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4 years ago

how does the energy required to sublime a substance compare to the energy required to melt the substance

1 answer:

3 0

The energy required to sublime (solid to gas) a substance at 1 ATM pressure is greater than the energy required to melt (solid to liquid) a substance. When you compare the energies in varying pressures, however, this trend is not always the case.

any 'general phase diagram', you can see that under the triple point, when all phases are in equilibrium, have solid and gas meeting under a certain pressure. In a vacuum, it would require less energy to sublime than to melt.

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Calculate ΔHo for the following reaction ussing the given bond dissociation energiesCH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)BOND

Mazyrski [523]

Answer:

The ΔH° for the following reaction is -794 kJ, hence exothermic reaction,

Explanation:

$CH_4(g) + 2O_2(g)\rightarrow CO_2(g) + 2H_2O(g) ,$ ΔH° = ?

We are given with:

$\Delta H_{O-O}=142 kJ/mol$

$\Delta H_{O=O}=498 kJ/mol$

$\Delta H_{H-O}=459 kJ/mol$

$\Delta H_{C-H}=411 kJ/mol$

$\Delta H_{C-O}=358 kJ/mol$

$\Delta H_{C=O}=799 kJ/mol$

ΔH° =

(Energies required to break bonds on reactant side) - (Energies released on formation of bonds on product side)

$\Delta H^o=(1 mol\times 4\times \Delta H_{C-H}+2 mol\times 1\times \Delta H_{O=O})-(1 mol\times 2\times \Delta H_{C=O}+2 mol\times 2\times\Delta H_{H-O})$

$\Delta H^o=(1 mol\times 4\times 411 kJ/mol+2 mol\times 1\times 498 kJ/mol)-(1 mol\times 2\times 799 kJ/mol+2 mol\times 2\times 459 kJ/mol)$

$\Delta H^o=-794kJ$

$\Delta H^o>0$ endothermic reaction

$\Delta H^o$ exothermic reaction

The ΔH° for the following reaction is -794 kJ, hence exothermic reaction,

4 0

4 years ago

What is the correct formula for sodium carbonate?

frosja888 [35]

Answer:

na2 co3

Explanation:

sodium carbonate formula

4 0

4 years ago

Read 2 more answers

Select the correct answer. How does an atom become a positively charged ion? A. By gaining one or more electrons B. By gaining o

ser-zykov [4K]

C. By losing one or more electrons

6 0

3 years ago

Read 2 more answers

Which statement is true for an open system?

Bingel [31]

Answer:

Before we get into the first law of thermodynamics we need to understand the relation between heat and work and the concept of internal energy. Just like mass, energy is always conserved i.e. it can neither be created nor destroyed but it can be transformed from one form to another. Internal energy is a thermodynamic property of the system that refers to the energy associated with the molecules of the system which includes kinetic energy and potential energy.

Whenever a system goes through any change due to interaction of heat, work and internal energy, it is followed by numerous energy transfer and conversions. However, during these transfers, there is no net change in the total energy.

Similarly, if we look at the first law of thermodynamics it affirms that heat is a form of energy. What it means is that the thermodynamic processes are governed by the principle of conservation of energy. The first law of thermodynamics is also sometimes referred to as the Law of Conservation of Energy

Explanation:

3 0

3 years ago

Which is not a functional group A. Carboxyl B. Halide C. Hydroxyl D. Protein

xeze [42]

I believe it’s B. Halide

7 0

3 years ago