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3 years ago

Calculate molality of a 2m aq solution of sodium chloride with density 1.35g/mol

1 answer:

swat323 years ago

5 0

There are a number of ways to express concentration of a solution. This includes molarity and molality. Molarity is expressed as the number of moles of solute per volume of the solution while molality is expressed as the number of moles solute per mass of solution. Calculation is as follows:

(2 mol NaCl / L solution) ( 1 cm^3 / 1.35 g) ( 1000 L / 1 cm^3) (1000 g /kg) = 1.5 x 10^6 mol / kg solution

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Lons can have a positive or negative charge.<br> True or false

fiasKO [112]

Yes, it is true that ions can have a positive or negative charge.

7 0

3 years ago

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it takes 463 kJ/mol to break an oxygen-hydrogen single bond. calculate the maximum wavelength of light for which an oxygen-hydro

Marianna [84]

Answer:

<u>2.59 × 10⁻⁷ m = 259 nm</u>

Explanation:

You need to calculate the wavelength of a photon with an energy equal to 463 kJ/mol, which is the energy to break an oxygen-hydrogen atom.

The energy of a photon and its wavelength are related by the Planck - Einstein equation:

E = hν,

Where:

E = energy of a photon,

h = Planck constant (6.626 × 10⁻³⁴ J . s) and

ν = frequency of the photon.

And:

ν = c / λ

Where:

c = speed of light (3.00 × 10⁸ m/s in vacuum)

λ = wavelength of the photon

Thus, you can derive:

E = h c / λ

Solve for λ:

λ = h c / E

Before substituting the values, convert the energy, 463 kJ/ mol, to J/bond

463 kJ/ mol × 1,000 J/kJ × 1 mol / 6.022 × 10 ²³ atom × 1 bond / atom

= 7.69×10²³ J / bond

Substitute the values and use the energy of one bond:

λ = 6.626 × 10⁻³⁴ J . s × 3.00 × 10⁸ m/s / 7.69×10²³ J = 2.59 × 10⁻⁷ m

The wavelength of light is usually shown in nanometers:

2.59 × 10⁻⁷ m × 10⁹ nm / m = 259 nm ← answer

6 0

3 years ago

hen adding a solute to water, the vapor pressure will __________ and the boiling point will __________.

Nina [5.8K]

Answer:

decrease, increase

Explanation:

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2 years ago

Atmospheric pressure at the summit of mount everest is about one third the pressure at sea level, which is 760 mm hg. if oxygen

vichka [17]

Atmospheric pressure at sea level is 760 mmHg.
We have been told that at the summit the pressure is only one third the pressure at sea level.
Then the pressure at the mountain top is $\frac{760}{3}$ mmHg
Air is made of a mixture of gases. the pressure that each gas exerts individually contributes to the total pressure of the system. The pressure that each gas exerts is the partial pressure of that gas which depends on the mole fraction of that gas or percentage composition of the individual gas.
Partial pressure of Oxygen - total pressure x percentage composition
Therefore pO₂ - $\frac{760 * 0.21}{3}$ = 53.2 mmHg
Answer is 53 mmHg

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3 years ago

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Given the following: I) N20(g) 1/2 02(g) 2 NO(g) II) N2(g) 02(g) 2 NO(g) Ke= 4.1 x 10-31 Ke= 1.7 x 10-13 Find the value of the e

tresset_1 [31]

Answer:

Answer B) 4.2x10^17

Explanation:

To produce the reaction 3 using reaction 1 and 2 we need to invert the order of the first reaction the second in the same order, as it's shown:

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