All organic compounds contain ______, hydrogen, and usually oxygen. nitrogen. phosphorus. sulfur carbon.

The radioactive isotope of lead, Pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.

Marina86 [1]

Answer:

Therefore it will take 7.66 hours for 80% of the lead decay.

Explanation:

The differential equation for decay is

$\frac{dA}{dt}= kA$

$\Rightarrow \frac{dA}{A}=kdt$

Integrating both sides

ln A= kt+c₁

$\Rightarrow A= e^{kt+c_1}$

$\Rightarrow A=Ce^{kt}$ [ $e^{c_1}=C$ ]

The initial condition is A(0)= A₀,

$\therefore A_0=Ce^{0.k}$

$\Rightarrow C=A_0$

$\therefore A=A_0e^{kt}$ .........(1)

Given that the $Pb_{209}$ has half life of 3.3 hours.

For half life $A=\frac12 A_0$ putting this in equation (1)

$\frac12A_0=A_0e^{k\times3.3}$

$\Rightarrow ln(\frac12)= 3.3k$ [taking ln both sides, $ln \ e^a=a$ ]

$\Rightarrow k=\frac{ln \frac12}{3.3}$

⇒k= - 0.21

Now A₀= 1 gram, 80%=0.8

and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram

Now putting the value of k,A and A₀in the equation (1)

$\therefore 0.2=1e^{(-0.21)\times t}$

$\Rightarrow e^{-0.21t}=0.2$

$\Rightarrow -0.21t= ln(0. 2)$

$\Rightarrow t= \frac{ln (0.2)}{-0.21}$

⇒ t≈7.66

Therefore it will take 7.66 hours for 80% of the lead decay.

3 0

3 years ago

What would cause the pressure of a gas to increase?

IrinaK [193]

Answer: The pressure of a gas will increase when there is a decrease in the volume of the gas.

Explanation: according to Boyle's law, the volume of a gas will decrease when the pressure is increased at constant temperature and vice versa.

8 0

3 years ago

The sp of pbbr2 is 6. 60×10−6. what is the molar solubility of pbbr2 in pure water?

Inessa05 [86]

Ksp of PbBr₂ is 6.60 × 10⁻⁶. The molar solubility of PbBr₂ in pure water is 0.0118M.

Ksp or Solubility Product Constant is an equilibrium constant for the dissociation in an aqueous solution.

Molar solubility (S) is the concentration of the dissolved substance in a solution that is saturated.

Let the molar solubility be S upon dissociation.

PbBr₂ or Lead Bromide dissociates in pure water as follows:

PbBr₂ ----------> Pb⁺² + Br⁻

S 2S

Ksp = [Pb⁺²] [ Br⁻]

Ksp = (S) (2S)²

Ksp = 4S³

6.60 × 10⁻⁶ = 4S³

S = 0.0118M

Hence, the Molar solubility S is 0.0118M.

Learn more about Molar solubility here, brainly.com/question/16243859

#SPJ4

6 0

2 years ago

PLEASE HELP ME!!! ASAP

shtirl [24]

Answer:

Theoretical yield of the reaction = 34 g

Excess reactant is hydrogen

Limiting reactant is nitrogen

Explanation:

Given there is 100 g of nitrogen and 100 g of hydrogen

Number of moles of nitrogen = 100 ÷ 28 = 3·57

Number of moles of hydrogen = 100 ÷ 2 = 50

Reaction between nitrogen and hydrogen yields ammonia according to the following chemical equation

N2 + 3H2 → 2NH3

From the above chemical equation for every mole of nitrogen that reacts, 3 moles of hydrogen will be required and 2 moles of ammonia will be formed

Now we have 3·57 moles of nitrogen and therefore we require 3 × 3·57 moles of hydrogen

⇒ We require 10·71 moles of hydrogen

But we have 50 moles of hydrogen

∴ Limiting reactant is nitrogen and excess reactant is hydrogen

From the balanced chemical equation the yield will be 2 × 3·57 moles of ammonia

Molecular weight of ammonia = 17 g

∴ Theoretical yield of the reaction = 2 × 3·57 × 17 = 121·38 g

5 0

4 years ago

Please help me on this I’ll give 30 points

Rufina [12.5K]

Answer:

1. 10.66 moles of Al

2. 2.5 moles of Al₂O₃

3. 143.87 g of SO₂

Explanation:

The balance chemical equation is as follow,

4 Al + 3 O₂ → 2 Al₂O₃

According to balance chemical equation,

3 moles of O₂ required = 4 moles of Al

So,

8 moles of O₂ will require = X moles of Al

Solving for X,

X = 8 mol × 4 mol / 3 mol

X = 10.66 moles of Al

According to balance chemical equation,

4 moles of Al produced = 2 moles of Al₂O₃

So,

5 moles of Al will produce = X moles of Al₂O₃

Solving for X,

X = 5 mol × 2 mol / 4 mol

X = 2.5 moles of Al₂O₃

The balance chemical equation for the oxidation of carbon disulfide is as follow;

CS₂ + 3 O₂ → CO₂ + 2 SO₂

Step 1: <u>Calculate Moles of CS₂ as;</u>

Moles = Mass / M.Mass

Moles = 85.5 g / 76.14 g/mol

Moles = 1.12 moles of CS₂

Step 2: <u>Find out moles of SO₂ as;</u>

According to balance chemical equation,

1 mole of CS₂ produced = 2 moles of SO₂

So,

1.12 moles of CS₂ will produce = X moles of SO₂

Solving for X,

X = 1.12 mol × 2 mol / 1 mol

X = 2.24 moles of SO₂

Step 3: <u>Calculate Mass of SO₂ as;</u>

Mass = Moles × M.Mass

Mass = 2.24 mol × 64.06 g/mol

Mass = 143.87 g of SO₂

4 0

3 years ago