Will ice melt faster with a lot of salt added or little salt added?

The colligative molality of an unknown aqueous solution is 1.56 m.

yawa3891 [41]

Answer:

Vapor pressure of solution = 17.02 Torr

T° of boiling point for the solution is 100.79°C

T° of freezing point for the solution is -2.9°C

Explanation:

Let's state the colligative properties with their formulas

- Vapor pressure lowering

ΔP = P° . Xm . i

- Boiling point elevation

ΔT = Kb . m . i

- Freezing point depressión

ΔT = Kf . m . i

ΔP = Vapor pressure pure solvent (P°) - Vapor pressure solution

ΔT = T° boling solution - T° boiling pure solvent

ΔT = T° freezing pure solvent - T° freezing solution

i represents the Van't Hoff factor (ions dissolved in the solution). If we assume that the solute is non-volatile and the solution is ideal i = 1

Kf and Kb are cryoscopic and ebulloscopic constant, they are specific to each solvent.

Vapor pressure works with mole fraction (Xm) and the only data we have is molality, so we consider 1.56 moles of solute and 1000 g of solvent mass.

Moles of solvent → solvent mass / molar mass of solvent

Moles of solvent → 1000 g / 18 g/mol = 55.5 moles

Mole fraction is moles of solute / Total moles (mol st + mol sv)

Mole fraction: 1.56 / (1.56 + 55.5) = 0.027

- Vapor pressure lowering

ΔP = P° . Xm . i

17.5 Torr - Vapor pressure of solution = 17.5 Torr . 0.027 . 1

Vapor pressure of solution = - (17.5 Torr . 0.027 . 1 - 17.5 Torr)

Vapor pressure of solution = 17.02 Torr

- Boiling point elevation

ΔT = Kb . m . i

T° boiling solution - 100° = 0.512 °C/ m . 1.56 m . 1

T°boiling solution = 0.512 °C/ m . 1.56 m . 1 + 100°C

T°boiling solution = 100.79°C

- Freezing point depression

ΔT = Kf . m . i

0°C - T° freezing solution = 1.86 °C/m . 1.56 m . 1

T° freezing solution = - (1.86 °C/m . 1.56 m)

T° freezing solution = -2.9°C

3 0

3 years ago

Be sure to answer all parts. In winemaking, the sugars in grapes undergo fermentation by yeast to yield CH3CH2OH (ethanol) and C

Ede4ka [16]

Answer:

a)- Fermentation = - 2 816 kJ/mol

Respiration = - 1409.2 kJ/mol

b)C₂H₅OH (l) + 3O₂ (g) → 3H₂O(g) + 2CO₂(g)

c) combustion per mol of sugar

Explanation:

a)

The fermentation of sugar is given as follows:

C₆H₁₂O₆ (s) + 6O₂ (g) → 6O₂ (g) + 6H₂O (l)

ΔHrxn = ΔHformation (products) - ΔHformation (reactants)

= (6 mol × -393.5kJ/mol)+ (6mol × -285.8kJ/mol) - (1 mol × -1260kJ/mol + 6mol × 0)

= -2 816 kJ/mol

The heat of combustion of ethanol is given as follows:

C₂H₅OH (l) + 3O₂ (g) → 3H₂O(g) + 2CO₂(g)

Let's assume that 1 mol of ethanol is burnt. The heat of reaction, ΔHrxn is given by this equation:

ΔHrxn = ΔHformation (products) - ΔHformation (reactants)

= (2 mol× - 393.5kJ/mol) + ( 3mol × -285.8kJ/mol) - [ (1mol × -235 kJ/mol) + ( 3mol × 0.0000kJ)]

= -1644 - (-235.2)

= - 1409.2 kJ/mol

Therefore, the combustion of ethanol is exothermic. In other words, heat iis given off (this is signified by the negative sign)

b) Ethanol, like any other fuel, burns up to give water and carbon dioxide. This is based on the assumption that the combustion is complete and no side reactions take place. The combustion of ethanol is given as follows:

C₂H₅OH (l) + 3O₂ (g) → 3H₂O(g) + 2CO₂(g)

The physical states are given in the parentheses.

c) From the comparisons of the ΔHrxn, sugar produces more energy.

4 0

3 years ago

The center of the earth is very hot

Arturiano [62]

true. is this what you were looking for?

8 0

3 years ago

Fat,minerals,vitamins,water which is odd one

jolli1 [7]

The one that starts with c that is also the one that is anwser number c which is a

7 0

2 years ago

with respect to composition, how is the compound made from hydrogen and oxygen different from mixtures of these two elements?

erastovalidia [21]

Each substance in the mixture keeps its own properties and can be easily separated from the mixture. In a mixture of hydrogen and oxygen, molecules of both the gases will exist independently.
The compound on the other hand has properties different from the elements it contains. In water as a compound of hydrogen and oxygen what you will have is molecules of H20.

8 0

3 years ago