An atom's Lewis dot structure has four dots. Which of the following elements could it be, and why?

When 0.5141 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 25.823 °C to 29.419 °C

natka813 [3]

Answer:

$\Delta_{r}U$ of the reaction is -6313 kJ/mol

$\Delta_{r}H$ of the reaction is -6312 kJ/mol

Explanation:

$Temperature\,\,change= \Delta U = 29.419-25.823 =3.506^{o}C$

$q_{cal}= C \times \Delta T$

$=5.861 \times 3.596 = 21.076\,kJ$

$q_{rxn}= -q_{cal}= -21.076\,kJ$

$\Delta_{r}U= -21.076 \times \frac{154}{0.5141}= -6313\, kJ/mol$

Therefore, $\Delta_{r}U$ of the reaction is -6313 kJ/mol.

The chemical reaction in bomb calorimeter is as follows.

$C_{12}H_{10}(s)+\frac{27}{2}O_{2}(g)\rightarrow 12CO_{2}(g)+5H_{2}O(g)$

$Number\,of\,moles\Delta n=(12+5)-\frac{27}{2}=3.5$

$\Delta_{r}H=\Delta E+ \Delta n. RT$

$=-6313+3.5\times 8.314\times 10^{-3} \times 3.596=-6312\,kJ/mol$

Therefore, $\Delta_{r}H$ of the reaction is -6312 kJ/mol.

3 0

3 years ago

The heating curve for a sample of pure ethanol shows the slope of the line for gaseous state is greater than the slope of the li

Agata [3.3K]

Answer:

a. The specific heat capacity of the gaseous ethanol is less than the specific heat capacity of liquid ethanol.

Explanation:

The heating curve is a curve that represents temperature (T) in the y-axis vs. added heat (Q) in the x-axis. The slope is T/Q = 1/C, where C is the heat capacity. Then, the higher the slope, the lower the heat capacity. For a constant mass, it can also represent the specific heat capacity (c).

Heats of vaporization and fusion cannot be calculated from these sections of the heating curve.

<em>Which statement below explains that?</em>

<em>a. The specific heat capacity of the gaseous ethanol is less than the specific heat capacity of liquid ethanol.</em> YES.

<em>b. The specific heat capacity of the gaseous ethanol is greater than the specific heat capacity of liquid ethanol.</em> NO.

<em>c. The heat of vaporization of ethanol is less than the heat of fusion of ethanol.</em> NO.

<em>d. The heat of vaporization of ethanol is greater than the heat of fusion of ethanol.</em> NO.

3 0

3 years ago

How many moles are in 2.98x10^23 particles?

Novosadov [1.4K]

Answer:

$\boxed {\boxed {\sf 0.495 \ mol}}$

Explanation:

We are given a number of particles and asked to convert to moles.

<h3>1. Convert Particles to Moles </h3>

1 mole of any substance contains the same number of particles (atoms, molecules, formula units) : 6.022 *10²³ or Avogadro's Number. For this question, the particles are not specified.

So, we know that 1 mole of this substance contains 6.022 *10²³ particles. Let's set up a ratio.

$\frac { 1 \ mol }{6.022*10^{23 } \ particles}}$