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Tanzania [10]
3 years ago
9

How did oxygen come up to make 21% of the earth's present atmosphere?

Chemistry
1 answer:
MakcuM [25]3 years ago
4 0
Tiny organisms known as cyanobacteria, or blue-green algae.
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Sediment layers stop lateral spreading when:
Xelga [282]

Answer:

Peepee poopoo!

Explanation:

7 0
3 years ago
One mole of an ideal gas with a volume of 1.0 L and a pressure of 5.0 atm is allowed to expand isothermally into an evacuated bu
Deffense [45]

Answer:

w= - 1.7173 kJ, q= 1.7173 kJ, q(rev) = 1717.3 J = 1.7173 kJ.

Explanation:

Okay, from the question we are given the information below;

Number of moles, n= 1 mole; initial volume, v(1) = 1.0 litres (L); pressure (p) = 5atm, final volume(v2) = 2.0 Litres(L) ; the workdone, w= not given; the heat, q and q(rev)= not given and the gas was said to expand isothermally.

So, this question is a question from the part of chemistry known as thermodynamics. Therefore, grip yourself we are delving into thermodynamics 'waters' now.

For expansion isothermally; the workdone, w= -nRT ln v2/v1.

Where T= temperature= 25° C = 298 k and R= gas constant.

Therefore; workdone, w = - 1 × 8.314 × 298 × ln(2/1).

Workdone,w= - 1717.32204643. =

- 1717.3 Joules (J).

==> Workdone,w= - 1.7173 kJ.

Then, we are to find q. q can be solved by using the first law of thermodynamics, which by mathematical representation is:

∆U= q + w. Where ∆U= change in internal enegy. Since the question is dealing with isothermal expansion, there is this rule that says for an isothermal expansion ∆U = 0.

Hence, 0 =q + [- 1717.3 Joules (J)].

q=1717.3 J = 1.7173 kJ.

Finally, the q(rev) which is= nRT ln (v2/V1).

q(rev) = 1 × 8.314 × 298 ln (2/1).

q(rev) = 1717.3 J = 1.7173 kJ.

PS: please note the negative signs in the workdone and the positive sign in the q(rev).

7 0
3 years ago
Why do health care professionals limit the number of radiation treatments that a person can be given
katovenus [111]
Radiation is s very powerful substance and can cause major health problems do the health care professionals limit the use to help not create sickness
6 0
3 years ago
Write a balanced equation from each cell notation:(b) Fe(s) | Fe²⁺(aq) | NO₃⁻(aq) | NO(g) | Pt(s)
tatiyna

The balanced redox reaction is

3Fe + 2NO₃⁻+ 8H+ → 3Fe²⁺ + 2NO + 4H2O

<h3>What is Galvanic cell? </h3>

It is a device that is used for the conversion of the chemical energy which is produce in the redox reaction into the electrical energy. It is also termed as the voltaic cell or electrochemical cell.

In the voltaic cell, at anode which is negative electrode of voltaic cell oxidation occurs and at the cathode which is positive electrode, reduction occurs

<h3>What is redox reaction? </h3>

The reaction in which both reduction and oxidation reaction takes place simultaneously is known as redox reaction.

<h3>What is oxidation reaction? </h3>

The reaction in which a substance or compound or species looses its electrons. In this reaction, oxidation state of an element increases.

<h3>What is reduction reaction? </h3>

The reaction in which a substance or compound or species accept the electrons. In this reaction, oxidation state of an element decreases.

The given two-half reactions are:

At anode:

3Fe → 3Fe²⁺ + 6e-

At cathode:

8H(+) + 2NO₃⁻ → 2NO + 4H2O

Redox reaction:

3Fe + 2NO₃⁻+ 8H+ → 3Fe²⁺ + 2NO + 4H2O

According to the voltaic cell, the half-cell reaction (1) shows oxidation reaction therefore, it occurs at anode and the half-cell reaction (2) shows reduction reaction therefore, it occurs at cathode.

Thus, we concluded that the redox reaction is

3Fe + 2NO₃⁻+ 8H+ → 3Fe²⁺ + 2NO + 4H2O

learn more about voltaic cell:

brainly.com/question/4052514

#SPJ4

7 0
1 year ago
What does homogeneous mixture of elements mean
mina [271]

If a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture. If its composition is uniform throughout, it is a homogeneous mixture.

8 0
3 years ago
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