# the reaction A->B is second order in A and the rate constant is 0.039L/mol s. if it took 23 sec for the concentration of A to decrease to 0.30 M, what was the starting concentration of A

0.41 M

Explanation:

A -> B

rate constant (k) = 0.039L/mol s

t = 23

Final concentration, [A]  = 0.30M

Initial concentration, [A]o = x

1 / [A]  = kt + 1 / [A]o

1 / [A]o = 1 / [A] - kt

1 / [A]o  = 1 / 0.30   - 0.039 (23)

1 / [A]  = 3.33 -  0.897 = 2.433

[A] = 0.41 M

## Related Questions

I belive the answer is A but the image quality is hard to tell.

Explanation:

As pressure increases the higher the melting point of rock becomes making it harder to melt, thats why molten rocks brought to the surface melt because of the change in pressure.

The Aurora Borealis or northern light occur when solar flares react with the atmosphere near the north poles. The Aurora give off colred light because electricity is flowing. Which state of matter must the air be in for the Aurora to occur? A) gas B) liquid C) plasma D) solid

Natural phenomena characterized by colored lights in the sky, is caused by the interaction of charged particles of energy from the solar wind with the magnetic layer of the earth so we have turbulence and multicolored plasma clouds known as auroras arise.

C) plasma

Explanation:

Plasma is the state where electrons are stripped allow these gases to conduct electricity.

How many oxygen molecules in 2.3x10-⁸g of molecular oxygen ​

6.321 × 10^22

Explanation:

Mass of Oxygen =

3.36

g

Molar mass of oxygen (

O

2

) = 16 x 2 =

32

g

m

o

l

Total molecules in oxygen = Mass in grams/Molar mass x

N

A

=

3.36

32

x

6.02

x

10

23

=

6.321

x

10

22

Note:

N

A

6.02

x

10

23

Hope it helps...

Many calculators use photocells to provide their energy. Find the maximum wavelength needed to remove an electron from silver (Φ = 7.59 x 10⁻¹⁹ J). Is silver a good choice for a photocell that uses visible light?

= 261 nm

Silver is not a good choice.

Explanation:

Where,

h is Plank's constant having value

c is the speed of light having value

is the wavelength of the light

Given that:- Energy =

= 261 nm

Visible range has a spectrum of 380 to 740 nm

So, Silver is not a good choice.

The maximum wavelength needed to remove an electron from silver is approximately 262 nm. Silver is not a good choice for a photocell that uses visible light.

### Explanation:

To find the maximum wavelength needed to remove an electron from silver, we can use the work function of silver, which is Φ = 4.73 eV. The threshold wavelength for observing the photoelectric effect in silver can be calculated using Equation 6.16, which is λ = hc/Φ. Substituting the given values, we have λ = (1240 eV⋅nm) / (4.73 eV), which gives us a threshold wavelength of approximately 262 nm. Since visible light ranges from 400 to 700 nm, silver is not a good choice for a photocell that uses visible light.

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What is the change in electrons for nitrogen in the following reaction?S + NO3 - -> SO2 + NO

A. Gain 2 electrons
B. Gain 3 electrons
C. Lose 2 electrons
D. Lose 3 electrons

Nitrogen changes from +5 in - to +2 in NO. This means nitrogen has gained 3 electrons. Option B

To determine the change in electrons for nitrogen in the given reaction, we need to compare the oxidation state of nitrogen in the reactant (-) and the product (NO).

In the reactant, -, nitrogen is in the +5 oxidation state. This is because oxygen has an oxidation state of -2, and there are three oxygen atoms in -. Therefore, nitrogen must have an oxidation state of +5 to balance the overall charge of -.

In the product, NO, nitrogen is in the +2 oxidation state. This is because oxygen has an oxidation state of -2, and there is only one oxygen atom in NO. Therefore, nitrogen must have an oxidation state of +2 to balance the overall charge of NO.

By comparing the oxidation states of nitrogen in the reactant and the product, we can determine the change in electrons. The change in oxidation state corresponds to the change in the number of electrons gained or lost by the nitrogen atom.

In this case, nitrogen changes from +5 in - to +2 in NO. This means nitrogen has gained 3 electrons.

Therefore, the correct answer is B) Gain 3 electrons.

The nitrogen atom undergoes a reduction because it gains electrons, reducing its oxidation state from +5 to +2 in the reaction.

Option B

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An element x is found to have a mass number of 31 and atomic number of 17. idenrify the group and the period to which it belongs?