<span>Percentage
by mass is the amount in mass of a component in a mixture per 100 unit of mass of the
total mixture. Percentage by mass is the same as %w/w. We can determine this by dividing the mass of the solute with the total mass of the mixture. However, from the problem statement, we are given the volume of the water so there is a need to convert this value to mass by using the density of water. We calculate as follows:
Mass of solution = 100 mL (0.99993 g/mL) water + 25 g EtOH
Mass of solution = 124.993 g solution
%w/w = 25 g / 124.993 g x100
%w/w = 20% of EtOH</span>
Explanation:
Soaps attach to both water and grease molecules.
The grease molecules are attracted more strongly towards each other as compared to water molecules. Also, water molecules are smaller in size hence, strong intermolecular force is required to break the hydrogen bonds of water molecule so that grease or oil molecules can enter the water molecule.
A soap molecule goes in between water and grease molecule and helps them to bind. The force for linkage between water and grease molecule through the soap molecule is weak london dispersion force.
The soap molecule has its salt end as ionic and water soluble. When grease or oil is added to the soap and water solution then the soap acts as an emulsifier. The soap forms miscelles of the non-polar tails and grease molecules are trapped between these miscelles. This miscelle is easily soluble in water hence, the grease is washed away.
Thus, it can be concluded that the nonpolar end of a soap molecule attaches itself to grease.
Answer:
Which wind blows cool air inland during the day? Sea Breeze
Which wind blows cool air toward the sea at night? Land Breeze
Which winds blow steadily from specific directions and over long distances? Global Winds
Thermal energy will flow from an object high temperature to an object of low one. In this case, the thermal energy will flow from object B to object A.
The answer is 2.135 mol/Kg
Given that molarity is 2M, that is, 2 moles in 1 liter of solution.
Density of solution is 1.127 g/ml
Volume of solution is 1L or 1000 ml
mass of solution (m) = density × volume
m₁ = density × volume = 1.127 × 1000 = 1127 g
mass of solute, m₂ = number of moles × molar mass
m₂ = 2 × 95.211
m₂ = 190.422 g
mass of solvent = m₁ - m₂
= 1127 - 190.422
= 936.578 g
= 0.9366 Kg
molality = number of moles of solute / mass of solvent (in kg)
= 2 / 0.9366
= 2.135 mol/Kg
