Answer:
0.018 moles of isooctane must be burned to produce 100 kJ.
Explanation:
When the isooctane is <em>burned</em>, it undergoes a reaction known as combustion, in which reacts with oxygen to produce carbon dioxide and water. In standard conditions (Pressure = 1 atm and Temperature = 298 K) formed water is liquid. The balanced equation is:
C₈H₁₈(l) + 12.5 O₂(g) ⇄ 8 CO₂(g) + 9 H₂O(l)
The standard enthalpy of combustion (which can be found in tables) relates the amount of isooctane that reacts and the heat the reaction liberates. In this case, ΔH°c = -5,460 kJ/mol, that is every 1 mol of isooctane that burns, 5,460 kJ of heat are released.
We can begin with the information of 100 kJ and apply this conversion factor. Since this energy is released, by convention, we write it with a minus sign.
Answer:
1 mole of calcium contains 6.023
atoms.
Explanation:
1 mole is the amount of a substance that contains exactly
constituent particles. 1 mole of a substance is always equal to the atomic mass of the element.
Hence, 1 mole of calcium will also have
atoms.
Number of atoms in 1 mole calcium = 6.023
atom
2.48 g/mL
Density = mass/volume = (205 g)/(82.5 mL) = 2.48 g/mL