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Strike441 [17]
2 years ago
13

URGENT PLEASE HELP!! Earth science!!

Chemistry
1 answer:
aev [14]2 years ago
3 0

Answer:

URGENT PLEASE HELP!! Earth science!!

What stages of development are represented by the Group 2 and Group 3 stars? Describe these

groups in terms of their relative age, size, brightness, and temperature.

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Determine the pH of (a) a 0.40 M CH3CO2H solution, (b) a solution that is 0.40 M CH3CO2H and 0.20 M NaCH3CO2
elena-s [515]

Answer:

a) pH = 2.573

b) pH = 4.347

Explanation:

a) weak acid: CH3COOH

  • CH3COOH + H2O ↔ CH3COO- + H3O+

∴ Ka = 1.8 E-5 = [H3O+][CH3COO-] / [CH3COOH]

∴ <em>C</em> CH3COOH = 0.40 M

mass balance:

⇒ 0.40 M = [CH3COO-] + [CH3COOH].........(1)

charge balance:

⇒ [H3O+] = [CH3COO-].........(2)

(2) in (1):

⇒ [CH3COOH] = 0.40 - [H3O+]

replacing in Ka:

⇒ Ka = 1.8 E-5 = [H3O+]² / ( 0.40 - [H3O+] )

⇒ [H3O+]² = 7.2 E-6 - 1.8 E-5[H3O+]

⇒ [H3O+]² + 1.8 E-5[H3O+] - 7.2 E-6 = 0

⇒ [H3O+] = 2.6743 E-3 M

∴ pH = - Log [H3O+]

⇒ pH = 2.573

b) balanced reations:

  • CH3COONa + H2O → Na+  +  CH3COO-
  • CH3COOH + H2O ↔ CH3COO-  +  H3O+

∴ <em>C</em> CH3COOH = 0.40 M

∴ <em>C</em> CH3COONa = 0.20 M

mass balanced:

⇒ <em>C</em> CH3COOH + <em>C</em> CH3COONa = [CH3COO-] + [CH3COOH]

⇒ 0.60 = [CH3COO-] + [CH3COOH]......(1)

charge balanced:

⇒ [H3O+] + [Na+] = [CH3COO-]

∴ [Na+] = 0.20 M

⇒ [H3O+] + 0.20 M = [CH3COO-]........(2)

(2) in (1):

⇒ 0.60 M = ( [H3O+] + 0.20 ) + [CH3COOH]

⇒ [CH3COOH] = 0.40 - [H3O+]

replacing in Ka:

⇒ 1.8 E-5 = ([H3O+])([H3O+] + 0.20) / (0.40 - [H3O+])

⇒ 7.2 E-6  - 1.8 E-5[H3O+] = [H3O+]² + 0.20[H3O+]

⇒ [H3O+]² + 0.20[H3O+] - 7.2 E-6 = 0

⇒ [H3O+] = 4.499 E-5 M

⇒ pH = 4.347

7 0
3 years ago
LAST QUESTION!!!! 50 POINTS!!! PLEASE ANSWER!!! &lt;3
matrenka [14]

Answer:

Fats are created by the ribsome to store excess energy

5 0
2 years ago
Read 2 more answers
Atoms of element X weigh 32 times more than atoms of element Y. A compound has the formula: XY2 The ratio of the mass of X to th
tamaranim1 [39]

Answer:

16:1

Explanation:

Atoms of element X weigh 32 times more than atoms of element Y. We can write this in a symbolic way.

mX = 32 mY   [1]

where,

  • mX and mY are the masses of X and Y, respectively

A compound has the formula: XY₂, that is, in 1 molecule of XY₂ there is 1 atom of X and 2 atoms of Y. The ratio of the mass of X to the mass of Y in this compound equals:

mX/2 mY  [2]

If we substitute [1] in [2], we get:

mX/2 mY = 32 mY/2 mY = 16 = 16:1

4 0
3 years ago
The amplitude of a wave is the distance between a point on one wave and the identical point on the next wave T or F?
MaRussiya [10]
The amplitude of a wave is the distance between a point on one wave and the identical point on the next wave. The period and wavelength of a wave are inversely proportional.
7 0
3 years ago
The following equation is one way to prepare oxygen in a lab. 2KClO3 → 2KCl + 3O2 Molar mass Info: MM O2 = 32 g/mol MM KCl = 74
Alex73 [517]
From  the  equation  above   the  reacting   ratio  of  KClO3   to  O2  is  2:3 therefore  the  number  of  moles  of  oxygen  produced  is  ( 4 x3)/2 =  6 moles  since   four  moles  of  KClO3  was  consumed
mass=relative  formula mass  x  number  of  moles
That  is   32g/mol x 6  moles  =192grams


8 0
3 years ago
Read 2 more answers
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