Please help me with these I'll give 15 points

A white coloured solid salt “A” on heating gives out two colourless gases “B” and “C”.

QveST [7]

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6 0

3 years ago

Potassium-40 is a radioactive isotope that decays into a single argon-40 atom and other particles with a half-life of 1:25 billi

stiks02 [169]

Answer:

0.147 billion years = 147.35 million years.

Explanation:

It is known that the decay of a radioactive isotope isotope obeys first order kinetics.

Half-life time is the time needed for the reactants to be in its half concentration.

If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).

Also, it is clear that in first order decay the half-life time is independent of the initial concentration.

The half-life of Potassium-40 is 1.25 billion years.

For, first order reactions:

k = ln(2)/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life of the reaction.

∴ k =0.693/(t1/2) = 0.693/(1.25 billion years) = 0.8 billion year⁻¹.

Also, we have the integral law of first order reaction:

kt = ln([A₀]/[A]),

where, k is the rate constant of the reaction (k = 0.8 billion year⁻¹).

t is the time of the reaction (t = ??? year).

[A₀] is the initial concentration of (Potassium-40) ([A₀] = 100%).

[A] is the remaining concentration of (Potassium-40) ([A] = 88.88%).

At the time needed to be determined:

8 times as many potassium-40 atoms as argon-40 atoms. Assume the argon-40 only comes from radioactive decay.

If we start with 100% Potassium-40:

∴ The remaining concentration of Potassium-40 ([A] = 88.88%).

and that of argon-40 produced from potassium-40 decayed = 11.11%.

That the ratio of (remaining Potassium-40) to (argon-40 produced from potassium-40 decayed) is (8: 1).

∴ t = (1/k) ln([A₀]/[A]) = (1/0.8 billion year⁻¹) ln(100%/88.88%) = 0.147 billion years = 147.35 million years.

8 0

3 years ago

Find the mass of carbon in a sample of hcn with a mass of 3.37 g

dsp73

Answer:

我實際

Explanation:

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7 0

3 years ago

At a wastewater treatment plant, FeCl3(s) is added to remove excess phosphate from the effluent. Assume the following reactions

RoseWind [281]

Answer : The concentration of $Fe^{3+}$ needed is, $2.37\times 10^4M$

Explanation :

First we have to calculate the mole of phosphate.

As we are given that, 1 mg P/L that means, 1 mg of phosphate present in 1 L of solution.

$\text{Moles of phosphate}=\frac{\text{Mass of phosphate}}{\text{Molar mass of phosphate}}$

Molar mass of phosphate = 94.97 g/mole

$\text{Moles of phosphate}=\frac{1mg}{94.97g/mol}=\frac{0.001g}{94.97g/mol}=1.053\times 10^{-5}mol$

Now we have to calculate the concentration of phosphate.

$\text{Concentration of phosphate}=\frac{\text{Moles of phosphate}}{\text{Volume of solution}}$

$\text{Concentration of phosphate}=\frac{1.053\times 10^{-5}mol}{1L}=1.053\times 10^{-5}mol/L$

Now we have to calculate the concentration of $Fe^{3+}$ .

The second equilibrium reaction is,

$FePO_4\rightleftharpoons Fe^{3+}+PO_4^{3-}$

The solubility constant expression for this reaction is:

$K_{sp}=[Fe^{3+}][PO_4^{3-}]$

Given: $K_{sp}=\frac{1}{4}$

$\frac{1}{4}=[Fe^{3+}]\times 1.053\times 10^{-5}mol/L$

$[Fe^{3+}]=2.37\times 10^4M$

Thus, the concentration of $Fe^{3+}$ needed is, $2.37\times 10^4M$

8 0

4 years ago

How does hydrogen peroxide bleach hair?

harkovskaia [24]

How does hydrogen peroxide bleach hair? THe h202 molecule sbreak the double bonds in pigment molecules

Question 3

What advantage does hydrogen peroxide have over other bleaching agents such as chlorine gas? Hydrogen peroxide decomposes into nontoxic water and oxygen.

Question 4

How does hydrogen peroxide play a role in air pollution?Peroxide fragments react with unburned fuel creating eye irritants.

Question 5

In the reaction between melanin and hydrogen peroxide, which substance is oxidized (receives electrons)? melanin is oxidized,hydrogen peroxide is reduced

8 0

4 years ago