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3 years ago

14

Find the Ka of nitrous acid given that a 0.20 M solution of the acid has a hydrogen ion concentration of 2.8*10-3 M. HNO2 (aq) ?

H+ (aq) + NO2- (aq)

1 answer:

Otrada [13]3 years ago

4 0

Answer:

3.92 x 10⁻⁵.

Explanation:

∵ [H⁺] = √(Ka.c)

∴ Ka = [H⁺]²/c = (2.8 x 10⁻³)²/(0.20) = 3.92 x 10⁻⁵.

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Suppose that 0.1000 mole each of H2and I2are placed in a 1.000-L flask, stoppered, and the mixture is heated to 425oC. At equili

Katen [24]

<u>Answer:</u> The value of equilibrium constant for the given reaction is 56.61

<u>Explanation:</u>

We are given:

Initial moles of iodine gas = 0.100 moles

Initial moles of hydrogen gas = 0.100 moles

Volume of container = 1.00 L

Molarity of the solution is calculated by the equation:

$\text{Molarity of solution}=\frac{\text{Number of moles}}{\text{Volume}}$

$\text{Molarity of iodine gas}=\frac{0.1mol}{1L}=0.1M$

$\text{Molarity of hydrogen gas}=\frac{0.1mol}{1L}=0.1M$

Equilibrium concentration of iodine gas = 0.0210 M

The chemical equation for the reaction of iodine gas and hydrogen gas follows:

$H_2+I_2\rightleftharpoons 2HI$

<u>Initial:</u> 0.1 0.1

<u>At eqllm:</u> 0.1-x 0.1-x 2x

Evaluating the value of 'x'

$\Rightarrow (0.1-x)=0.0210\\\\\Rightarrow x=0.079M$

The expression of $K_c$ for above equation follows:

$K_c=\frac{[HI]^2}{[H_2][I_2]}$

$[HI]_{eq}=2x=(2\times 0.079)=0.158M$

$[H_2]_{eq}=(0.1-x)=(0.1-0.079)=0.0210M$

$[I_2]_{eq}=0.0210M$

Putting values in above expression, we get:

$K_c=\frac{(0.158)^2}{0.0210\times 0.0210}\\\\K_c=56.61$

Hence, the value of equilibrium constant for the given reaction is 56.61

6 0

3 years ago

A 20.0 gram sample of an element contains 4.95 x 1023 atoms. what is the element?

Sonja [21]

You will want to find how many grams are in a whole mole so you know which element it is. To do this, find out how much of a mole you have.

4.95 x 10^23 atoms / 6.022 x 10^23 atoms (one whole mole of any element) = .8219860511 or ~82% of 1 mole

Now we know that, find what to multiply 20 g by to get the rest of the mole.

1 mole / .8219860511 mole = 1.216565657

20 g x 1.216565657 = ~24.33 g / mol

Now that you have grams per mole, you can look at the periodic table and the molar masses to see which this number is closely aligned.

Your answer is Magnesium (Mg), which has a molar mass of 24.305 g

7 0

3 years ago

you have a solution of water and salt. if the total solution weighs 50 grams and the salt weighs 4 grams. what is the percent co

Natali5045456 [20]

Answer:

92%

Explanation:

I believe. Hope this was helpful.

8 0

3 years ago

At a certain temperature the vapor pressure of pure thiophene is measured to be . Suppose a solution is prepared by mixing of th

Lesechka [4]

Answer:

0.35 atm

Explanation:

It seems the question is incomplete. But an internet search shows me these values for the question:

" At a certain temperature the vapor pressure of pure thiophene (C₄H₄S) is measured to be 0.60 atm. Suppose a solution is prepared by mixing 137. g of thiophene and 111. g of heptane (C₇H₁₆). Calculate the partial pressure of thiophene vapor above this solution. Be sure your answer has the correct number of significant digits. Note for advanced students: you may assume the solution is ideal."

Keep in mind that if the values in your question are different, your answer will be different too. <em>However the methodology will remain the same.</em>

First we <u>calculate the moles of thiophene and heptane</u>, using their molar mass:

137 g thiophene ÷ 84.14 g/mol = 1.63 moles thiophene

111 g heptane ÷ 100 g/mol = 1.11 moles heptane

Total number of moles = 1.63 + 1.11 = 2.74 moles

The<u> mole fraction of thiophene</u> is:

1.63 / 2.74 = 0.59

Finally, the <u>partial pressure of thiophene vapor is</u>:

Partial pressure = Mole Fraction * Vapor pressure of Pure Thiophene

Partial Pressure = 0.59 * 0.60 atm

Pp = 0.35 atm

3 0

3 years ago

Suppose that a certain fortunate person has a net worth of $77.0 billion ($). If her stock has a good year and gains $3.20 billi

marissa [1.9K]

Answer:

New net worth to three significant figures = $80.2 billion

Dollars are given to charity = $100,250,000

Explanation:

Net worth = $77.0 billion

stock Gains = $3.20 billion

New net worth = $77.0 billion + $3.20 billion = $80.20 billion

New net worth to three significant figures = $80.2 billion

One-eighth of a percent = (1/8 x 1) / 100 = 0.00125

Dollars are given to charity = 0.00125 X $80.2 billion = $100,250,000

Or

$80,200,000,000/100 = $802,000,000

3 0

3 years ago