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3 years ago

The ph of 0.255 m hcn is 4.95. What is the value of ka for hydrocyanic acid?

Chemistry

1 answer:

Lera25 [3.4K]3 years ago

5 0

Answer:

Ka = 4.9 X 10^-9

Explanation:

when the pH is 4.95

the [H+] = 10^-4.95

[H+] = 1.122 e-5

since the equilibrium equation is:

HCN <=> 1 mole H+ & 1 mole CN-

then

[H+] = [CN-]

when

HCN <=> H+ & CN-

Ka = [ H+] [CN-] / [HCN]

Ka = [ 1.122 e-5] [ 1.122 e-5] / [0.255]

Ka = 1.256 e-10 / 0.255

Ka = 4.94 e-9

which rounds off to 2 sig figs into

Ka = 4.9 X 10^-9

======================

p.s. it was the pH pf 4.95 that limited the calculations to 2 sig figs

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Talja [164]

Answer:

2–methyl–3–propylheptane.

Explanation:

The name of the compound can be obtained as follow:

1. Identify the functional group of the compound.

2. Determine the name of the compound by determining the longest continuous carbon chain.

3. Identify the substituent group attached.

4. Locate the position of the substituent group by giving it the lowest possible count. Where there are two or more different substitutent group attached to the compound, name them alphabetically.

5. Name the compound by combining

the above steps.

Thus, we can name the compound as follow:

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Propyl i.e –C3H7

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5. The name of the compound is:

2–methyl–3–propylheptane.

6 0

3 years ago

The mole concept is important in chemistry because 1. it allows us to distinguish between elements and compounds. 2. it provides

Rufina [12.5K]

Answer:
<span>The mole concept is important in chemistry because, "</span>Atoms and molecules are very small and the mole concept allows us to count atoms and molecules by weighing macroscopic amounts of material".

Explanation:
To understand this question lets take an example of Hydrogen atom. Let suppose you need to react Hydrogen with Oxygen. You need exactly Two Hydrogen atoms and one Oxygen atom to form one water molecule.
The mass of 1 hydrogen atom is 1.76 × 10⁻²⁴ grams. How will you count the Hydrogen atoms??? How can you measure exactly for 1 Million Hydrogen Atoms???
Answer to these questions and Calculations lies in Mole. It is found that 1 Mole of Hydrogen weights exactly 1.008 gram and contains 6.022 × 10²³ atoms. Now, having this reference in hand you can calculate for any number of Hydrogen atoms.

Result:
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3 years ago

10mL volume of 75mM EtOH is necessary for an experiment. What volumes of 1M EtOH and water should be mixed to obtain the working

kenny6666 [7]

Answer: Volume of the 1M EtOH and water should be 0.75 ml and 9.25 ml respectively to obtain the working concentration.

Explanation:

According to the dilution law,

$C_1V_1=C_2V_2$

where,

$C_1$ = molarity of stock solution = 1M

$V_1$ = volume of stock solution = ?

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$V_2$ = volume of diluted solution = 10 ml

Putting in the values we get:

$1M\times V_1=0.075M\times 10ml$

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3 years ago

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mojhsa [17]

Answer:

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Explanation:

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Advocard [28]

Answer:it’s c

Explanation:just got it on edge

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3 years ago

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