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Eva8 [605]
3 years ago
12

Phenolphthalein has a pka of 9.7 and is colorless in its acid form and pink in its basic form. part a for ph= 2.0 calculate [in−

]/[hin].
Chemistry
2 answers:
Tresset [83]3 years ago
8 0

Answer:

1.9953 × 10⁻⁸

Explanation:

Considering the Henderson- Hasselbalch equation for the calculation of the pH of the indicator as:

pH = pKa + log[In⁻]/[HIn]

Where Ka is the dissociation constant of the acid.

Given, pKa = 9.7

pH = 2.0

So,  

2.0 = 9.7 + log[In⁻]/[HIn]

log[In⁻]/[HIn]  = - 7.7

<u>[In⁻]/[HIn] = Antilog (-7.7) = 1.9953 × 10⁻⁸</u>

Karo-lina-s [1.5K]3 years ago
4 0
Use the h-h equation! 

pH = pKa + log[In-/HIn]
2.0 = 9.7 + log[In-/HIn]
-7.7 = log[In-/HIn]
10^-7.7 = [In-/HIn]
[In-/HIn] = 1.995 x 10^-8

Hope this helps!
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Answer:

The value of an integer x in the hydrate is 10.

Explanation:

Molarity=\frac{Moles}{Volume(L)}

Molarity of the solution = 0.0366 M

Volume of the solution = 5.00 L

Moles of hydrated sodium carbonate = n

0.0366 M=\frac{n}{5.00 L}

n=0.0366 M\times 5 mol=0.183 mol

Mass of hydrated sodium carbonate = n= 52.2 g

Molar mass of hydrated sodium carbonate = 106 g/mol+x18 g/mol

n=\frac{\text{mass of Compound}}{\text{molar mass of compound}}

0.183 mol=\frac{52.2 g}{106 g/mol+x\times 18 g/mol}

106 g/mol+x\times 18 g/mol=\frac{52.2 g}{0.183 mol}

Solving for x, we get:

x = 9.95 ≈ 10

The value of an integer x in the hydrate is 10.

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A system gains 652 kJ of heat, resulting in a change in internal energy of the system equal to +241 kJ. How much work is done?
levacccp [35]

Answer:

-411 kj

Explanation:

We solve by using this formula

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This formula is the first law of thermodynamics

Change in internal energy U = +241

Heat gained by system Q = 652

Putting the value into the equation

+241 = 652 + W

Workdone = 241 - 652

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3 years ago
Radioactive radium has a half-life of approximately 1,599 years. The initial quantity is 13 grams. How much (in grams) remains a
Luda [366]

The quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.

<h3>What is half life period? </h3>

The time taken by substance to reduce to its half of its initial concentration is called half life period.

We will use the half- life equation N(t)

N e^{(-0.693t) /t½}

Where,

N is the initial sample

t½ is the half life time period of the substance

t2 is the time in years.

N(t) is the reminder quantity after t years .

Given

N = 13g

t = 350 years

t½ = 1599 years

By substituting all the value, we get

N(t) = 13e^(0.693 × 50) / (1599)

= 13e^(- 0.368386)

= 13 × 0.691

= 8.98

Thus, we calculated that the quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.

learn more about half life period:

brainly.com/question/20309144

#SPJ4

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