Answer:
<em>When salt is dissolved in water</em>, many physical properties change, among them the so called colligative properties:
- The vapor pressure of water decreases,
- The boiling point increases,
- The freezing point decreases, and
- Osmotic pressure appears.
Explanation:
Colligative properties are the physical properties of the solvents whose change is determined by the number of particles (moles or ions) of the solute added.
The colligative properties are: vapor pressure, boiling point, freezing point, and osmotic pressure.
<u>Vapor pressure</u>:
The vapor pressure is the pressure exerted by the vapor of a lquid over its surface, in a closed vessel.
The vapor pressure increases when a solute is added, because the presence of the solute causes less solvent molecules to be near the surface ready to escape to the vapor phase, which means that the vapor pressure is lower.
<u>Boiling point</u>:
The boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. Since we have seen that the vapor pressure of water decreases when a solute occupies part of the surface, now more temperature will be required for the water molecules reach the atmospheric pressure. So, the boiling point increases when salt is dissolved in water.
<u>Freezing point</u>:
The freezing point is the temperarute at which the vapor pressure of the liquid and the solid are equal. Since, the vapor pressure of water with salt is lower than that of the pure water, the vapor pressure of the liquid and solid with salt will be equal at a lower temperature. Hence, the freezing point is lower (decreases).
<u>Osmotic pressure</u>:
Osmotic pressure is the additional pressure that must be exerted over a solution to make that the vapor pressure of the solvent in the solution equals the vapor pressure of the pure solvent. This additional pressure is proportional to the concentration of the solute: the higher the salt concentration the higher the osmotic pressure.
I would say that honestly reporting experimental findings is an example of using good science because science is definitely about honesty in accepting experimental findings and realizing that one has to face up to the consequences and develop things from there rather than wishing the outcome was different.
<span>Propane is C3H8
The balanced equation is:
C3H8 + 5 O2 --> 3 CO2 + 4 H2O
From the balanced equation you can see that for each mole of C3H8 you obtain 4 moles of H2O.
moles H2O = 5.0 moles C3H8(4 moles H2O/1 mole C3H8) = 20 moles H2O formed
Use Avogadro's number to find the number of molecules.
molecules H2O = 20 moles H2O(6.02 x 10^23 molecules/1 mole) = 1.20 x 10^25 H2O molecules</span><span>
</span>
