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3 years ago

What element is used as a shield to protect from radioactive substances?

Chemistry

1 answer:

Dmitrij [34]3 years ago

7 0

Answer: lead

Lead has been used for gamma radiation shielding since the discovery of radioactive material & x-ray.

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Using the information in the table, calculate the number of moles in a \pu{7.89 kg}7.89 kg7, point, 89, space, k, g sample of as

Karolina [17]

We have to find the number of moles in a 7.89 kg sample of aspirin.

The formula of aspirin is: C₉H₈O₄

We are given the molar mass of C, H and O:

H: 1.008 g/mol C: 12.01 g/mol O: 16.00 g/mol

Since one molecule of aspirin has 9 atoms of C, 8 atoms of H and 4 atoms of O, and using the molar masses given, we can calculate the molar mass of aspirin:

molar mass of aspirin = 9 * 12.01 g/mol + 8 * 1.008 g/mol + 4 * 16.00 g/mol

molar mass of aspirin = 180.154 g/mol

Before we find the number of moles we can convert 7.89 kg to g. Since we know that there are 1000 g in 1 kg, we can convert it like this:

1000 g = 1 kg

mass of sample = 7.89 kg * 1000 g/1 kg

mass of sample = 7890 g

Finally, we can find the number of moles in the sample using the molar mass.

number of moles = 7890 g * 1 mol/180.154 g

number of moles = 43.795 moles

Answer: The number of moles in the sample is 43.8 moles (using 3 SF)

7 0

1 year ago

Plz help ASAP it’s dude soon

Alex_Xolod [135]

Answer:

Explanation:

6 0

2 years ago

Acetylene (C2H2), an important fuel in welding, is produced in the laboratory when calcium carbide (CaC2) reacts with water: CaC

Anastaziya [24]

Answer:

There are 1.287 grams of acetylene collected

Explanation:

Total gas pressure = 909 mmHg

Vapor pressure of water = 20.7 mmHg

Pressure of acetylene = 909 mmHg - 20.7 mmHg = 888.3 mmHg

1mmHg = 1 torr

22 ° C + 273.15 = 295.15 Kelvin

Ideal gas law ⇒ pV = nRT

⇒ with p = pressure of the gas in atm

⇒ with V = volume of the gas in L

⇒ with n = amount of substance of gas ( in moles)

⇒ with R = gas constant, equal to the product of the Boltzmann constant and the Avogadro constant (62.36 L * Torr *K^−1 *mol^−1)

⇒ with T = absolute temperature of the gas (in Kelvin)

888.3 torr * 1.024 L = n * 62.36 L * Torr *K^−1 *mol^−1 * 295.15 K

n = 0.04942 moles of C2H2

Mass of C2H2 = 0.04942 moles x 26.04 g/mole = 1.287 g

There are 1.287 grams of acetylene collected

6 0

2 years ago

Question 2 (0 points)

bazaltina [42]

Answer:

The probability of spinning red with the spinner or rolling an odd number with the die is $\dfrac{1}{8}$

Explanation:

Given that,

Total color in spinner = 4

Let the area of four parts is equal in the spinner.

We need to calculate the probability of spinning red

Using formula of probability

$P(A) = \dfrac{Number\ of\ red\ color\ outcome}{Total\ number\ of\ colors\ in\ the\ spinner}$

Put the value into the formula

$P(A)=\dfrac{1}{4}$

We need to calculate the probability of odd number of the die

Using formula of probability

$P(B) = \dfrac{Number\ of\ odd\ digits\ outcome}{Total\ number\ of\ digits\ in\ the\ die}$

Put the value into the formula

$P(B)=\dfrac{3}{6}$

$P(B)=\dfrac{1}{2}$

We need to calculate the probability of spinning red with the spinner or rolling an odd number with the die

Using formula of probability of two events which is independent

$P(A\ and\ B)=P(A)\times P(B)$

Put the value into the formula

$P(A\ and\ B)=\dfrac{1}{4}\times\dfrac{1}{2}$

$P(A\ and\ B)=\dfrac{1}{8}$

Hence, The probability of spinning red with the spinner or rolling an odd number with the die is $\dfrac{1}{8}$

5 0

3 years ago

What is the hydrogen ion (H+) concentration of a solution of pH 8?

fgiga [73]

Answer:

10−8 M.

Explanation:

In this problem we are given pH and asked to solve for the hydrogen ion concentration. Using the equation, pH = − log [H+] , we can solve for [H+] as,

− pH = log [H+] ,

[H+] = 10−pH,

by exponentiating both sides with base 10 to "undo" the common logarithm. The hydrogen ion concentration of blood with pH 7.4 is,

[H+] = 10−7.4 ≈ 0.0000040 = 4.0 × In this problem we are given pH and asked to solve for the hydrogen ion concentration. Using the equation, pH = − log [H+] , we can solve for [H+] as,

− pH = log [H+] ,

[H+] = 10−pH,

by exponentiating both sides with base 10 to "undo" the common logarithm. The hydrogen ion concentration of blood with pH 7.4 is,

[H+] = 10−7.4 ≈ 0.0000040 = 4.0 × 10−8 M.

3 0

3 years ago

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