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3 years ago

What is the average atomic mass (in amu) of element M?

1 answer:

4 0

An atomic mass unit (symbolized AMU or amu) is defined as precisely 1/12 the mass of an atom of carbon-12. The carbon-12 (C-12) atom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the average of the proton rest mass and the neutron rest mass.

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What concentrations of acetic acid (pKa = 4.76) and acetate would be required to prepare a 0.15 M buffer solution at pH 5.0? Not

Leni [432]

Answer:

Acetic acid 0,055M and acetate 0,095M.

Explanation:

It is possible to prepare a 0,15M buffer of acetic acid/acetate at pH 5,0 using Henderson-Hasselblach formula, thus:

pH = pka + log₁₀ [A⁻]/[HA] -Where A⁻ is acetate ion and HA is acetic acid-

Replacing:

5,0 = 4,76 + log₁₀ [A⁻]/[HA]

1,7378 = [A⁻]/[HA] (1)

As concentration of buffer is 0,15M, it is possible to write:

[A⁻] + [HA] = 0,15M (2)

Replacing (1) in (2):

1,7378[HA] + [HA] = 0,15M

2,7378[HA] = 0,15M

[HA] = 0,055M

Thus, [A⁻] = 0,095M

That means you need acetic acid 0,055M and acetate 0,095M to obtain the buffer you need.

i hope it helps!

7 0

3 years ago

6. India is a country connected to the continent of Asia. India used to be far apart

velikii [3]

I can’t see what image you have to refer too but India is now part of the rest of Asia due to continental plates running into eachother.

4 0

3 years ago

Consider the change given below. At constant pressure, is work done by the system on the surroundings? By the surroundings on th

alexira [117]

Answer : At constant pressure work is done by the system on the surroundings.

Explanation :

Work done : Any quantity that flows across the boundary of a system during a change in its state and it completely convertible into the lifting of a weight in the surroundings.

Formula for work done is:

$w=-p_{ext}dV$

Sign convention :

When volume expand then system work that means work done by the system.

w = (-ve)

When volume compress then surrounding work that means work done on the system.

w = (+ve)

The given reaction is:

$Hg(l)\rightarrow Hg(g)$

This is a evaporation process in which phase changes from liquid state to gaseous state at constant temperature.

At constant pressure, work depends only on volume.

In evaporation process, the volume expand that means work is done by the system on the surroundings.

Sign convention is, w = (-ve)

Thus, at constant pressure work is done by the system on the surroundings.

7 0

3 years ago

What is the molecular formula of the hydrocarbon whose molar mass is 536 g/mol and contains 89.55 w/w% carbon?

leonid [27]

Given the percentage composition of HC as C → 81.82 % and H → 18.18 %

So the ratio of number if atoms of C and H in its molecule can will be:

C : H = 81.82 12 : 18.18 1 C : H = 6.82 : 18.18 = 6.82 6.82 : 18.18 6.82 = 1 : 2.66 ≈ 3 : 8

So the Empirical Formula of hydrocarbon is:

C 3 H 8

As the mass of one litre of hydrocarbon is same as that of C O 2 The molar mass of the HC will be same as that of C O 2 i.e 44 g mol

Now let Molecular formula of the HC be ( C 3 H 8 ) n

Using molar mass of C and H the molar mass of the HC from its molecular formula is:

( 3 × 12 + 8 × 1 ) n = 44 n So 44 n = 44 ⇒ n = 1

Hence the molecular formula of HC is C 3 H 8

Does that help?

7 0

3 years ago

How many protons and electrons are present in an argon atom?

scoray [572]

Protons: 7Electrons:7

4 0

3 years ago

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