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crimeas [40]
3 years ago
12

The radioisotope radon-222 has a half-life of 3.8 days. How much of a 73.9-g sample of radon- (3 222 would be left after approxi

mately 23 days?​
Chemistry
1 answer:
Novay_Z [31]3 years ago
6 0

Answer:

1.115 g

Explanation:

Applying,

R = R'2^{n/t}................... Equation 1

Where R = original sample of radon-222, R' = sample of radon-222 left after decay, n = Total time, t = half-life.

make R' the subject of the equation

R' = R/(2^{n/t})............... Equation 2

From the question,

Given: R = 73.9 g, n = 23 days, t = 3.8 days.

Substitute these values into equation 2

R' = 73.9/(2^{23/3.8})

R' = 73.9/2^{6.05}

R' = 1.115 g

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How many electrons does calcium lose when forming an ionic bond with another ion?
Advocard [28]
The correct answer is answer choice B, 2. Calcium is in Column 2, meaning that it has 2 electrons in its outermost energy level. These two electrons must be lost for it to form an ionic bond with another element and become stable.

Questions like these can be easily answered if you have a periodic table on hand. Elements in Column 1 need to lose 1 electron to form ionic bonds, elements in Column 2 need to lose 2, and so on. Keep in mind, however, that elements in the center of the table are more likely to form metallic or covalent bonds, and elements in Columns 16 and 17 need to gain 2 and 1 electrons, respectively.
6 0
4 years ago
Suppose you want to prepare a buffer with a pH of 4.59 using formic acid. What ratio of [sodium formate]/[formic acid) do you ne
katrin [286]

Answer:

7.08

Explanation:

To solve this problem we'll use the <em>Henderson-Hasselbach equation</em>:

  • pH = pka + log\frac{[A^-]}{[HA]}

Where \frac{[A^-]}{[HA]} is the ratio of [sodium formate]/[formic acid] and pka is equal to -log(Ka), meaning that:

  • pka = -log (1.8x10⁻⁴) = 3.74

We<u> input the data</u>:

  • 4.59 = 3.74 + log\frac{[A^-]}{[HA]}

And<u> solve for </u>\frac{[A^-]}{[HA]}:

  • 0.85 = log\frac{[A^-]}{[HA]}
  • 10^{(0.85)}=\frac{[A^-]}{[HA]}
  • \frac{[A^-]}{[HA]} = 7.08
3 0
3 years ago
The IUPAC rules permit the use of common names for a number of familiar phenols and aryl ethers. These common names are listed h
fgiga [73]

Explanation:

a. Vanillin(4-hydroxy-3-methoxybenzaldehyde):

In its structure hydroxl group will be present on para position of the benzaldehyde ring and methoxy group on meta position.

b. Thymol (2-isopropyl-5-methylphenol):

In its structure isopropyl group will be present on ortho position of the phenol ring and methyl group on meta position.

c. Carvacrol (5-isopropyl-2-methylphenol):

In its structure isopropyl group will be present opposite to methyl group which is present ortho position in a phenol ring.

d. Eugenol (4-allyl-2-methoxyphenol):.

In its structure allyl group will be present on para position of the phenol ring and methoxy group on ortho position.

e. Gallic acid (3,4,5-trihydroxybenzoic acid):

In its structure hydroxyl group will be present on both meta positions and on para position of the benzoic acid ring.

f. Salicyl alcohol (o-hydroxybenzyl alcohol):

In its structure, -CH_2OH group is linkedto benzene ring and in respect to that hydroxyl group is present at ortho position of the ring.

6 0
3 years ago
How many grams of lithium are in a 1320 [mAh] cell phone battery? Note that [mAh] is a unit of charge.
AURORKA [14]

Answer:

0.396 grams of lithium

Explanation:

Lithium-ion batteries have the main feature of using lithium salts as a "bridge" between the positive pole (anode) to the negative (cathode) to allow the passage of energy that will give life to our device. In the case of lithium polymer batteries, the difference is that the lithium salt is contained in a polymer, or gel, to keep it safe from spills.

In both cases, when the battery is discharging, lithium ions travel from the cathode to the anode through their "bridges" to supply the energy until all the ions are in the anode, it is at this time when the battery is out of stock The ions travel in the opposite direction during charging (from the anode to the cathode).

<u>The calculation used to determine the amount of lithium that the lithium cell batteries have is as follows</u>:

0.3 x amp hour capacity = g of lithium

where amp hour = Ah

<u>In our case</u>:

0.3 x 1.32 = 0.396 g of lithium

5 0
3 years ago
I need helppppppppppp. Btw the question is “Select three populations shown in the prairie ecosystem.”
nadezda [96]
I think it’s all of the above :))
6 0
3 years ago
Read 2 more answers
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