Answer:
Substances can change phase—often because of a temperature change. At low temperatures, most substances are solid; as the temperature increases, they become liquid; at higher temperatures still, they become gaseous.
The process of a solid becoming a liquid is called melting. (an older term that you may see sometimes is fusion). The opposite process, a liquid becoming a solid, is called solidification. For any pure substance, the temperature at which melting occurs—known as the melting point—is a characteristic of that substance. It requires energy for a solid to melt into a liquid. Every pure substance has a certain amount of energy it needs to change from a solid to a liquid. This amount is called the enthalpy of fusion (or heat of fusion) of the substance, represented as ΔHfus. Some ΔHfus values are listed in Table 10.2 “Enthalpies of Fusion for Various Substances”; it is assumed that these values are for the melting point of the substance. Note that the unit of ΔHfus is kilojoules per mole, so we need to know the quantity of material to know how much energy is involved. The ΔHfus is always tabulated as a positive number. However, it can be used for both the melting and the solidification processes as long as you keep in mind that melting is always endothermic (so ΔH will be positive), while solidification is always exothermic (so ΔH will be negative).
Table 10.2 Enthalpies of Fusion for Various Substances
Explanation:
La primera instrucción es verdadera, la segunda es falsa porque dos elementos no pueden tener el mismo número de masa (excepto azufre y argón) Estrictamente hablando, No. Puede tener 2 (o más) elementos con el mismo 'número de masa atómica', lo que significa que el número total de nucleones (neutrones de protones) es el mismo. En el ejemplo dado en una respuesta anterior, el azufre tiene un isótopo con el número de masa atómica 36 (16p 20n) y Argón también tiene un 36 (18p 18n). La tercera declaración es verdadera, si tiene un número diferente de neutrones, entonces es un isótopo. La cuarta declaración es falso. Espero que esto te ayude.
Answer:
a) The molecular mass of each compound dinitrogen pentaoxide is 108 g/mol.
b) The molecular mass of each compound lead(ll) nitrat is 331 g/mol.
c) The molecular mass of each compound calcium peroxide is 72 g/mol.
Explanation:
a) Molecular mass of dinitrogen pentaoxide that be M.
Mass of nitrogen atom = 14 g/mol
Mass of oxygen atom = 16 g/mol
b) Molecular mass of lead(ll) nitrate that be M.
Mass of lead = 207 g/mol
Mass of nitrogen atom = 14 g/mol
Mass of oxygen atom = 16 g/mol
c)Molecular mass of calcium peroxide that be M.
Mass of calcium atom = 40 g/mol
Mass of oxygen atom = 16 g/mol
Answer:
lies far beyond pluto and the most distant edges of kuiper belt
Answer:
The answer is
<h2>1.74 g/mL</h2>
Explanation:
The density of a substance can be found by using the formula
From the question
mass of magnesium = 11.81 g
volume = 6.80 mL
The density of the metal is
We have the final answer as
<h3>1.74 g/mL</h3>
Hope this helps you