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gayaneshka [121]
3 years ago
5

Calculation: If you have a pH of 5.5 for a weak acid with a pKa of 4.76, then is there more A- or more HA in the solution? Expla

in why in words using your knowledge of positive or negative log numbers.
Chemistry
2 answers:
devlian [24]3 years ago
6 0

Answer:

lets set the ratio -A/HA as R:

pH = pKa + log(R,10) => pKa + log10(R)

pH = 5.5

pKa = 4.76

R => 10^(pH - 4.76)

10^(pH - 4.76) => 5.4954

Given R (-A/HA) a number bigger than 1, then the concentration of  -A is bigger than HA

Explanation:

meriva3 years ago
6 0

Answer:

There is more A⁻ than HA in the solution  

Explanation:

The equation for the ionization of a weak acid is

HA + H₂O ⇌H₃O⁺ + OH⁻

When HA and A⁻ are present in comparable amounts, we can use the Henderson-Hasselbalch equation:

\begin{array}{rcl}\text{pH} &=& \text{pK}_{\text{a}} + \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\5.5 & = & 4.76 + \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\\0.74 & = & \log\dfrac{[\text{A}^{-}]}{\text{[HA]}}\\\end{array}

0.74 is a positive number, and a number must be greater than one for its logarithm to be positive. That is,

\begin{array}{rcl}\dfrac{[\text{A}^{-}]}{\text{[HA]}} & > & 1\\\\\textbf{[A]}^{-} & > & \textbf{[HA]}\\\end{array}

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In the periodic table, the elements that are adjacent to the "stair step" are called _____. actinide series nonmetals metalloids
yawa3891 [41]

Answer:-

Metalloids

Explanation:-

The stair step line is a line in the periodic table that divides the metals on one side and the non metals on the other side. So the elements which lie on the stair step line must have properties in between those exhibited by the metals and those by the non metals.

Such elements we know are called metalloids. Thus In the periodic table, the elements that are adjacent to the "stair step" are called metalloids.

5 0
4 years ago
Water has a higher boiling point than acetone does. Which of the following statements about water and acetone in the liquid stat
Semenov [28]

Answer:

Water's boiling point is higher than acetone's one due to the stronger intermolecular forces it has in liquid phase.

Explanation:

Hello.

In this case, since no options are given we can infer from the statement that due to water's higher boiling point than acetone we can conclude that when they are in liquid state, water has stronger intermolecular forces which allow its particles to be held in a stronger way in comparison to the acetone's molecules, for that reason, more energy will be required in order to separate them and promote the boiling process, which is attained via increasing the temperature. Besides, less energy will be required for the separation of the acetone's molecules in order to boil it when liquid, therefore, a lower temperature is required.

In such a way, we can sum up that water's boiling point is higher than acetone's one due to the stronger intermolecular forces it has in liquid phase.

Regards.

7 0
4 years ago
Which of the following mixture types is characterized by the settling of particles?
torisob [31]
The answer is B. Suspension. Suspension mixtures are composed of two or more materials mixed together wherein the solute particles are usually larger than those found in a solution or colloid. In cases of solid-fluid suspension mixtures, the solid solute particles tend to settle at the bottom of the mixture after some time.
8 0
3 years ago
Coefficients are used in a chemical formula to show the number of each element. True or False
ANTONII [103]

Answer:

The same number of each element present before the reaction takes place must also be present on the product side of the equation. Coefficients are placed in front of a chemical formula to show the number of moles of that substances that are necessary for the reaction to occur.

Explanation:

5 0
3 years ago
Copper has two naturally occurring isotopes. Cu−63 has a mass of 62.939 amu and relative abundance of 69.17%.
fiasKO [112]
The answer is 64.907 amu.

The atomic mass of an element is the average of the atomic masses of its isotopes. The relative abundance of isotopes must be taken into consideration, therefore:
atomic mass of copper = atomic mass of isotope 1 * abundance 1 + atomic mass of isotope 2 * abundance 2

We know:
atomic mass of copper = 63.546 amu
The atomic mass of isotope 1 is: 62.939 amu
The abundance of isotope 1 is: 69.17% = 0.6917
The atomic mass of isotope 1 is: x
The abundance of isotope 2: 100% - 69.17% = 30.83% = 0.3083

Thus:
63.546 amu = 62.939 amu * 0.6917 + x * 0.3083
63.546 <span>amu = 43.535 amu + 0.3083x
</span>⇒ 63.546 amu - 43.535 amu = 0.3083x
⇒ 20.011 amu = 0.3083x
   ⇒ x = 20.011 amu ÷ 0.3083 = 64.907 amu
7 0
3 years ago
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