Answer: (a) There are 0.428 moles present in 12 g of 
molecule.
(b) There are 2 moles present in 
particles of oxygen.
Explanation:
(a). The mass of nitrogen molecule is given as 12 g.
As the molar mass of is 28 g/mol so its number of moles are calculated as follows.
So, there are 0.428 moles present in 12 g of molecule.
(b). According to the mole concept, 1 mole of every substance contains 
atoms.
Therefore, moles present in particles are calculated as follows.
So, there are 2 moles present in particles of oxygen.
Answer:
false. acids do not neutralize bases.
Explanation:
Enthalpy of formation is calculated by subtracting the total enthalpy of formation of the reactants from those of the products. This is called the HESS' LAW.
ΔHrxn = ΔH(products) - ΔH(reactants)
Since the enthalpies are not listed in this item, from reliable sources, the obtained enthalpies of formation are written below.
ΔH(C2H5OH) = -276 kJ/mol
ΔH(O2) = 0 (because O2 is a pure substance)
ΔH(CO2) = -393.5 kJ/mol
ΔH(H2O) = -285.5 kJ/mol
Using the equation above,
ΔHrxn = (2)(-393.5 kJ/mol) + (3)(-285.5 kJ/mol) - (-276 kJ/mol)
ΔHrxn = -1367.5 kJ/mol
<em>Answer: -1367.5 kJ/mol</em>
Answer:
111.15 g are required to prepare 500 ml of a 3 M solution
Explanation:
In a 3 M solution of Ca(OH)₂ there are 3 moles of Ca(OH)₂ per liter solution. In 500 ml of this solution, there will be (3 mol/2) 1.5 mol Ca(OH)₂.
Since 1 mol of Ca(OH)₂ has a mass of 74.1 g, 1.5 mol will have a mass of
(1.5 mol Ca(OH)₂ *(74.1 g / 1 mol)) 111.15 g. This mass of Ca(OH)₂ is required to prepare the 500 ml 3 M solution.
Answer:
They are due to past earthquakes
