Answer:
A. endothermic.
A. Yes, absorbed.
Explanation:
Let's consider the following thermochemical equation.
2 HgO(s) ⇒ 2 Hg(l) + O₂(g) ΔH = 182 kJ
The enthalpy of the reaction is positive (ΔH > 0), which means that the reaction is endothermic.
182 kJ are absorbed when 2 moles of HgO react (molar mass 216.59 g/mol). The heat absorbed when 72.8 g of HgO react is:
![72.8g.\frac{1mol}{216.59g} .\frac{182kJ}{2mol} =30.6kJ/mol](https://tex.z-dn.net/?f=72.8g.%5Cfrac%7B1mol%7D%7B216.59g%7D%20.%5Cfrac%7B182kJ%7D%7B2mol%7D%20%3D30.6kJ%2Fmol)
Explanation:
Relation between pH and concentration of hydrogen ions is as follows.
pH = ![-log [H^{+}]](https://tex.z-dn.net/?f=-log%20%5BH%5E%7B%2B%7D%5D)
So, it means that an increase in the value of pH will show that there occurs a decrease in concentration of hydrogen ions.
Therefore, the solution becomes basic in nature.
On the other hand, a decrease in the value of pH will show that there occurs an increase in the concentration of hydrogen ions.
Therefore, the solution becomes more acidic in nature.
Hence, if the pH of a solution is decreased from pH 8 to pH 6 it means that the concentration of hydrogen ions has increased in the solution.
<span>B.by arranging the elements according to atomic number instead of atomic mass</span> awnser is B
Answer:
Enthalpy of formation = -947.68KJ/mol
Explanation:
Enthalpy of formation is the heat change when one mole of a substance is formed from its element in its standard states and in standard conditions of temperature and pressure. it may be positive or negative, if positive, it is an endothermic reaction where the heat content of the product is greater than that of the reactants, and if negative, it is exothermic reaction - where the heat content of the reactants is greater than the products. the enthalpy of formation is measured in KiloJoule/Moles (KJ/Mole).
From the value of the enthalpy of formation of NaHCO3, it shows that the reaction is exothermic, that is the formation of NaHCO3 from its constituents elements. As such, the heat content of the reactants is greater than the products.
The step by step explanation is shown in the attachment.
This is not chemistry but it's A, off top.