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4 years ago

3. Which statement describes the charge and location of

Chemistry

1 answer:

nirvana33 [79]4 years ago

6 0

Answer:

C) An electron has a negative charge and is located outside the nucleus.

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What is the amount of energy for a photon that has a 125 cm wavelength

Lera25 [3.4K]

Answer:

1.59 x 10⁻²⁵ J.

Explanation:

The energy of a photon is calculated Planck - Einstein's equation:

E = h ν , where

E is the energy of the photon,

h is Planck's constant <em>(h = 6.626 x 10 ⁻³⁴ J.s)</em>

ν is the frequency of the photon

There is a relation between the frequency (ν ) and wave length (λ).

λ.ν = c,

where c is the speed of light in vacuum (c = 3 .0 x 10 ⁸ m/s).

λ = 125 cm = 1.25 m.

<em>Now, E = h.c/λ.</em>

∴ E = h.c/λ = (6.626 x 10 ⁻³⁴ J.s) (3 .0 x 10 ⁸ m/s) / (1.25 m) = 1.59 x 10⁻²⁵ J.

3 0

4 years ago

The element europium exists in nature as two isotopes: has a mass of u and has a mass of u. The average atomic mass of europium

ElenaW [278]

Answer:

Problem Details

The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu. Calculate the relative abundance of the two europium isotopes.

answer:

151Eu = 48%, 153Eu = 52%

4 0

3 years ago

Which substance can not be broken down by chemical means?

marissa [1.9K]

The substance that can not be broken down by chemical means is antimony.

8 0

3 years ago

The process by which hot and cold air are transferred in the atmosphere is what

xz_007 [3.2K]

t can be transferred from one region to the other. In solids heat is transferred by a process called conduction. In vacuum heat transfer is by a process called radiation. In fluids (gases and liquids) heat is transferred by a process known as convection.

7 0

3 years ago

6. The graph below shows the heating curve for ethanol (from –200C to 150C). Calculate the amount of heat (kJ) required for each

Kazeer [188]

This problem is providing the heating curve of ethanol showing relevant data such as the initial and final temperature, melting and boiling points, enthalpies of fusion and vaporization and specific heat of solid, liquid and gaseous ethanol, so that the overall heat is required and found to be 1.758 kJ according to:

<h3>Heating curves:</h3>

In chemistry, we widely use heating curves in order to figure out the required heat to take a substance from a temperature to another. This process may involve sensible heat and latent heat, when increasing or decreasing the temperature and changing the phase, respectively.

Thus, since ethanol starts off solid and end up being a vapor, we will find five types of heat, three of them related to the heating-up of ethanol, firstly solid, next liquid and then vapor, and the other two to its fusion and vaporization as shown below:

$Q_T=Q_1+Q_2+Q_3+Q_4+Q_5$

Hence, we begin by calculating each heat as follows, considering 1 g of ethanol is equivalent to 0.0217 mol:

$Q_1=0.0217mol*111.5\frac{J}{mol*\°C}[(-114.1\°C)-(-200\°C)] *\frac{1kJ}{1000J} =0.208kJ\\
\\
Q_2=0.0217mol*4.9\frac{kJ}{mol} =0.106kJ\\
\\
Q_3=0.0217mol*112.4\frac{J}{mol*\°C}[(78.4\°C)-(-114.1\°C)] *\frac{1kJ}{1000J} =0.470kJ\\
\\
Q_4=0.0217mol*38.6\frac{kJ}{mol} =0.838kJ\\
\\
Q_5=0.0217mol*87.5\frac{J}{mol*\°C}[(150\°C)-(78.4\°C)] *\frac{1kJ}{1000J} =0.136kJ$

Finally, we add them up to get the result:

$Q_T=0.208kJ+0.106kJ+0.470kJ+0.838kJ+0.136kJ\\
\\
Q_T=1.758kJ$

Learn more about heating curves: brainly.com/question/10481356

7 0

2 years ago