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4 years ago

Phenol red is an indicator that changes color over a range from ph=6.4 to ph=8.0. what is ka of phenol red?

1 answer:

7 0

First, we will get the average pH of the two given values:
average pH = (6.4+8) / (2) = 7.2
At this average pH, the concentration of the acid from the phenol red is equal to the concentration of the base.
pH = 7.2
[H+] = 10^(-7.2) = 6.3 * 10^-8

Phenol red has the general formula HA, this gives us:
HA <.......> H+ + A-
At pH = 7.2, [H+] = [A-]
Ka = [H+][A-]/ [HA]
Ka = [H+] = 6.3 x 10^-8

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2. Calculate how many moles of H2 would be produced if 0.250 mol of Fe reacts completely. (1 mark)

den301095 [7]

Hey there!:

Balanced Equation , for the reaction:

3 H₂SO₄(aq) + 2 Fe(s) → Fe₂(SO₄)₃(aq) + 3 H₂(g)

2 moles Fe ---------------------------------- 3 moles H₂

0.250 moles Fe ---------------------------- ( moles H₂ ) ??

____________________________________________

moles H₂ = 0.250 × 3 / 2

moles H₂ = 0.75 / 2

moles = 0.375 moles of H₂

Hope this helps!

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3 years ago

Hello I am working on naming compounds and wondering if you could help me figure out the name

Margaret [11]

Al2(SO4)3 aluminium sulfate

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4 years ago

Suppose a vodka martini contains 30% alcohol with the remaining portion of the drink composed of water. what is the solute in th

viktelen [127]

Solute - substance that dissolves.
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7 0

4 years ago

A gas exerts a pressure of 0.62 atm. Convert this to kPa and mmHg. Be sure to show your work.

IRINA_888 [86]

Answer:

The answer to your question is 0.62 atm = 62.82 kPa = 471.2 mmHg

Explanation:

Data

P = 0.62 atm

P = ? kPa

P = ? mmHg

Process

1.- Look for the conversion factor of atm to kPa and mmHg

1 atm = 101.325 kPa

1 atm = 760 mmHg

2.- Do the conversions

1 atm ----------------- 101.325 kPa

0.62 atm ------------ x

x = (0,62 x 101.325) / 1

x = 62.82 kPa

1 atm ------------------ 760 mmHg

0.62 atm ------------ x

x = (0.62 x 760)/1

x = 471.2 mmHg

4 0

4 years ago

Please help, don't understand this topic

Darya [45]

Answer:

Pangaea

Alfred Wegner

plate tectonics

Explanation:

What did Earth look like 250 million years ago? The continents of Earth were clustered together in formation that a scientist named Pangaea.The scientist that named "Pangaea" was a German scientist by the name of Alfred Wegner. He theorized that "Pangaea" split apart and the different landmasses, or continents, drifted to their current locations on the globe. Wegener's theories of plate movement became the basis for the development of the theory of plate tectonics.

8 0

3 years ago