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2 years ago

The speed of an electron is 1.68*10^8m/s what is the wavelength

Chemistry

1 answer:

ziro4ka [17]2 years ago

4 0

Answer:

$\lambda =4.33x10^{-12}m=4.33pm$

Explanation:

Hello there!

In this case, since the speed, wavelength and mass of an electron are related via the the Broglie wavelength:

$\lambda =\frac{h}{m*v}$

Thus, by plugging in the mass of the electron and the Planck's constant, we obtain the following wavelength:

$\lambda =\frac{6.626x10^{-34}J*s}{9.11x10^{-31}kg*1.68x10^{8}m/s}\\\\\lambda =4.33x10^{-12}m=4.33pm$

Best regards!

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A solid is crushed into a powder is chimacal change or pysical change

SSSSS [86.1K]

Answer:

Physical Change

Explanation:

A solid being crushed into a powder is a physical change because a chemical change is when substances combine to create new substances.

Hope this helps :)

4 0

2 years ago

Which element has the following Electron configuration? *

GuDViN [60]

Magnesium. You can count the electrons in each level and because the number of electrons is the same with protons you have the atomic number based of which you can get the element in the periodic table

3 0

2 years ago

Consider the balanced reaction

Scorpion4ik [409]

Answer:

561 g P₂O₃

Explanation:

To find the mass of P₂O₃, you need to (1) convert moles H₃PO₃ to moles P₂O₃ (via mole-to-mole ratio from equation coefficients) and then (2) convert moles P₂O₃ to grams P₂O₃ (via molar mass). It is important to arrange the ratios/conversions in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the amount of sig figs in the given value.

Atomic Mass (P): 30.974 g/mol

Atomic Mass (O): 15.998 g/mol

Molar Mass (P₂O₃): 2(30.974 g/mol) + 3(15.998 g/mol)

Molar Mass (P₂O₃): 109.942 g/mol

1 P₂O₃ + 3 H₂O -----> 2 H₃PO₃

10.2 moles H₃PO₃ 1 mole P₂O₃ 109.942 g
---------------------------- x -------------------------- x ------------------- = 561 g P₂O₃
2 moles H₃PO₃ 1 mole

6 0

1 year ago

A certain radioactive isotope decays at a rate of 0.2% annually. Determine the half-life of this isotope, to the nearest year

pychu [463]

Answer:

The half-life of the radioactive isotope is 346 years.

Explanation:

The decay rate of the isotope is modelled after the following first-order linear ordinary differential equation:

$\frac{dm}{dt} = -\frac{m}{\tau}$

Where:

$m$ - Current isotope mass, measured in kilograms.

$t$ - Time, measured in years.

$\tau$ - Time constant, measured in years.

The solution of this differential equation is:

$m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }$

Where $m_{o}$ is the initial mass of the isotope. It is known that radioactive isotope decays at a yearly rate of 0.2 % annually, then, the following relationship is obtained:

$\%e = \frac{m(t)-m(t+1)}{m(t)}\times 100\,\% = 0.2\,\%$

$1 - \frac{m(t+1)}{m(t)} = 0.002$

$1 - \frac{m_{o}\cdot e^{-\frac{t+1}{\tau} }}{m_{o}\cdot e^{-\frac{t}{\tau} }}=0.002$

$1 - e^{-\frac{1}{\tau} } = 0.002$

$e^{-\frac{1}{\tau} } = 0.998$

$-\frac{1}{\tau} = \ln 0.998$

The time constant associated to the decay is:

$\tau = -\frac{1}{\ln 0.998}$

$\tau \approx 499.500\,years$

Finally, the half-life of the isotope as a function of time constant is given by the expression described below:

$t_{1/2} = \tau \cdot \ln 2$

If $\tau \approx 499.500\,years$ , the half-life of the isotope is:

$t_{1/2} = (499.500\,years)\cdot \ln 2$

$t_{1/2}\approx 346.227\,years$

The half-life of the radioactive isotope is 346 years.

6 0

2 years ago

Determine the formula of chromic acid.

Katyanochek1 [597]

<u>Answer:</u> The formula of chromic acid is $H_2CrO_4$

<u>Explanation:</u>

We are given an ionic compound named as chromic acid. This acid is formed by the combination of hydrogen ion and chromate ion.

An acid is defined as the substance which releases hydrogen ion when dissolved in water.

Hydrogen is the 1st element of periodic table having electronic configuration of $1s^1$ .

This element will loose 1 electron to form $H^{+}$ ion.

Chromate ion is a polyatomic ion having chemical formula of $CrO_4^{2-}$

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

So, the chemical formula for the given compound is $H_2CrO_4$

Thus, the formula of chromic acid is $H_2CrO_4$

8 0

3 years ago