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Harlamova29_29 [7]
3 years ago
9

What is a half-life in Chemistry?

Chemistry
1 answer:
makvit [3.9K]3 years ago
8 0

Answer:

half-life, in radioactivity, the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive ...

Explanation:

braniest

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Which of the following molecules have the ability to form hydrogen bonds with themselves?
ziro4ka [17]

Answer:

b. H3O c. H2SO4 d. HNO3

Explanation:

The hydrogen bonds can be form with molecules that have free electron pairs  and hydrogen atoms. In the case of NH4 molecule, the "free" electron pair in the nitrogen is not free because there is an hydrogen occuping them, and, in fact, this molecule has a positive charge. The other acids have free electron pairs in the oxigen, nitrogen or sulfur.

5 0
3 years ago
What reaction type is the followong reaction ​
Tems11 [23]

Answer:

its the fourth one please mark as brainlest

Explanation:

8 0
3 years ago
A full moon occurs when.??
Kamila [148]

Answer:

A full Moon occurs when the Moon appears as a complete circle in the sky. ... If the Moon is between the Earth and the Sun in its orbit, then the back side of the Moon is lit up and the side facing the Earth is in darkness.

Explanation:

3 0
3 years ago
Which of the following buffer systems would you use if you wanted to prepare a solution having a pH of approximately 9.5?Which o
zalisa [80]

Answer:

b. 0,08M NH₄⁺ / 0,12M NH₃

Explanation:

<em>The buffers are:</em>

<em>a. 0,08M H₂PO₄⁻ / 0,12M HPO₄²⁻</em>

<em>b. 0,08M NH₄⁺ / 0,12M NH₃</em>

It is possible to find out the pH of a buffer using Henderson-Hasselbalch formula:

<em>pH = pka + log₁₀ [A⁻] / [HA] </em><em>(1)</em>

Where A⁻ is the conjugate base of the weak acid, HA.

a. For the system H₂PO₄⁻ / HPO₄²⁻ pka is <u><em>7,198</em></u>. Replacing in (1)

pH = 7,198 + log₁₀ [0,12] / [0,08]

<em>pH = 7,37</em>

That means this buffer system don't have a pH of approximately 9,5

b. For the system NH₄⁺ / NH₃ pka is <em><u>9,3</u></em>. Replacing in (1)

pH = 9,3 + log₁₀ [0,12] / [0,08]

<em>pH = 9,50</em>

That means this buffer system is the buffer you need to use.

I hope it helps!

7 0
4 years ago
What volume of carbon dioxide is produced when 0.489 mol of calcium carbonate reacts completely according to the following react
Vilka [71]

Answer:

11.0L of carbon dioxide is produced

Explanation:

Balanced equation: CaCO_{3}(s)\rightarrow CaO(s)+CO_{2}(g)

According to balanced equation, 1 mol of CaCO_{3} produces 1 mol of CO_{2}

So, 0.489 mol of CaCO_{3} produces 0.489 mol of CO_{2}

Let's assume CO_{2} behaves ideally.

So, P_{CO_{2}}V_{CO_{2}}=n_{CO_{2}}RT

where P is pressure, V is volume , n is number of moles, R is gas constant and T is temperature in kelvin

Plug-in all the values in the above equation-

(1atm)\times V_{CO_{2}}=(0.489mol)\times (0.0821L.atm.mol^{-1}.K^{-1})\times (273K)

or, V_{CO_{2}}=11.0L

So, 11.0L of carbon dioxide is produced

4 0
3 years ago
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