Answer:
a. Xm = 0.0229
b. 0.0234 moles
c. 354.1 g/mol
Explanation:
ΔP = P° . Xm
ΔP = P° - P', where P° is vapor pressure of pure solvent and P', vapor pressure of solution-
This is the formula for lowering vapor pressure.
If we apply the data given: 523 Torr - 511 Torr = 523 . Xm
Xm = ( 523 Torr - 511 Torr) / 523 Torr → 0.0229
Xm = Mole fraction of solute → Moles of solute / Total moles (sv + solute)
We can make this equation to determine moles of solute
0.0229 = Moles of solute / Moles of solute + 1
0.0229 (Moles of solute + 1) = Moles of solute
0.0229 = Moles of solute - 0.0229 moles of solute
0.0229 = 0.9771 moles of solute → 0.0229 / 0.9971 = 0.0234 moles
Molecular mass of solute → g/mol → 8.3 g / 0.0234 mol = 354.1 g/mol
Answer:
B. Ca(NO2)2
Explanation:
Ions (charged atoms) combine with one another to form stable ionic compounds. In this case, calicium ion (Ca2+) is said to react with NO2, which has a charge of -1 i.e. +1-1(2) = 1-2 = -1.
This means that calcium has a charge of +2 while nitrite ion has charge of -1, hence, when they combine, they exchange their charges, which become their subscript as follows:
Ca2+ + NO2- → Ca(NO2)2
Ca(NO2)2 is a stable ionic compound called calcium nitrite. Notice that it takes two atoms of NO2- to react with one atom of Ca2+.
Answer:
The International Date Line, established in 1884, passes through the mid-Pacific Ocean and roughly follows a 180 degrees longitude north-south line on the Earth. It is located halfway round the world from the prime meridian—the zero degrees longitude established in Greenwich, England, in 1852.
The answer is 6.88.
Solution:
We can calculate for the percent composition of CaCl2 by mass by dividing the mass of the CaCl2 solute by the mass of the solution and then multiply by 100. The total mass of the resulting solution is the sum of the mass of CaCl2 solute and the mass of water solvent. Therefore, the percent composition of CaCl2 by mass is
% by mass = (mass of the solute / mass of the solution)*100
= mass of solute / (mass of the solute + mass of the solvent)*100
= (27.7 g CaCl2 / 27.7g + 375g) * 100
= 6.88
