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3 years ago

13

Provide the mass number of Fe, which has 29 neutrons

1 answer:

zmey [24]3 years ago

6 0

Answer:

55.845 u

Explanation:

Fe, iron, has 29 neutrons and a atomic mass of 55.845 u

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D) light is reflecting in the direction indicated by T.

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When the concentration of A in the reaction A ..... B was changed from 1.20 M to 0.60 M, the half-life increased from 2.0 min to

Reika [66]

Answer:

2

$0.4167\ \text{M}^{-1}\text{min}^{-1}$

Explanation:

Half-life

${t_{1/2}}A=2\ \text{min}$

${t_{1/2}}B=4\ \text{min}$

Concentration

${[A]_0}_A=1.2\ \text{M}$

${[A]_0}_B=0.6\ \text{M}$

We have the relation

$t_{1/2}\propto \dfrac{1}{[A]_0^{n-1}}$

So

$\dfrac{{t_{1/2}}_A}{{t_{1/2}}_B}=\left(\dfrac{{[A]_0}_B}{{[A]_0}_A}\right)^{n-1}\\\Rightarrow \dfrac{2}{4}=\left(\dfrac{0.6}{1.2}\right)^{n-1}\\\Rightarrow \dfrac{1}{2}=\left(\dfrac{1}{2}\right)^{n-1}$

Comparing the exponents we get

$1=n-1\\\Rightarrow n=2$

The order of the reaction is 2.

$t_{1/2}=\dfrac{1}{k[A]_0^{n-1}}\\\Rightarrow k=\dfrac{1}{t_{1/2}[A]_0^{n-1}}\\\Rightarrow k=\dfrac{1}{2\times 1.2^{2-1}}\\\Rightarrow k=0.4167\ \text{M}^{-1}\text{min}^{-1}$

The rate constant is $0.4167\ \text{M}^{-1}\text{min}^{-1}$

3 0

3 years ago

The absorbance of an equilibrium mixture containing FeSCN2 was measured at 447 nm and found to be 0.347. What is the equilibrium

Ksenya-84 [330]

Answer:

The concentration is $C = 1.11 mol/L$

Explanation:

From the question we are told that

The absorbance is $A = 0.347$

The length is $l = 447 nm = 447 *10^{-7} \ cm$

Generally absorbance is mathematically represented as

$A = \epsilon* C * l$

where $\epsilon$ is the molar absorptivity of FeSCN2 with a value $\epsilon = 7.0*10^3 L/cm/mol$

and $C$ is the equilibrium concentration of FeSCN2

So

$C = \frac{A}{\epsilon * l }$

substituting values

$C = \frac{0.347}{7.0*10^{3} * 447 *10^{-7} }$

$C = 1.11 mol/L$

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A mixture of pepper and water is a suspension because ________ HELPPPP

malfutka [58]

It doesn't because pepper does not dissolve

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Menthol (FW = 156.3 g/mol), the strong-smelling substance in many cough drops, is a compound of carbon, hydrogen, and oxygen. Wh

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Answer: the molecular formula is C10H20O

Explanation:Please see attachment for explanation

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