The answer is 64.907 amu.
The atomic mass of an element is the average of the atomic masses of its isotopes. The relative abundance of isotopes must be taken into consideration, therefore:
atomic mass of copper = atomic mass of isotope 1 * abundance 1 + atomic mass of isotope 2 * abundance 2
We know:
atomic mass of copper = 63.546 amu
The atomic mass of isotope 1 is: 62.939 amu
The abundance of isotope 1 is: 69.17% = 0.6917
The atomic mass of isotope 1 is: x
The abundance of isotope 2: 100% - 69.17% = 30.83% = 0.3083
Thus:
63.546 amu = 62.939 amu * 0.6917 + x * 0.3083
63.546 <span>amu = 43.535 amu + 0.3083x
</span>⇒ 63.546 amu - 43.535 amu = 0.3083x
⇒ 20.011 amu = 0.3083x
⇒ x = 20.011 amu ÷ 0.3083 = 64.907 amu
Answer:
Fusão: a substância volta do sólido para o líquido. Condensação: a substância muda de um gás para um líquido. Vaporização: a substância muda de líquido para gás. Sublimação: a substância muda diretamente de um sólido para um gás sem passar pela fase líquida.
Answer:
98.6 g/mol.
Explanation:
Equation of the reaction
HX + NaOH--> NaX + H2O
Number of moles = molar concentration × volume
= 0.095 × 0.03
= 0.00285 moles
By stoichiometry, 1 mole of HX reacted with 1 mole of NaOH. Therefore, number of moles of HX = 0.00285 moles.
Molar mass = mass ÷ number of moles
= 0.281 ÷ 0.00285
= 98.6 g/mol.
Endothermic reactions, on the other hand, absorb heat and/or light from their surroundings. For example, decomposition reactions are usually endothermic. In endothermic reactions, the products have more enthalpy than the reactants. Thus, an endothermic reaction is said to have a positive<span> enthalpy of reaction. This means that the energy required to break the bonds in the reactants is more than the energy released when new bonds form in the products; in other words, the reaction requires energy to proceed.</span>
