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2 years ago

An isotope with a half life of 10 min and a starting sample size of 100 g would have

Chemistry

1 answer:

IgorC [24]2 years ago

7 0

Answer:

12.5 gm left

Explanation:

30 minutes is THREE half lives

1/2^3 = 1/8th would be left

100g * 1/8 = 12.5 gm

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(LO 37,45) A reaction is 75% complete in 45.0 min. How long after its start will the reaction be 50% complete if it is (A) first

seropon [69]

Answer:

A) t = 22.5 min and B) t = 29.94 min

Explanation:

Initial concentration, [A]₀ = 100

Final concentration = 100 -75 = 25

Time = 45 min

A) First order reaction

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[25] − ln[100] = - 45k

-1.386 = -45k

k = 0.0308 min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[50] − ln[100] = - 0.0308 * t

-0.693 = -0.0308 * t

t = 22.5 min

B) Zero Order

[A] = [A]₀ − kt

Using the values from the initial reaction and solving for k, we have;

25 = 100 - k(45)

-75 = -45k

k = 1.67 M min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

[A] = [A]₀ − kt

50 = 100 - (1.67)t

-50 = - 1.67t

t = 29.94 min

3 0

3 years ago

How did Bohr solve the contradiction with physics with his model of an atom

daser333 [38]

Answer:

He used Velocity and Radius.

Explanation:

The uncertainty truths contradicts Bohr's thoughts of electrons.

4 0

3 years ago

a sample of 3.00 g of so2 (g)originally in a 5.00 L vesselat 21 degee Celsius is transferred to a 10.0 L vessel at 26 degree Cel

eimsori [14]

Answer:

1) The partial pressure of SO₂ gas in the larger container = 0.115 atm.

2) The partial pressure of N₂ gas in the larger container = 0.206 atm.

3) The total pressure in the vessel = 0.321 atm.

Explanation:

To calculate the partial pressure of each gas, we can use the general law of ideal gas: PV = nRT.

where, P is the partial pressure of the gas in atm,

V is the volume of the vessel in L,

n is the no. of moles of the gas,

R is the general gas constant (R = 0.082 L.atm/mol.K),

T is the temperature of the gas in K.

1) What is the partial pressure of SO₂ gas in the larger container?

∵ P = nRT/V.

n = mass/molar mass = (3.0 g)/(64.066 g/mol) = 0.047 mol.

R = 0.082 L.atm/mol.K.

T = 26 °C + 273.15 = 299.15 K.

V = 10.0 L. (The volume of the new container)

∴ P = nRT/V = (0.047 mol)(0.082 L.atm/mol.K)(299.15 K)/(10.0 L) = 0.115 atm.

2) What is the partial pressure of N₂ gas in the larger container?

∵ P = nRT/V.

n = mass/molar mass = (2.35 g)/(28.0 g/mol) = 0.084 mol.

R = 0.082 L.atm/mol.K.

T = 26 °C + 273.15 = 299.15 K.

V = 10.0 L. (The volume of the new container)

∴ P = nRT/V = (0.084 mol)(0.082 L.atm/mol.K)(299.15 K)/(10.0 L) = 0.206 atm.

3) What is the total pressure in the vessel?

According to Dalton's law the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

∵ The total pressure in the vessel = the partial pressure of SO₂ + the partial pressure of N₂.

∴ The total pressure in the vessel = 0.115 + 0.206 = 0.321 atm.

5 0

3 years ago

A 25.00 g solid sample of Ca(OH)2 was added into 1250 mL of 0.400 M HCl aqueous solution. The temperature of the solution was de

daser333 [38]

Answer:

86.735 kJ

Explanation:

Simply multiply the change in temperature by the Ccal;

(36.6 - 20.0)×5.225 = 86.735

5 0

3 years ago

How do the solvent and solute differ in a solution

hodyreva [135]

A solution is a homogeneous mixture, meaning it contains 2 or more substances. A solute is a substance that’s dissolved in the solvent. Think of it as dissolving salt (solute) in water (solvent) to make a salt solution. The amount of each substance in the solution impacts the concentration of it. So if I put more salt than water, it increases its concentration, while adding more water decreases its concentration.

7 0

3 years ago