Calculate 18.9 minus 2.15. Round the answer to the correct number of significant figures.

An interpenetrating primitive cubic structure like that of CsCl with anions in the corners has an edge length of 664 pm. If the

san4es73 [151]

Answer:

the ionic radius of the anion $r^- = 312.52 \ pm$

Explanation:

From the diagram shown below :

The anion $Cl^-$ is located at the corners

The cation $Cs^+$ is located at the body center

The Body diagonal length = $\sqrt{3 \ a }$

∴ $2 \ r^+ \ + 2r^- \ = \sqrt{3 \ a} \\ \\ r^+ +r^- = \frac{\sqrt{3}}{2} a$

Given that :

$\frac{r^+}{r^-} =0.84$ (i.e the ratio of the ionic radius of the cation to the ionic radius of

the anion )

$0.84r^- \ + r^- \ = \frac{\sqrt{3}}{2}a \\ \\ 1.84 r^- = \frac{3}{2}a \\ \\ r^- = \frac{\sqrt{3}}{2*1.84}a$

Also ; a = 664 pm

Then :

$r^- = \frac{\sqrt{3} }{2*1.84}*664 \ pm\\ \\ r^- = 312.52 \ pm$

Therefore, the ionic radius of the anion $r^- = 312.52 \ pm$

4 0

3 years ago

Only 20 plant species, such as rice, corn,and barely, make up the main sources of food for the entire human population.

riadik2000 [5.3K]

Answer:

I believe it would be D, to enhance the survival rate.

Explanation:

7 0

3 years ago

Read 2 more answers

A drop of water weighing 0.48 g is vaporized at 100 ?c and condenses on the surface of a 55-g block of aluminum that is initiall

irakobra [83]

<h3><u>Answer;</u></h3>

<em>-49 °C</em>

<h3><u>Explanation and solution;</u></h3>

Considering the fact that, the specific heat capacity of aluminum is 0.903 J/g x C, and the heat of vaporization of water at 25 C is 44.0 KJ/mol.

Moles water = 0.48 g / 18.02 g/mol

=0.0266 moles

<em>Heat lost by water</em> = 0.0266 mol x 44.0 kJ/mol

=1.17 kJ => 1170 J

<em>But heat lost =heat gained</em>

<em>Therefore;</em> Heat gained by aluminium = 1170 J

1170 = 55 x 0.903 ( T - 25) = 49.7 T - 1242

1170 + 1242 = 49.7 T

T = 48.5 °C ( 49 °C <em>at two significant figures)</em>

<em>Hence</em>, final temperature = 49 °C

4 0

3 years ago

Read 2 more answers

PLEASE HELP ME does a liquid have definite or indefinite shape.

andrezito [222]

Definite volume and indefinite shape

8 0

2 years ago

Traumatic acid contains 63.13% carbon, 8.830% hydrogen, and 28.03% oxygen. its molar mass is 228 g/mol. determine the empirical

Zina [86]

Q1)
firstly we need to determine the empirical formula of the compound. empirical formula is the simplest ratio of components in the compound.
percentages of the elements have been given, so lets assume we are calculating for a compound of 100g
C H O
mass 63.13 g 8.830 g 28.03 g
molar mass 12 g/mol 1 g/mol 16 g/mol
number of moles 63.13/12 8.830/1 28.03/16
5.26 8.830 1.75
divide by the smallest number of moles
5.26/1.75 8.830/1.75 1.75/1.75
= 3.01 = 5.04 =1
rounded off to the nearest whole numbers
C - 3
H - 5
O - 1
therefore empirical formula = C₃H₅O

Q2)
we have to next determine the molecular formula of the compound
molecular formula gives the actual composition of elements in the compound.
since we know the empirical formula and molecular mass, we can find how many empirical units are in the molecular formula.
mass of empirical unit = Cx3 + Hx5 + Ox1
= 12 g/mol x 3 + 1g/mol x 5 + 16 g/mol x 1
= 36 + 5 + 16 = 57 g/mol
the molecular mass = 228 g/mol
then number of empirical units in the molecular formula = 228 / 57 = 4
therefore there are 4 empirical units
then the molecular formula = 4 x empirical formula =4 (C₃H₅O)
molecular formula = C₁₂H₂₀O₄

3 0

3 years ago