Balance them i dont get how

Butane (C4H10) has a heat of vaporization of 22.44 kJ/mol and a normal boiling point of -0.4 ∘C. A 250 mL sealed flask contains

erastova [34]

Given that:

The heat of vaporization = 22.44 kJ/mol = 22440 J/mol
normal boiling point which is the initial temperature = 0.4° C = (273 + (-0.4))K = 272.6 K
volume = 250 mL = 0.250 L
Mass of butane = 0.8 g
the final temperature = -22° C = (273 + (-22)) K = 251 K

The first step is to determine the vapor pressure at the final temperature of 251K by using the Clausius-Clapeyron equation. This is following by using the ideal gas equation to determine the numbers of moles of butane gas. After that, the mass of butane present in the liquid is determined by using the relation for the number of moles.

Using Clausius-Clapeyron Equation:

$\mathbf{In (\dfrac{P_2}{P_1} )= -\dfrac{\Delta H_{vap}}{R}(\dfrac{1}{T_2} - \dfrac{1}{T_1})}$

where;

P1 and P2 correspond to the temperature at T1 and T2.

∴

replacing the values into the given equation, we have;

$\mathbf{In \dfrac{P_2}{1\ atm} = -\dfrac{22440 \ J/mol}{8.314 \ J/mol.K}(\dfrac{1}{251 \ K} - \dfrac{1}{272.6 \ K})}$

$\mathbf{In \dfrac{P_2}{1\ atm} =-(0.852053785)}$

$\mathbf{P_2=0.427 \ atm}$

As such, at -22° C; the vapor pressure = 0.427 atm

Now, using the ideal gas equation:

PV = nRT

where:

P = Pressure
V = volume
n = number of moles of butane
R = universal gas constant
T = temperature

∴

Making (n) the subject of the formula:

$\mathbf{n = \dfrac{PV}{RT}}$

$\mathbf{n = \dfrac{0.427 atm \times 0.250 L}{(0.08206 \ L.atm/k.mol) \times 251}}$

$\mathbf{n =0.00518 mol}$

We all know that the standard molecular weight of butane = 58.12 g/mol

∴

Using the relation for the number of moles which is:

$\mathbf{number \ of \ moles = \dfrac{mass}{molar mass}}$

mass = 0.00518 mole × 58.12 g/mol

mass = 0.301 g

∴

The mass of butane in the flask = 0.301 g

But the mass of the butane present as a liquid in the flask is

= 0.8 g - 0.301 g

= 0.499 g

In conclusion, the mass of the butane present as a liquid in the flask is 0.499 g

Learn more about vapourization here:

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7 0

3 years ago

Determine the number of grams of magnesium oxide if you have 2.63 moles of magnesium oxide.

ANTONII [103]

The number of grams of Magnesium oxide= 106 g

<h3>Further explanation</h3>

Given

2.63 moles of Magnesium oxide

Required

mass of Magnesium oxide

Solution

The mole is the number of particles contained in a substance

Moles can also be determined from the amount of substance mass and its molar mass

Mol = mass : Molar mass

Mass of Magnesium oxide(MgO, MW=40.304 g/mol) :

= mol x MW

= 2.63 x 40.304

= 106 g

3 0

3 years ago

The two largest metropolitan areas in Canada are Toronto and

vaieri [72.5K]

The answers is a. Montreal, with a population of 1.65 million.

8 0

3 years ago

The scientific method is "flexible". What does that mean? Why is that<br> important and necessary?

WITCHER [35]

Answer:

we can reach the same conclusions by applying different experimental and observational procedures

Explanation:

The scientific method is a process that can be summarized in the following steps: 1-to raise a question, 2-to make a hypothesis, 3-to obtain data from observations and/or experiments, and finally, 4-to obtain conclusions that enable to confirm (or reject) the hypothesis. The scientific method is flexible because it is not necessary to follow 'stringent' guidelines in order to reach the same conclusions. In consequence, the predictions derived from such results can be tested again to determine the veracity of the results.

3 0

3 years ago

the ionization energies of several of the Group 1 elements in the periodic table are shown in the table below

Vikentia [17]

In a group,the ionization energy decreases because the atomic size increases(no. of shells increases, therefore due to this, there's a weak attractive force between nucleus and the valence electrons)

3 0

3 years ago