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In solid NaCl, the equilibrium separation between neighboring Na+ and Cl- ions is 0.283 nm. Calculate the coulombic energy betwe

const2013 [10]

Explanation:

It is given that r = 0.283 nm. As 1 nm = $10^{-9} m$ .

Hence, 0.283 nm = $0.283 \times 10^{-9} m$

Formula for coulombic energy is as follows.

$U_{coulomb} = -1.748 \frac{e^{2}}{4 \pi \epsilon_{o} r}$

where, e = $1.6 \times 10^{-19}$ C

$\epsilon_{o}$ = $8.85 \times 10^{-12}$

$U_{coulomb} = -1.748 \frac{(1.6 \times 10^{-19}^{2}}{4 \times 3.14 \times 8.85 \times 10^{-12} \times 0.283 \times 10^{-9}}$

= $1.423 \times 10^{-18} J$

As 1 eV = $1.6 \times 10^{-19} J$

So, 1 J = $\frac{1 eV}{1.6 \times 10^{-19}}$

Hence, U = $\frac{1.423 \times 10^{-18} J}{1.6 \times 10^{-19} J}$

= 8.9 eV

Also, 1 J = $\frac{10^{-3} kJ}{6.022 \times 10^{23}mol}$

= $1.67 \times 10^{-27}$ kJ/mol

Therefore, U = $1.423 \times 10^{-18} J \times 1.67 \times 10^{-27}$ kJ/mol

= $2.37 \times 10^{-45} kJ/mol$

7 0

2 years ago

Arbon dioxide is dissolved in blood (ph 7.5) to form a mixture of carbonic acid and bicarbonate. Part a neglecting free co2, wha

Aleks04 [339]

Answer : The fraction of carbonic acid present in the blood is 5.95%

Explanation :

The mixture consists of carbonic acid ( H₂CO₃) and bicarbonate ion ( HCO₃⁻). This represents a mixture of weak acid and its conjugate which is a buffer.

The pH of a buffer is calculated using Henderson equation which is given below.

$pH = pKa + log \frac{[Base]}{[Acid]}$

We have been given,

pH = 7.5

pKa of carbonic acid = 6.3

Let us plug in the values in Henderson equation to find the ratio Base/Acid.

$7.5 = 6.3 + log \frac{[base]}{[acid]}$

$1.2 = log \frac{[base]}{[acid]}$

$\frac{[Base]}{[Acid]} = 10^{1.2}$

$\frac{[Base]}{[Acid]} = 15.8$

$[Base] = 15.8 \times [Acid]$

The total of mole fraction of acid and base is 1. Therefore we have,

$[Acid] + [Base] = 1$

But Base = 15.8 x [Acid]. Let us plug in this value in above equation.

$[Acid] + 15.8 \times [Acid] = 1$

$16.8 [Acid] = 1$

$[Acid] = \frac{1}{16.8}$

$[Acid] = 0.0595$

[Acid] = 0.0595 x 100 = 5.95 %

The fraction of carbonic acid present in the blood is 5.95%

4 0

3 years ago

Read 2 more answers

What isotope is used for a standard for other atomic masses?

sergeinik [125]

Though the ratio of any two atom's masses was the same on either scale, it was horribly confusing, so in 1961, a compromise was reached. Instead of using either Hydrogen, or Oxygen as the standard, the isotope of Carbon with 6 protons and 6 neutrons in its nucleus (Carbon-12) was given a mass of exactly 12.

3 0

2 years ago

Suppose there are two known compounds containing the generic elements X and Y. You have a 1.00-g sample of each compound. One sa

Lapatulllka [165]

I think the correct answers are X2Y and X3Y, X2Y5 and X3Y5, and X4Y2 and X3Y, for the following reason:

If you look at the combining masses of X and Y in each of the two compounds,

The first compound contains 0.25g of X combined with 0.75g of Y
so the ratio (by mass) of X to Y = 1 : 3

The second compound contains 0.33 g of X combined with 0.67 g of Y
so the ratio (by mass) of X to Y = 1 : 2

Now, you suppose to prepare each of these two compounds, starting with the same fixed mass of element Y ( I will choose 12g of Y for an easy calculation!)

The first compound will then contain 4g of X and 12g of Y
The second compound will then contain 6g of X and 12g of Y

The ratio which combined the masses of X and the fixed mass (12g) of Y
= 4 : 6
or 2 : 3 

So, the ratio of MOLES of X which combined with the fixed amount of Y in the two compounds is also = 2 : 3

The two compounds given with the plausible formula must therefore contain the same ratio.

8 0

2 years ago

which is a way to express concentration of a solution? parts per billion moles molar mass force per square meter

stich3 [128]

Answer:

parts per billion

Explanation:

I took the quiz

5 0

2 years ago

Read 2 more answers