Express the following in

An ostrich runs north in a straight line for 21 meters. She then turns around and runs 25 meters back toward her nest (south) on

drek231 [11]

The ostrich runs 21 N then goes back by 25 S

The displacement is -4 S

21 - 25 = -4

6 0

3 years ago

Which is one way that Dalton's atomic theory has been shown to be incorrect?

KATRIN_1 [288]

The answer is D. His belief is was that atoms could not be split. That is what was disproved really fast ;)

6 0

3 years ago

Calculate the electrical energy per gram of anode material for the following reaction at 298 K:

solmaris [256]

43.8 kJ

<h3>Explanation</h3>

There are two electrodes in a voltaic cell. Which one is the anode?

The lithium atom used to have no oxygen atoms when it was on the reactant side. It gains two oxygen atoms after the reaction. It has gained more oxygen atoms than the manganese atom. Gaining oxygen is oxidation. As a result, lithium is being oxidized.

Oxidation takes place at the anode of a cell. Therefore, the anode of this cell is made of lithium.

Lithium has an atomic mass of 6.94. Each gram of Li would contain 1/6.94 = 0.144 moles of Li atoms. Each Li atom loses one electron in this cell. Therefore, the number of electron transferred, n, equals 0.144 moles for each gram of the anode.

Let $w_\text{max}$ represents the electrical energy produced.

$w_\text{max} = n \cdot F \cdot E_\text{cell}$ , where

n is the number of moles electrons transferred,
F is the Faraday's constant,
E $_\text{cell}$ is the cell potential,

n = 0.144 mol, as shown above, and

F = 96.486 kJ / ( $\text{V} \cdot \text{mol} \; \text{e}^{-}$ ).

Therefore,

$w_\text{max} = n \cdot F \cdot E\\\phantom{w_\text{max}} = 0.144 \times 96.486 \times 3.15 \\\phantom{w_\text{max}} = 43.8 \; \text{kJ}$ .

3 0

3 years ago

The energy E of the electron in a hydrogen atom can be calculated from the Bohr formula: E = R_y/n^2 In this equation R_y stands

Katarina [22]

Answer:

The wavelength of the line in the emission line spectrum of hydrogen caused by the transition of the electron for the given energy levels is $5.23\times 10^{-5} m$

Explanation:

Given :

The energy E of the electron in a hydrogen atom can be calculated from the Bohr formula:

$E=\frac{R_y}{n^2}$

$R_y=2.18\times 10^{-18} J$ = Rydberg energy

n = principal quantum number of the orbital

Energy of 11th orbit = $E_{11}$

$E_{11}=\frac{2.18\times 10^{-18} J}{11^2}=1.80\times 10^{-20} J$

Energy of 10th orbit = $E_{10}$

$E_{10}=\frac{2.18\times 10^{-18} J}{10^2}=2.18\times 10^{-20} J$

Energy difference between both the levels will corresponds to the energy of the wavelength of the line which can be calculated by using Planck's equation.

$E'=E_{10}-E_{11}=2.18\times 10^{-20} J-1.80\times 10^{-20} J$

$=E'=0.38\times 10^{-20} J$

$\lambda =\frac{hc}{E'}$ (Planck's' equation)

$\lambda = \frac{6.626\times 10^{-34} Js\times 3\times 10^8 m/s}{0.38\times 10^{-20} J}$

$\lambda = 5.2310\times 10^{-5} m\approx 5.23\times 10^{-5} m$

The wavelength of the line in the emission line spectrum of hydrogen caused by the transition of the electron for the given energy levels is $5.23\times 10^{-5} m$

3 0

3 years ago

Ionic compounds involve a (share, tranfer) of electrons and typically involve atoms that have (Large, similar, very different) e

Juliette [100K]

Answer:

2 Transfer; very different

Explanation:

Ionic compound are compound that are formed from transfer of electron. The cations donate the electron(s) while the anion receive the electron(s). The compound possess a positively charged end and a negatively charge end. Example of ionic compound is NaCl . The sodium donates one electron to the chlorine to fulfill the octet rule. The sodium atom becomes positively charged as it donate electron to the chlorine atom. The chlorine atom becomes negatively charged as it receive electron from Sodium atom.

The atoms that are involve in forming ionic compound have very different electronegativity . Electronegativity is the measure of the ability of an atom to attract a bond pair of electron. For example the NaCl compound, the two atom has verse differences in the electronegativity. Cl atom is far more electronegative than Sodium atom.

6 0

3 years ago