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2 years ago

You have 700,000 atoms of a radioactive substance. After 2 half-lives have past, how

Chemistry

2 answers:

max2010maxim [7]2 years ago

6 0

Answer:

175,000

Explanation:

700,000/4=175,000

2 half-lives = approx 175,000

Ganezh [65]2 years ago

4 0

The number of atoms that remains after 2 half-lives given that it was originally 700,000 atoms is 175000 atoms.

<h3>What is a radioactive substance?</h3>

Radiation in the form of radiant particles or rays, is the result of a nuclear disintegration. Radioactive materials are atoms that have stored energy and may disintegrate in the future, releasing radiation.

Data obtained from the question

Original amount (N₀) = 700,000 atoms

Number of half-lives (n) = 2

Amount remaining (N) =?

How to determine the amount remaining

The amount remaining after 2 half-lives can be obtained as illustrated below:

N = N₀ / 2ⁿ

N = 700,000 / 4

N = 175000 atoms

Hence, 175000 atoms remain.

Learn more about the radioactive substance here:

brainly.com/question/27755919

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Can the pH scale be utilized for all acids (Arrhenius, Bronsted-Lowry, and Lewis)? Give examples of substances from each definit

CaHeK987 [17]

Answer:

Explanation:

The pH scale is a scale graduated from 0-14 which shows the degree of acidity of alkalinity of a substance. The pH scale is graduated in such a way that 0-6.9 indicates acidity, 7.0 indicate a neutral substance, while a pH of 8-14 indicates alkalinity respectively.

There are three main definitions of acids/bases

- Arrhenius definition

-Brownstead-Lowry definition

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Arrhenius explains acids as any substance that produces hydrogen ions as its only positive ion in solution while a base produces hydroxide ions as its only negative ion in solution. The pH scale is based on corresponding values of pH derived from aqueous solutions of these substances.

However, not all acids/bases produces hydrogen or hydroxide ions in solution. Brownstead-Lowry definition of acids and Lewis definition of acids could be extended to nonaqueous media where the pH can not be measured as there are no hydrogen or hydroxide ions present in the solution.

This implies that pH measurement may not apply to acids/bases in the all the categories of acids/bases hence it can not be utilized for all acids and bases.

Arrhenius - sodium carbonate

Brownstead-Lowry - concentrated HF

Lewis acid - AlCl3

6 0

3 years ago

A mixture of carbon dioxide and helium gases is maintained in a 7.91 L flask at a pressure of 1.42 atm and a temperature of 33 °

Crank

Answer:

The gas mixture contains 1.038 grams of helium

Explanation:

Step 1: Data given

Volume of the flask = 7.91 L

Total Pressure = 1.42 atm

Temperature = 33 °C

Mass of CO2 = 8.25 grams

Molar mass of CO2 = 44.01 g/mol

Molar mass of He = 4 g/mol

Step 2: Calculate total number moles of gas

p*V = n*R*T

⇒ p = the pressure = 1.42 atm

⇒ V = the volume = 7.91 L

⇒ n= the number of moles = TO BE DETERMINED

⇒ R = the gas constant = 0.08206 L* atm/K*mol

⇒ T = the temperature = 33 °C = 306 Kelvin

n = (p*V)/(R*T)

n = (1.42*7.91)/(0.08206 * 306)

n = 0.447 moles

Step 3: Calculate moles of CO2

Moles CO2 = mass CO2 / Molar mass CO2

Moles CO2 = 8.25 grams / 44.01 g/mol

Moles CO2 = 0.1875 moles

Step 4: Calculate moles of Helium

Moles Helium = total moles of gas - moles of CO2

Moles Helium = 0.447 - 0.1875 = 0.2595 moles of helium

Step 5: Calculate mass of helium

Mass of helium = moles of helium * molar mass of helium

Mass of helium = 0.2595 moles * 4 g/mol

Mass of helium = 1.038 grams

The gas mixture contains 1.038 grams of helium

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3 years ago

How many grams is 20 moles of (nh4)2so4 please show work

ryzh [129]

n=20 mol

(NH)4 SO4

Atomic masses :

N- 14

H- 1

S- 32

O- 16

Therefore M= 14×2 + 1×8 + 32 + 16×4

= 132

m= nM

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1 year ago

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Rom4ik [11]

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Then you add all of them together:

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Therefore, the molar weight of glucose is 180.15 grams.

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