Answer:
42.1 kj
Explanation:
Given data:
Molar heat of vaporization = 3.86×10⁴ j/mol
Mass of ethanol = 50 g
Amount of heat required to convert into gaseous form = ?
Solution:
First of all we will calculate the number of moles of ethanol.
Number of moles = mass/ molar mass
Number of moles = 50.0 g/ 46.07 g/mol
Number of moles = 1.09 mol
H(vap) = number of moles × molar heat of vaporization
H(vap) = 1.09 mol × 3.86×10⁴ j/mol
H(vap) = 4.21×10⁴ j
In Kj:
4.21×10⁴ / 1000 = 42.1 kj
Evidence could be gathered in the future that contradicts original theories. <span>Phenomena cannot be proven by conclusive evidence in science because, as of now, the evidence isn't conclusive. It is speculation. Just as a phenomena cannot be proven, it also cannot be disproven. </span>
Answer:
D. I < III < II
Explanation:
- The osmotic pressure (π) is given by the relation:
<em>π = iMRT.</em>
where, π is the osmotic pressure.
i is van 't Hoff factor.
M is the molarity of the solution.
R is the general gas constant.
T is the temperature.
<em>M, R and T are constant for all solutions.</em>
So, the osmotic pressure depends on the van 't Hoff factor.
- The van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.
- For most non-electrolytes dissolved in water, the van 't Hoff factor is essentially 1.
- For most ionic compounds dissolved in water, the van 't Hoff factor is equal to the number of discrete ions in a formula unit of the substance.
For C₂H₆O₂ (non-electrolyte solute): i = 1.
For MgCl₂: i = 3.
It dissociates to give (Mg²⁺ + 2Cl⁻).
For NaCl: i = 2.
It dissociates to give (Na⁺ + Cl⁻).
So, the solute that has the highest osmotic pressure is II. 0.15 M MgCl₂, then III. 0.15 M NaCl, then I. 0.15 M C₂H₆O₂.
<em>D. I < III < II.</em>
<em></em>
Answer:- The charge is +2.
Explanations:- Z stands for atomic number. The Z is given as 25 means the atomic number of the element is 25. It has 23 electrons. For a neutral atom the number of electrons is same as the atomic number. Since the number of electrons is less than atomic number, the atom must have lost the electrons.
Number of electrons lost = 25 - 23 = 2
If the element lost electrons then it has positive charge. As, the electrons are lost, the charge is +2.
