If a black hole is invisible how can we determine when one is present

Rhodium crystallizes in a face-centered cubic unit cell. The radius of a rhodium atom is 135 pm. Determine the density of rhodiu

Deffense [45]

Answer:

Density of unit cell ( rhodium) = 12.279 g/cm³

Explanation:

Given that:

The radius (r) of a rhodium atom = 135 pm

The atomic mass of rhodium = 102.90 amu

For a face-centered cubic unit cell,

$r = \dfrac{a}{2\sqrt{2}}$

where;

a = edge length.

Making "a" the subject of the formula:

$a = 2 \sqrt{2} \times r$

$a = 2 \times 1.414 \times 135 \ pm$

a = 381.8 pm

to cm, we get:

a = 381.8 × 10⁻¹⁰ cm

However, recall that:

$density \ of \ unit \ cell = \dfrac{mass \ of \ unit \ cell}{volume \ of \unit \ cell}$

where;

mass of unit cell = mass of atom × numbers of atoms per unit cell

Also;

$mass\ of\ atom =\dfrac{ atomic \ mass}{Avogadro \ number}$

$mass\ of\ atom =\dfrac{ 102.9}{6.023 \times 10^{23}}$

Recall also that number of atoms in a unit cell for a face-centered cubic = 4

So;

$mass \ of \ unit \ cell= \dfrac{102.90}{6.023 \times 10^{23}}\times 4$

mass of unit cell = 6.83380375 × 10⁻²² g

$Density \ of \ unit \ cell = \dfrac{6.83380375 \times 10^{-22}}{(381.8\times 10^{-10})^3}$

Density of unit cell ( rhodium) = 12.279 g/cm³

3 0

2 years ago

A volume of saline solution had a mass of 61.4 g at 4°C. An equal volume of water at the same

Maurinko [17]

Multiple by 2 because it was give u right answer

5 0

2 years ago

Complete the following precipitation reactions with balanced molecular, total ionic, and net ionic equations:

Dmitry [639]

Molecular equation

Hg₂(NO₃)₂ (aq) + KI(aq) ⇒Hg₂I₂(s) + 2KNO₃(aq)

Total Ionic equation

Hg²⁺(aq) + 2NO³⁻(aq) + 2K⁺aq) ⇒Hg₂I₂(s) + 2K⁺(aq) + NO³⁻ (aq)

Net Ionic equation

Hg²⁺(aq) + 2I⁻(aq) ⇒ Hg₂I₂(s)

<h3>What is the molecular equation?</h3>

Sometimes, a balanced equation is all that is used to refer to a chemical equation. Any ionic substances or acids are represented using their chemical formulas as neutral compounds in a molecular equation. Each substance's state is described in parenthesis after the formula. A complete ionic equation also contains the spectator ions, whereas a net ionic equation just displays the chemical species that are involved in a reaction.

The steps listed below can be used to determine the net ionic equation for a specific reaction:

Include the states of each chemical in the balanced molecular equation for the reaction.

To know more about the molecular equation, visit:

brainly.com/question/14286552

#SPJ4

4 0

1 year ago

Using the model of the Periodic Table, which two elements pictured have similar chemical properties?

liberstina [14]

Answer:

C) 1 and 3

Explanation:

A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. ... Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law.

5 0

3 years ago

Which of the following is an acceptable IUPAC name?(A) 3,6-dimethylheptane (B) 2-ethyl-3-methylheptane (C) 5-methyl-3-ethylhepta

bearhunter [10]

Answer:

D) 4-ethyl-4-methylheptane

Explanation:

The rules for naming of alkanes with substituents.

1. The carbon chain with the maximum number of carbon atoms must be selected as a parent chain.

2.Numbering should be done in such a way that each substituent gets the least number.

3. Substituents whose name comes before the another substituents's name in the English alphabet is written first.

4. Substituents are written first with their location in the chain and the name of the parent chain is done. Numbers are separated from numbers by comma and numbers are separated from letters by using hyphen.

Considering (a) 3,6-dimethylheptane

<u>Violation of Rule - 2 mentioned above</u>

The numbering of the parent chain is not done in a right way. Numbering must be done such that each substituent gets the least number. So, The correct name is 2,5-dimethylheptane

Considering (b) 2-ethyl-3-methylheptane

<u>Violation of Rule - 1 mentioned above.</u>

The carbon chain with the maximum number of carbon atoms must be selected as a parent chain. The parent chain selected is of 7 carbon atoms but the parent chain is of 8 carbon atoms. So, The correct name is 3,4-dimethyloctane

Considering (c) 5-methyl-3-ethylheptane

<u>Violation of Rule - 3 mentioned above.</u>

'e' comes before 'm' . So, ethyl- is written first than methyl- . So, The correct name is 3,6-dimethyloctane

Considering (d) 4-ethyl-4-methylheptane

<u>This is a IUPAC name and following all the rules mentioned above.</u>

3 0

3 years ago