Answer:
The percentage (by mass) of KBr in the original mixture was 33.1%.
Explanation:
The mixture of KCl and KBr has a mass of 3.595g, thus the sum of the moles of KCl (<em>x</em>) multiplied by it molar mass (74.5g/mol) and the moles of KBr (<em>y</em>) multiplied by it molar mass (119g/mol) is the total mass of the mixture:
Also, after the conversion of KBr into KCl, the total mass of 3.129 g is only from KCl moles, hence
But the 0.042 moles came from the originals KCl and KBr moles, thus
Now it is possible to propose a system of equations:
Solving the system of equations,
0.010 moles of KBr multiplied it molar mass is
Therefore, the percentage (by mass) of KBr in the original mixture was:
%
Answer: elevation
, The boundaries of a watershed are determined by topography, which is the shape or the physical features of the land's surface. If the highest points of land surrounding a river were connected (like “connect-the-dots”), this line would form the watershed boundary.
Answer:
134.8 mmHg is the vapor pressure for solution
Explanation:
We must apply the colligative property of lowering vapor pressure, which formula is: P° - P' = P° . Xm
P° → Vapor pressure of pure solvent
P' → Vapor pressure of solution
Xm → Mole fraction for solute
Let's determine the moles of solute and solvent
17.5 g . 1 mol/180 g = 0.0972 moles
82 g . 1mol / 32 g = 2.56 moles
Total moles → moles of solute + moles of solvent → 2.56 + 0.0972 = 2.6572 moles
Xm → moles of solute / total moles = 0.0972 / 2.6572 = 0.0365
We replace the data in the formula
140 mmHg - P' = 140 mmHg . 0.0365
P' = - (140 mmHg . 0.0365 - 140mmHg)
P' = 134.8 mmHg
Definition of indirect evidence. : evidence that establishes immediately collateral facts from which the main fact may be inferred : circumstantial evidence.