 signals: a singlet, a doublet, and a septet

Explanation:

In this case, we can start with the structure of (CH_3)_2CHOCH_3 . When we draw the molecule we will obtain <u>2-methoxypropane</u> (see figure 1).

In 2-methoxypropane we will have three signals. The signal for the CH_3  groups in the left, the CH  and the CH_3  in the right. Lets analyse each one:

-) CH_3  in the right

In this carbon, we dont have any hydrogen as neighbors. Therfore we will have <u>singlet</u> signal in this carbon.

-) CH

In this case, we have 6 hydrogen neighbors ( the two methyl groups in the left). So, if we follow the <u>n + 1 rule</u> (where n is the amount of hydrogen neighbors):

multiplicity~=~n+1~=~6~+~1~=~7

For this carbon we will have a <u>septet</u>.

-) CH_3  in the left

In this case we have only 1 hydrogen neighbor (the hydrogen in CH ). So, if we use the n+1 rule we will have:

multiplicity~=~n+1~=~1~+~1~=~2

We will have a doublet

With all this in mind the answer would be:  

<u>d. 3 signals: a singlet, a doublet, and a septet </u>

<u />

See figure 2 to further explanations

4 0
3 years ago
A basketball player jumps straight up to dunk a basketball. The basketball player's speed increases as she returns to the
katen-ka-za [31]

Options :

The upward force is greater than the downward force.

The downward force is greater than the upward force.

The rightward force is greater than the leftward force.

The leftward force is greater than the rightward force.

Answer:

The downward force is greater than the upward force.

Explanation:

When the player jumps to dunk a basket ball, it requires an upward force exerted on the person due to the push by the person to jump, after dunking the basket ball, the player attains maximum height, where his final velocity becomes zero and his direction changes (from upward to downward), at this point his velocity increases due to the additional force exerted on the player due to the Earth's Gravitational pull - which is a downward force which acts on an object).

Hence, it could be concluded that the increase in speed of the basketball player as she returns to the ground means that the downward force is greater than the upward force acting on the player.

7 0
3 years ago
White phosphorus melts and then vaporizes at high temperatures. The gas effuses at a rate that is 0.404 times that of neon in th
Soloha48 [4]

White phosphorus melts and then vaporizes at high temperatures. The gas effuses at a rate that is 0.404 times that of neon in the same apparatus under the same conditions-There are 4 atoms of P in the molecule

Explanation:

Ar=30,97g/mol

R_{Px/R_Ne}=\sqrt{Mr(Ne)/Mr(Px)}=0,404

0,404=\sqrt{20,18/30,97*x}

0,404^{2}=20,18/30,97*x

X=20,18/30,97*0,163

X=4

There are 4 atoms of P in the molecule

White phosphorus melts and then vaporizes at high temperatures. The gas effuses at a rate that is 0.404 times that of neon in the same apparatus under the same conditions-There are 4 atoms of P in the molecule

8 0
3 years ago
What is the frequency of an X-ray that has a wavelength of 1.5 x 10 -9 m? The speed of electromagnetic radiation is 3.0 x 10 8 m
AlexFokin [52]

Answer:

2.0x10¹⁷ Hz is the frequency of the X-ray

Explanation:

We can find the frequency of a wave of energy from the wavelenght and its speed using the formula:

v = λƒ

<em>Where v is speed (For electromagnetic radiation = 3.0x10⁸m/s)</em>

<em>λ is the wavelength in meters = 1.5x10⁻⁹m</em>

<em>And f is the frequency in s⁻¹ = Hz</em>

<em />

Replacing:

3.0x10⁸m/s = 1.5x10⁻⁹m*ƒ

3.0x10⁸m/s / 1.5x10⁻⁹m = f

f =

<h3>2.0x10¹⁷ Hz is the frequency of the X-ray</h3>

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3 0
3 years ago
A teacher gives students four liquids commonly found in the kitchen - vinegar, apple juice, dish detergent, and milk - and pH in
VMariaS [17]

Answer:

1. Comparative

2. Independent variable

3. The pH is the Dependent variable

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