What did Aristotle believe?

171 g of sucrose ( MW of 342, melting point 186 oC, boiling point very high, and vapor pressure is negligible) is dissolved in o

Fantom [35]

The complete question is as follows: 171 g of sucrose ( MW of 342, melting point 186 oC, boiling point very high, and vapor pressure is negligible) is dissolved in one liter of water at 25 oC. At 25 oC the vapor pressure of water is 24 mmHg. Which value is closest to the vapor pressure (VP) of this solution at 25 oC?

a. 16mm Hg

b. 24mm Hg

c. 20mm Hg

d. 12mm Hg

Answer: The vapor pressure (VP) of this solution at $25^{o}C$ is closest to the value 24 mm Hg.

Explanation:

Given: Mass of sucrose = 171 g

Mass of water = 1 L = 1000 g

Vapor pressure of water = 24 mm Hg

As moles is the mass of substance divided by its molar mass. Hence, moles of water (molar mass = 18.02 g) is calculated as follows.

$Moles = \frac{mass}{molar mass}\\= \frac{1000 g}{18.02 g/mol}\\= 55.49 mol$

Similarly, moles of sucrose (molar mass = 342 g/mol) is as follows.

$Moles = \frac{mass}{molar mass}\\= \frac{171 g}{342 g/mol}\\= 0.5 mol$

Total moles = 55.49 + 0.5 mol = 55.99 mol

Mole fraction of water is as follows.

$Mole fraction = \frac{moles of water}{total moles}\\= \frac{55.49}{55.99}\\= 0.99$

Formula used to calculate vapor pressure of the solution is as follows.

$P_{i} = P^{o}_{i} \times \chi_{i}$

where,

$P_{i}$ = vapor pressure of component i over the solution

$P^{o}_{i}$ = vapor pressure of pure component i

$\chi_{i}$ = mole fraction of i

Substitute the values into above formula to calculate vapor pressure of water as follows.

$P_{i} = P^{o}_{i} \times \chi_{i}\\= 24 mm Hg \times 0.99\\= 23.76 \\or 24 mm Hg\\$

Thus, we can conclude that the vapor pressure (VP) of this solution at $25^{o}C$ is closest to the value 24 mm Hg.

4 0

3 years ago

The periodic table of the elements lists the elements in order of increasing atomic number. Each element has its own unique squa

Vesna [10]

Answer:

A) They all have 12 protons.

Explanation:

Magnesium has an atomic number of 12 which means it has 12 protons. All Magnesium atoms have 12 protons, the neutrons however may differ which produces things called isotopes where the atoms have same protons but neutrons change.

Keep in mind the atomic number is unique to each element, so 12 atomic number will always be Magnesium, 1 will always be Hydrogen and so on.....

6 0

3 years ago

Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the equation: CO2(s)→CO2(g). Whe

MA_775_DIABLO [31]

Answer:

6.82 kg

Explanation:

Given that the amount of water is 15L and we know that the density of water is ≈ 1kg/L. The mass of water is given by mass = volume x density, i.e,

mass = 15 x 1 = 15 kg. Also the specific heat capacity of water is 4.186 KJ/kg.

The sublimation enthalpy of dry ice is 571 KJ/kg.

Now, the amount of heat lost by water is entirely used up for the sublimation (conversion from soild to gas) of dry ice. And the heat (Q) lost by water is given as : Q = mCΔT, where m is the mass of water, C the specific heat capacity of water and ΔT the change in temperature.

Here, Q = 15 x 4.186 x (90 - 28) = 3892.98 KJ.

This amount of heat is taken up by the dry ice for its sublimation. Also the energy taken by dry ice (Q') for its sublimation is given by: Q' = m'L', where m' is the mass of dry ice, L' is the latent heat of sublimation (i.e, the amount of heat required per kg of a substance to sublime) of dry ice amd L' = 571 KJ/kg.

Now, Q' =m'L' = heat lost by water = 3892.98KJ.

And, m'L' = m' x 571 KJ/kg = 3892.98 KJ. (Dividing with 571)

Therefore, m' = 6.82 kg.

6 0

3 years ago

The equilibrium constant, Kc, is calculated using molar concentrations. For gaseous reactions another form of the equilibrium co

Anarel [89]

Answer:

Kp = 1.41 x 10⁻⁶

Explanation:

We have the chemical equation:

2 A(g) + 3 B(g)⇌ C(g)

In which A and B are the reactants and C is the product. We calculate first the change in the number of moles of gas (Δn or dn):

dn= (sum moles products - sum moles reactants)

= (moles C - (moles A + moles B))

= (1 - (2+3))

= 1 - 5

= -4

We have also the following data:

Kc = 63.2

T= 81∘C + 273 = 354 K

R = 0.082 L.atm/K.mol (it is a constant)

Thus, we introduce the data in the mathematical expression for the relation between Kp and Kc:

$Kc = (RT)^{dn}$ = (0.082 L.atm/K.mol x 354 K)⁻⁴ = 1.41 x 10⁻⁶

3 0

3 years ago

What is the [OH-] in a solution if the [H*] = 1.2 x 10-3 M?

spayn [35]

We know that [OH⁻] * [H⁺] = 10⁻¹⁴

plugging the value of [H⁺]

[OH⁻] * 1.2 * 10⁻³ = 10⁻¹⁴

[OH⁻] = 10⁻¹⁴ * (10³/1.2)

[OH⁻] = 833.3 * 10⁻¹⁴

[OH⁻] = 8.33 * 10⁻¹²

7 0

3 years ago